Parasites: A Treatise on the Entozoa of Man and Animals
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Title: Parasites: A Treatise on the Entozoa of Man and Animals
Author: T. Spencer Cobbold
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Transcriber’s notes:
The text contains numerous inconsistencies involving spelling,
hyphenation, punctuation, and other aspects. Some of the spelling
variations possibly represent authentic contemporary alternatives while
others may be attributable to the variety of languages occurring in the
book – English, Italian, German, Spanish, Danish, Swedish, Dutch, French,
Portuguese and possibly others.
Spelling inconsistencies that are clearly typos have been corrected
where appropriate but those representing alternative spellings have been
left unchanged. A list of corrections and common inconsistencies is
appended at the end of the book.
Punctuation anomalies have been corrected silently (e.g. missing
periods, commas and semicolons, incorrect or missing quotation marks,
unpaired parentheses), particularly in the extensive bibliographic
lists, in the index and in the Figure captions.
There is significant inconsistency between the headings displayed in the
Table of Contents (TOC) and those in the text, most noticeably in Book
II where the last four entries in the TOC are appropriately identified
as Sections II, III, IV, and V but the corresponding headings in the
text are incorrectly named as Section II Part I, Part II, Part III and
Part IV. TOC headings and text headings also vary in their specific
wording and the presence or absence of parentheses and dashes.
Inconsistent ways of expressing measurements are as in the original, for
example, one fifth of an inch, 1/5th of an inch, 1/5 of an inch, 1/5″ of
an inch, 1/5″.
The dimensions of many organisms are described using an archaic unit of
length: the ‘line’ which was equivalent to 1/12 of an inch. However, as
the inch itself varied, both within and between countries, it was a
non-standard measurement, e.g. in England one line was equivalent to
2.117 mm but the French (Paris) ligne was equal to 2.256 mm. The triple
prime symbol ‴ was used to represent the unit and occasionally appears
in this text (along with the more common ′ and ″ symbols representing
feet and inches). The ligne unit is still used by watchmakers.
The closing pages of the book contain advertising material about other
works from the same publisher. In some cases the date of publication
could not be determined with certainty because of the inferior quality
of the page scans.
PARASITES.
PARASITES;
A TREATISE ON THE
ENTOZOA OF MAN AND ANIMALS,
INCLUDING
SOME ACCOUNT OF THE ECTOZOA.
BY
T. SPENCER COBBOLD, M.D., F.R.S., F.L.S.,
HONORARY VICE-PRESIDENT OF THE BIRMINGHAM NATURAL HISTORY
AND MICROSCOPICAL SOCIETY.
[Illustration]
LONDON:
J. & A. CHURCHILL, NEW BURLINGTON STREET.
1879.
PREFACE
My introductory treatise on the Entozoa having long been out of print,
it occurred to me that instead of attempting another edition it would be
better to write an entirely new work, employing only such fragmentary
portions of the old treatise as would harmonise with the far wider
design I have now in view. Whilst, therefore, I have freely utilised
a selection of the illustrations given in the elementary volume,
comparatively few of its pages have been incorporated in the present
work.
Dealing with parasites and parasitism after a manner not hitherto
attempted I have purposely omitted minute anatomical descriptions,
and, with rare exceptions, I have avoided the introduction of clinical
details. While bringing to a focus the records of, and principal
references to, a widely scattered, intricate, and voluminous literature,
it has been my chief endeavour to supply abundance of original matter
of a kind that cannot be found in the columns of any existing treatise.
Whether I have succeeded or not the experienced helminthologist alone
can judge. He, at all events, will perceive that the summary, though
compressed within the space of a moderate-sized octavo, can only have
resulted from sustained effort.
This treatise is not professional, that is to say, it does not concern
itself with therapeutics or the curative treatment of parasitic
affections; yet it introduces and helps to solve many questions
relating to epidemics, endemics, and epizoötics due to parasites. The
medical man who only looks at the phenomena of parasitism as displayed
within the human territory must of necessity acquire a cramped, narrow,
and distorted conception of the rôle played by parasites in the
production of disease. Let it be freely granted that to the practising
physician, as such, it matters little how many beasts, birds, reptiles,
or fishes perish annually from parasitic affections; yet, when it is
demonstrable that a large proportion of the strictly human entozoa
require a change of hosts--or, in other words, need to pass through the
bodies of the lower animals--then it is evident that some acquaintance
on his part with the entozoa infesting animals becomes a practical
necessity. Knowledge of the kind here offered will often materially
aid him in recommending prophylactic measures. Moreover, the study of
comparative pathology, almost ignored in England, conveys with it other
lessons of high value in relation to the healing art. The great mind
of John Hunter comprehended all this long ago, as any student of the
beautiful preparations contained in the museum of the Royal College
of Surgeons may readily convince himself; and this is all the more
noteworthy, since the subject concerns the physician rather than the
surgeon.
To the naturalist the second half of this book addresses itself in a
very direct manner. When engaged in his dissections, an appeal to its
pages will often enable him to decide at once as to the species of
parasite accidentally encountered, and if a full diagnosis be demanded
it will guide him to better sources of information. Many hundreds of
correspondents, not having ready access to the systematic writings of
Rudolphi, Diesing, and Dujardin, have requested me to identify their
“finds.” I have rarely or never failed to comply with their requests;
but it is hoped that the present work may prove of ready service to
subsequent inquirers, and thus place a reasonable limit upon the number
of future applicants. Since the manuscript of this work was completed I
have received Dr von Linstow’s _Compendium der Helminthologie_, which,
for the purposes held in view by the author, leaves little to be desired.
Expressly to meet the requirements of the Sanitarian I have dwelt upon
the developmental phenomena exhibited by those parasites that occasion
fatal helminthiases; and, in this relation, I have not confined my
remarks to the parasites that are injurious to man in a direct manner,
but have extended my observations to the genesis of those entozoa that
prove destructive to horses, to beasts of burden generally, and to other
creatures which, like cats and dogs, are in various ways subservient
to man’s wants. It will be seen that in this way several questions
relating to the purity of water and flesh-food, respectively, have been
incidentally brought under notice.
In view of the magnitude of the task which my enthusiasm, perhaps
unwarrantable, has led me to undertake, I know full well how
considerately my foreign friends and correspondents will deal with
the errors of omission and commission that they will certainly detect
in these pages. If there be any educated persons at home who still
affect to despise the revelations of helminthology, I can assure them
that their prejudices are misplaced. The study of the structure and
economy of a humble parasite brings to the investigator no slight
insight into the workings of nature. If these workings cannot at all
times be pronounced to be “good and beautiful,” they must at least
be characterised as “true.” The knowledge of the true--especially if
that knowledge by its practical applications be calculated to confer
substantial benefits upon man and his inferior fellow-creatures--ought
to be held in high esteem; but, apart from this purely utilitarian view,
there remains for the investigator the delight occasioned by the in-rush
of new scientific ideas. The average mind, being either essentially
commercial or ridiculously sentimental, as the case may be, is totally
incapable of comprehending the motive power that animates and guides the
votary of science. The late Professor Faraday, a man wholly untinged by
the ambitions of wealth and power, once remarked to me that there were
no people so difficult to instruct as those who were ignorant of their
own ignorance. It is just these very persons who, when placed in high
positions of social, political, or professional trust, most powerfully
contribute to check a nation’s progress. There are too few genuine
workers at science in this country. As one of the rank and file, I claim
only to have honestly contributed my mite. I should like to see a small
army of helminthologists rise up and lay siege to the fortresses at
present securely held by thousands of death-dealing parasites.
T. S. C.
74, Portsdown Road, London
_May, 1879_.
SYNOPSIS OF CONTENTS.
PAGE
GENERAL INTRODUCTION 1
BOOK I.
PARASITES OF MAN.
SECTION I.--TREMATODA (FLUKES) 14
" II.--CESTODA (TAPEWORMS) 56
" III.--NEMATODA (ROUNDWORMS AND THREADWORMS) 149
" IV.--
PART I.--Acanthocephala (Thornheaded Worms) 256
" II.--Suctoria (Leeches) 257
" III.--Arachnida (Parasitic forms of) 259
" IV.--Crustacea (alleged Parasitic forms of) 268
" V.--Insecta (Parasitic forms of) 269
" VI.--Protozoa (Parasitic forms of) 276
APPENDIX (Statistics) 284
BOOK II.
PARASITES OF ANIMALS.
SECTION I.--PARASITES OF MAMMALIA.
PART I.--Parasites of Quadrumana 289
" II.--Parasites of Cheiroptera 293
" III.--Parasites of Insectivora 295
" IV.--Parasites of Carnivora 297
" V.--Parasites of Pinnipedia 313
" VI.--Parasites of Rodentia 315
" VII.--Parasites of Edentata 320
" VIII.--Parasites of Ruminantia 322
" IX.--Parasites of Solidungula 356
" X.--Parasites of Pachydermata 393
" XI.--Parasites of Cetacea and Sirenia 416
" XII.--Parasites of Marsupialia and Monotremata 430
" II.--PARASITES OF AVES 434
" III.--PARASITES OF REPTILIA 451
" IV.--PARASITES OF PISCES 457
" V.--PARASITES OF EVERTEBRATA 480
APPENDIX (Hæmatozoa) 485
INDEX 489
LIST OF BIBLIOGRAPHIES.
PAGE
No. 1. General and systematic treatises 8
2. Minor treatises, general memoirs, and monographs 10
3. Literature of _Fasciola hepatica_ in man 17
4. _Distoma lanceolatum_ in man 20
5. " _crassum_ 28
6. " _sinense_ 29
7. " _conjunctum_ in man 33
8. " _heterophyes_ 35
9. " _ophthalmobium_ 36
10. _Tetrastoma_ and _Hexathyridium_ 36
11. _Amphistoma hominis_ 38
12. _Bilharzia hæmatobia_ 55
13. _Tænia mediocanellata_ and the beef-measle 84
14. " _solium_ and the pork-measle 94
15. " _tenella_ and the mutton-measle 99
16. " _lophosoma_ 99
17. " _nana_ 100
18. Tapeworm varieties and monstrosities 105
19. _Bothriocephalus latus_, _B. cordatus_, and
_B. cristatus_ 112
20_a._ General literature of hydatids (English) 141
_b._ Hydatids of the liver 142
_c._ " " and other organs together 143
_d._ Liver hydatids. American cases 144
_e._ Hydatids of the lungs and pleura 144
_f._ " of the kidney 144
_g._ " of the spleen, omentum, and abdominal cavity 144
_h._ " within the pelvic cavity 145
_i._ " of the heart and blood-vessels 145
_k._ " of the brain and cranial cavity 145
_l._ " of the bones 145
_m._ " of the breast, muscles, and soft parts 146
_n._ " of uncertain seat 146
_o._ " of animals 147
_p._ " in man. Foreign literature 147
21. _Trichina spiralis._ English literature 174
" Foreign literature 177
22. _Trichocephalus dispar_ 180
23. _Filaria Bancrofti_ (_F. sanguinis hominis_) 202
Supplement (Hæmatozoa) 488
24. _Filaria loa_ 206
25. " _lentis_ 206
26. " _labialis_ 207
27. " _trachealis_ and _F. bronchialis_ 208
28. _Eustrongylus_ (_Strongylus_) _gigas_ 210
29. _Dochmius duodenalis_ 216
30. _Dracunculus medinensis_ 224
31. _Oxyuris vermicularis_ 232
32. _Leptodera_ (_Anguillula_) _stercoralis_ and
_L. intestinalis_ 235
33. _Ascaris mystax_ 241
34. " _lumbricoides_ 251
35. _Echinorhynchus gigas_ 257
36. _Sanguisuga medicinalis_ and other leeches 259
37. _Pentastoma tænioides_ and _P. constrictum_ 265
38. _Demodex_, _Sarcoptes_, and other Arachnidan ectozoa 268
39. _Gammarus pulex_ in man 269
40. Bugs, lice, and other insect parasites of man 275
41. _Psorospermiæ_, _Gregarinæ_, and other protozoa 283
42. _Entozoa_ of monkeys 293
43. " and ectozoa of bats 295
44. " of insectivorous mammals 297
45. " of carnivorous mammals 310
46. " of seals 315
47. " of rodents 320
48. " of sloths and ant-eaters 322
49. " of ruminants 352
50. " and ectozoa of solipeds 389
51. " " of elephants 400
52. " of rhinoceroses 402
53. " of the hippopotamus and tapir 403
54. " and ectozoa of swine 414
55. " of whales, dolphins, and dugongs 429
56. " of marsupial animals 434
57. " and ectozoa of birds 448
58. " of reptiles 456
59. " and ectozoa of fishes 477
60. " of insects, crustaceans, and mollusks 484
ERRATUM.
Page 296, line 24 from the top, for “in the glow-worm (_Glomeris_),”
read “in a myriapod (_Glomeris_) which is phosphorescent like the
glow-worm.”
PARASITES.
INTRODUCTION.
No person can derive advantage from the study of parasites unless the
subject be approached in a right frame of mind. In other words, the
student of helminthology must, as a primary discipline, dispossess
himself of all preconceived opinions whatsoever, and in an attitude of
child-like simplicity seek truth for its own sake. Unless the mind be
absolutely free and unfettered it cannot rightly interpret the facts of
this peculiar department of biological science. Those students who are
nervously anxious to reconcile the conclusions of modern science with
the ideas of their forefathers are certain to remain just as ignorant of
the true value and significance of nature-teachings as all their fathers
were.
Whether dealing with the external or internal forms, the study of
parasites of man and animals is practically one of boundless extent;
and there is probably no department of knowledge, possessing an equal
value in relation to the welfare of man and beast, that is so thoroughly
misunderstood by those who are directly concerned in the appreciation of
its revelations. This has arisen from a total misconception as to cause
and effect. Most people, not excluding even the votaries of the healing
art, following tradition, regard the internal parasites or entozoa as
creatures either directly resulting from certain diseased conditions
of their _hosts_ or as organisms which would not have existed if their
_bearers_ had been perfectly healthy. Nothing can be more absurd. Such a
conclusion is utterly at variance with all logical deduction from known
facts. It is, however, quite on a par with multitudes of other popular
delusions which, in spite of the advance of science, will probably never
become wholly eradicated from the public mind. People who hold these
notions either cannot or do not desire to reject a view which has for
them a dominating power almost equal to that of any known religious
dogma. In conversation I have repeatedly noticed this to be the case.
These people are the victims of educated ignorance and they will never
allow that parasites are natural developments, accomplishing ends or
parts of the orderly mystery which reigns everywhere. Some of then
still cling to the creed that the presence of parasites, of internal
ones at least, betokens evidence of Divine disfavor; and their minds
are troubled with all sorts of distressing and childish conceptions.
In the present age one would have thought that such ridiculous ideas
could not be seriously maintained; but instead of being relegated to
the limbo of similar “old wives’ fables” they dominate the opinions of
thousands of our so-called educated people. The genuine searcher after
truth does not need to be told that all preconceptions of this order
hopelessly obscure the mental vision. They operate to render a just and
adequate understanding of the science of helminthology impossible. The
biologist may say what he lists, but he knows perfectly well that the
superstitious mind will continue to ignore the precious and elevating
results of scientific research, and that it will perseveringly continue
to persuade itself that internal worms, parasites, and entozoa, of
whatever kind, belong to the category of “plagues” liable to be
distributed as special punishments for human wrong-doing.
As remarked in my previous treatise, the best way of studying the
entozoa is to regard them as collectively forming a peculiar _fauna_,
destined to occupy an equally peculiar territory. That territory is the
wide-spread domain of the interior of the bodies of man and animals.
Each bearer or “host” may be viewed as a continent, and each part or
viscus of his body may be regarded as a district. Each district has its
special attractions for particular parasitic forms; yet, at the same
time, neither the district nor the continent are suitable as permanent
resting-places for the invader. None of the internal parasites “continue
in one stay;” all have a tendency to roam; migration is the soul of
their prosperity; change of residence the essential of their existence;
whilst a blockade in the interior soon terminates in degeneration and
death. I repeat it. The entozoa constitute a specialised fauna. What
our native country is to ourselves, the bodies of animals are to them.
To attack, to invade, to infest, is their legitimate prerogative. Their
organisation, habits, and economy are expressly fashioned to this
end. How remarkable and complex is their structure, and how peculiar,
diverse, and varied are their ways and wanderings, the contents of this
volume will, I trust, sufficiently explain. The puerile horror which
even some scientific persons affect to display in regard to the subject
is altogether out of place. To the rightly balanced mind the study of
these much abused “worms” is just as attractive as any other section
of zoology. Helminthology opens up to our view many of the strangest
biological phenomena of which the human mind can take cognisance; whilst
a profound and extended knowledge of the subject, in all its bearings,
is calculated to secure to the community a rich practical reward by
enabling us to do effectual battle with not a few of the many ills of
life to which our flesh is heir.
Further on the general advantages to be derived from the study of
parasites I cannot here dilate, and it becomes the less necessary
that I should do so, since I have entered upon the subject very fully
elsewhere. The character of the present work, moreover, imposes
brevity. If the plan which I now propose to follow should not be deemed
altogether satisfactory from the purely zoological standpoint, it
will nevertheless have the advantage of simplicity and novelty; and
knowing full well the difficulties that must surround any attempt to
give a perfect classification of the entozoa, considered as a natural
group, I feel sure that my helminthological friends will credit me with
exercising a wise discretion in selecting the simplest available method
of arrangement. My plan, therefore, is to devote separate sections of
this work to the parasites of the different classes of vertebrated
animals, including man, treating of the various species in regular
succession. This arrangement is merely one of convenience and has no
reference whatever to conceptions of zoological equivalency as variously
interpreted and maintained by authors and investigators. The parasitic
groups will be taken up in the following order, quite irrespective of
their relative importance, and also without any attempt to treat each
group with equal fulness. In the matter of recent literature only will
the present record and summary make any approach toward completeness, my
hope being to render this treatise indispensable and trustworthy as a
ready means of reference.
I. FLUKES. TREMATODA.--This group embraces several families of
parenchymatous worms. The various species exhibit one or more
suckers, which the older naturalists regarded as so many mouths or
_perforations_. Hence the ordinal title. The term fluke is of Saxon
origin, meaning anything flat. Thus, it has been applied to sole-fish
or flounders, to the flattened halves of the tail of cetaceans, to the
blades of anchors, and so forth. Although the common liver fluke is
flat, many species of the order are round, biconvex, or even filiform
organisms. I recognise six families:--_Monostomidæ_, _Distomidæ_,
_Amphistomidæ_, _Tristomidæ_, _Polystomidæ_, and _Gyrodactylidæ_. Most
of the species are entozoal; but many adhere to the surface of the body
of piscine hosts.
II. TAPEWORMS. CESTODA.--This comprises not only the tapeworms, but
also the measles and other bladder-worms or cystic Entozoa of the old
authors (Cystica). The Greek word _kestos_ means a band or girdle;
hence the ordinal term above given. The bladder-worms, including
Hydatids, Cysticerci, &c., are the larval stages of growth of various
tapeworms. The further reduction of this order into sub-orders or
families requires careful attention. At present we have _Tæniadæ_,
_Acanthotæniadæ_, _Dibothridæ (= Bothriocephalidæ)_, _Diphyllobothridæ_,
_Tetrarhynchidæ_, and _Tetraphyllobothridæ_. All the genera and species
are entozoal. The proposal to separate the snouted or proboscidiform
tapeworms (_Rhynchotæniadæ_) from those in which the rostellum is absent
(_Arhynchotæniadæ_) does not recommend itself to my judgment.
III. ROUNDWORMS. NEMATODA.--This series comprises not only lumbricoid
or roundworms proper, but also threadworms. The term derives its origin
from the Greek word _nema_, signifying a thread. It likewise includes
the strongyles, the term _strongulos_ meaning round or cylindrical.
This is a very extensive group whose parasitic members are strictly
entozoal, whilst the non-parasitic forms are either entirely free or
they infest plants. Some of the so-called free nematoids live in the
slime of animals. The artificial classification by Schneider, based
on the muscular system, places these parasites in three well-marked
groups, but I think it a disadvantage to separate widely many really
closely allied forms. Thus, in his _Polymyarii_ we have the genus
Enstrongylus, and in his _Meromyarii_ the Strongyli proper. Most of the
genera may be fairly included in the following families:--_Ascaridæ_,
_Cheiracanthidæ_, _Cucullanidæ_, _Strongylidæ_, _Trichinidæ_,
_Oxyuridæ_, _Trichocephalidæ_, _Filaridæ_, _Gordiidæ_, _Anguillulidæ_.
IV. THORNHEADED-WORMS. ACANTHOCEPHALA.--This group embraces a small
series of parasites, which, in general appearance, resemble the nematode
worms. They differ, however, essentially, being, as the term indicates,
furnished with spine-covered heads. They are, moreover, destitute
of digestive organs. The species are entozoal in habit, abounding
particularly in fishes and reptiles. At present, all the known forms are
included in one family (_Echinorhynchidæ_), which also comprises only a
single genus.
V. ANNELID PARASITES. SUCTORIA.--In this category one must place all
such suctorial annelids as affix themselves to hosts for a longer or
shorter period. Many of the leech-like parasites (_Clepsinidæ_, and
especially _Malacobdellidæ_) remind one of certain flukes (_Tristoma_,
&c.) possessing ectozoal habits; whilst the leeches, properly so called,
afford instances of the passage from a semi-parasitic to what has been
called the free parasitic mode of existence. In tropical countries these
creatures very readily attach themselves to man and animals, often
creating severe distress. The genera _Clepsine_ and _Hæmocharis_ attack
mollusks and fishes respectively. The species are all ectoparasitic and
exceedingly numerous. They cannot be described in this work.
VI. ARACHNID PARASITES, ARACHNIDA (part of).--The great class of
articulated, limb-jointed, or, more strictly, arthropodous animals,
includes a variety of parasites. The mites, true ticks, and such like
creatures, belong to this group. Some few of them are entozoal in
habit, others are only partially so, whilst the majority are entirely
ectozoal. Of the two great sections of Arachnida, namely, Pulmonaria
and Trachearia, the latter alone contains strictly parasitic forms. The
parasitic species belong to the following families:--_Pentastomidæ_,
_Pycnogonidæ_, _Ixodidæ_, _Acaridæ_, _Gamasidæ_, _Hydrachnidæ_,
_Solpugidæ_. The parasitism of some of the species is very partial or
slight. Thus, certain of the water mites, in their juvenile state,
dwell on aquatic insects only; and the tick-like _Gamasidæ_ occur upon
dung-beetles. The other ectozoal species attack vertebrated animals, and
several attach themselves to man himself. The whale lice (_Cyamidæ_) are
here included in the _Pycnogonidæ_, though often placed by zoologists
with the Crustaceans.
VII. CRUSTACEAN PARASITES. CRUSTACEA (part of).--A large number of
species belonging to various well-marked sections of this great class
of Invertebrates are parasitic in their habits, most of them being
comprised in the so-called haustellated group. They are familiarly
known to zoologists as Epizoa. As this latter term implies, they are
strictly ectozoal in character, most of the species victimising fishes
by attaching themselves, not only to the general surface of the body,
but also to the eyes, and especially to the gills or branchiæ. The
species for the most part belong to the families _Lernæidæ_, _Caligidæ_,
_Dichelestidæ_, and _Argulidæ_. In this category must likewise be placed
two other families belonging to the so-called isopodous section of
edriophthalmatous crustaceans. These are the _Cymothoidæ_, which attach
themselves to the tails of fishes, and the _Bopyridæ_, which occupy
the branchial cavity of shrimps. The nature of this work precludes any
detailed notice of the numerous members of this section.
VIII. INSECT PARASITES. INSECTA (part of).--The insects, properly so
called (that is to say, arthropodous, evertebrated creatures, with six
legs), are many of them essentially parasitic in their habits. The most
important of these are “bots” and other larvæ or maggots of various
flies (Diptera). The varieties of lice are also included in this group.
Some few of the insect parasites are strictly entozoal in habit, at
least for a part of their lifetime, being previously attached externally
for a short period only. Most of the forms are essentially ectozoal. A
very large number of insect tormentors, although deriving nourishment
from their victims, attach themselves to the animals for so short a time
that they cannot be classed as parasites under the ordinary acceptation
of the term. As examples of the so-called free parasitism, the autumnal
flies (_Tabanidæ_) and _Stomoxys_ may be cited. Although embracing
but few strictly parasitic forms we have the following:--_Œstridæ_,
_Hippoboscidæ_ (with _Melophagus_), and _Nycteribiidæ_. In regard to the
maggots of _Muscidæ_ and _Sarcophagæ_, some of them are parasitic on
animals and man, whilst others are parasitic upon insects themselves.
The larvæ of _Conopidæ_ attack humble-bees internally. Those parasitic
insects, properly so called, which, like certain of the crustaceans,
are sometimes spoken of as epizoa, comprise three well-marked families.
Thus, we have Pediculidæ (the source of lousiness), _Philopteridæ_, and
_Liotheidæ_. Both of the latter embrace numerous species which for the
most part content themselves with devouring the feathers of birds and
the hairs of quadrupeds. In addition to these it may be added that some
of the rat-tailed larvæ or Helophilus maggots (_Syrphidæ_) are parasitic
in man and quadrupeds, as are also the larvæ of the churchyard beetle
(_Blaptidæ_). The closely allied _Tenebrionidæ_ and other coleopterous
families also supply various maggots possessed of parasitic habits.
Fleas and bugs come under Van Beneden’s category of free parasites. This
is equivalent to calling them non-parasitic parasites, an expression
which looks very like a contradiction of terms.
IX. PROTOZOAL PARASITES. PROTOZOA (part of.)--This miscellaneous
assemblage of minute creatures embraces a number of parasites of very
low organisation. In the present work it is neither desirable nor
necessary to hazard any statements respecting their precise zoological
position. It is sufficient to say that the parasitic protozoa are
for the most part entozoal in habit, not a few of them possessing
vegetable affinities. The microscopic _Bacteridæ_, _Gregarinidæ_, and
_Psorospermiæ_, comprise a multitude of organisms which are strictly
parasitic in their habits, whilst amongst the _Infusoria_ we find
numerous forms which, though dwelling in the intestinal canal of their
hosts, do not derive nourishment in a direct manner from their bearers.
Of this kind are _Paramecium_ and _Balantidium_. The separation of the
psorospermiæ and gregarinæ into genera is attended with difficulty;
nevertheless, I have for convenience long recognised various types
under titles corresponding with the names of the observers who first
discovered them (_Hesslingia_, _Gubleria_, _Lindermannia_, and so
forth). Of necessity, the protozoal parasites will only be incidentally
noticed in this work. In this category I place the falsely so called
“cattle-plague bodies.” The micrococci and bacteria hardly come within
the province of the helminthologist.
Without prejudice to the foregoing restrictions I must at the same time
observe that the varied characters presented by the above-mentioned
groups show how impossible it is to treat the subject of parasitism
adequately, if one is obliged to confine his remarks to the internal
parasites or helminths proper. Many creatures possessed of entozoal and
ectozoal habits are parasites in every legitimate sense of the term, and
yet they do not belong to the class _Helmintha_ in its common zoological
acceptation. _That_ class taken by itself may still be allowed to stand
pretty much as I represented it in 1864; but in the present work I
cease to speak of the Entozoa as in any sense the zoological equivalent
of the _Helmintha_. I prefer to employ the term Entozoa in its popular
and wider acceptation. It conveniently stands thus, moreover, in direct
contradiction to the term Ectozoa.
As this work treats of parasites only, I purposely refrain from dealing
with the Turbellarians, and certain other creatures usually classed with
_Vermes_. The vague term “worms,” so often employed as the equivalent
of _Helmintha_, is misleading in many ways. I should like to see it
adopted only when speaking of the Annelids proper. It would still have
a sufficiently wide application, seeing that it would include Leeches,
Earth-worms, Naids, Tubed-worms, Sea-lobworms, Sea-mice, Nereids, and a
host of other setigerous species. Notwithstanding the remote connection
subsisting between “intestinal worms” and worms properly so called,
the notion that an intimate relation subsists between the lumbricoid
helminths and earth-worms will probably never entirely disappear from
the popular or even from the professional mind.
Since one of the principal features of this treatise is to afford
a handy means of reference to the rich and extended literature of
parasitism, I here subjoin a list of general and systematic treatises.
To most of these I shall constantly refer. Full special references to
detached memoirs will appear in the bibliographies scattered throughout
the body of the work.
BIBLIOGRAPHY (No. 1).--_Bremser_, ‘Ueber lebende Würmer im lebenden
Menschen,’ Vienna, 1819; French edit., by Grundler, 1824.--_Idem_,
‘Icones helminthium,’ Vienna, 1824.--_Cobbold, T. S._, ‘Entozoa,
an Introduction to the Study of Helminthology, with reference
more particularly to the Parasites of Man,’ London, 1864; Supp.,
1869.--Reviews in the ‘Lancet,’ Sept. 24th, 1864, p. 353; in the
‘Med. Times and Gaz.,’ Oct. 29th, 1864, p. 474; in the ‘Athenæum,’
Oct. 15th, 1864, p. 493; in ‘Cosmos,’ Oct. 27th, 1864, p. 463; in the
‘Reader,’ Nov. 26th, 1864, p. 668; in the ‘Edinburgh Vet. Review,’
Nov., 1864, p. 662; in ‘Intellectual Observer,’ vol. vi, 1864, p. 190;
in the ‘Quarterly Journal of Science,’ No. v, January, 1865, p. 145;
in the ‘Quart. Journ. of Micr. Science,’ New Series, No. 17, Jan.,
1865, p. 43; in ‘Popular Science Review,’ Jan., 1865, p. 214; in the
‘Veterinarian,’ Feb., 1865, p. 97; in the ‘Medical Mirror,’ Jan.,
1865, p. 23; in the ‘Natural History Review’ for July, 1865; in the
‘British and Foreign Medico-Chirurgical Review,’ April, 1865, in the
‘Edinburgh Medical Journal’ for April, p. 929; in the ‘Social Science
Review’ for Feb. 1, 1866, p. 169; in ‘Dublin Quart. Journ. of Medical
Science’ for Aug., 1867.--_Davaine, C._, ‘Traité des Entozoaires et des
maladies vermineuses de l’homme et des animaux domestiques,’ Paris,
1860, 2nd edit., 1877-79.--_Diesing, C. M._, ‘Systema helminthum,’
Vienna, 1850.--_Dujardin, F._, ‘Histoire naturelle des helminthes
ou vers intestineaux,’ Paris, 1845.--_Goeze, T. A. S._, ‘Versuch
einer Naturgeschichte der Eingeweidewürmer thierischer Körper,’
Blankenburgh, 1782.--_Küchenmeister, F._, ‘Die in und an dem Körper des
lebenden Menschen vorkommenden Parasiten,’ Leipsic, 1855, 2nd. edit.,
1878-79; Eng. edit., by Lankester, 1857.--_Le Clerc, D._, ‘A Natural
and medicinal History of Worms bred in the bodies of men and other
animals’ (_sic_), Browne’s edit., London, 1721.--_Leuckart, R._, ‘Die
menschlichen Parasiten, und die von ihren herruhrenden Krankheiten,’
Leipsic und Heidelberg, 1863-1876.--_Redi, F._, ‘De animalculis vivis
quæ in corporibus animalium vivorum reperiuntur, observationes;’ Coste’s
edition, Amstelædami, 1688.--_Rudolphi, C. A._, ‘Entozoorum sive vermium
intestinalium historia naturalis,’ Amsterdam, 1808.--_Idem_, ‘Entozoorum
Synopsis,’ Berlin, 1819.--_Van Beneden, P. J._, ‘Animal Parasites and
Messmates,’ London, 1876.
Several of the above works, while professing to deal with human
parasites only, cover more or less of the whole ground of helminthology.
Leuckart’s work is invaluable in this respect; and in the matter of
literary references of a professional kind Davaine’s treatise is itself
well nigh exhaustive. In any ordinary volume it is not possible to
give a complete bibliography of parasitism. I make no pretension to
do so here; nevertheless, the large number of modern memoirs that I
have received from the distinguished writers themselves, enables me to
render this part of my book very useful. As second only in importance
to the above-mentioned works may be added the following--whether minor
treatises, memoirs, monographs, comprehensive articles, or reports of a
general or special character, respectively. As such it will be seen that
some of them are sufficiently comprehensive, and their mere enumeration
will enable the beginner to realise something like a fair estimate of
the scope of helminthology. In the case of my own works I have ventured
to add references to reviews and notices, because many of the latter
contain valuable original suggestions made by the various anonymous
writers.
BIBLIOGRAPHY (No. 2).--_Bastian, H. C._, “On the Anatomy and Physiology
of the Nematoids, parasitic and free,” ‘Philosophical Transactions,’
1865 (see also Bibliog., No. 60).--_Cobbold, T. S._, ‘Worms; a series of
lectures on Practical Helminthology,’ London, 1872; Italian edition by
Tommasi. Milan, Florence, &c., 1873.--_Idem_, ‘The Internal Parasites
of our Domesticated Animals,’ London, 1873; Italian edit. by Tommasi,
Florence, 1874.--_Idem_, ‘Tapeworms (Human), their Sources, Varieties,
and Treatment,’ London, 3rd edit., 1875. Reviews (1st and 2nd edit.,
with ‘Threadworms’), in ‘Brit. and For. Med.-Chir. Review’ for 1867,
p. 433; in ‘Edin. Med. Journ.’ for 1866-67, p. 107; in ‘Lancet,’
Nov. 10th, 1866; in ‘Popular Science Review,’ Oct. 1st, 1866; in
‘Intellectual Observer,’ Oct. 1866; in ‘Med. Press and Circular,’
Jan. 16th, 1867; again in the ‘Lancet,’ for March 13th, 1867; and in
‘Dublin Quart. Journ. of Medical Science’ for 1867, 3rd edit.; in the
‘Field,’ Sept. 25th, 1875; and in ‘Popular Science Review’ for Jan.,
1876.--_Idem_, ‘Catalogue of the Specimens of Entozoa in the Museum
of the Royal College of Surgeons of England,’ London, 1866; noticed
in the ‘Lancet’ for March 24th, 1866, p. 321.--_Idem_, “On the best
Methods of displaying Entozoa in Museums,” ‘Journ. Linn. Soc.,’ vol.
viii, p. 170.--_Idem_, ‘New Entozootic Malady,’ &c., 1864; popular
brochure, reviewed in the ‘Lancet,’ Feb. 4th, 1865, p. 128; in the
‘Athenæum,’ Jan. 21st, 1865, p. 87; in the ‘British Med. Journal,’
Jan., 1865; in the ‘Veterinary Review and Stockowners’ Journal,’ No.
2, New Series, Feb., 1865, p. 76; in the ‘Reader,’ Feb. 4th, 1865, p.
142; in ‘Med. Times and Gaz.’ for June 2nd, 1865; in the ‘Field’ for
March 18th, 1865.--_Idem_, “Parasites of Man,” forming a series of
articles contributed to the ‘Midland Naturalist,’ 1878-79.--_Idem_,
“Notes on Entozoa contained in the various Metropolitan Museums,” in
‘Lancet,’ May 13th, 1865, p. 503.--_Idem_, “Report on _Plica polonica_,
in reference to Parasites,” in ‘Pathological Soc. Trans.,’ 1866, p.
419.--_Idem_, “Report on Experiments respecting the Development and
Migrations of the Entozoa,” ‘British Assoc. Reports’ (Bath Meeting)
for 1864, p. 111; and briefly noticed in ‘Lancet’ for Sept. 24th,
1864.--_Idem_, Miscellaneous observations, including “Note on Parasites
in the Lower Animals,” in ‘Dub. Med. Press’ for Feb. 11th, 1863, p.
154.--_Idem_, “Vegetables, Fruits, and Water considered as sources of
Intestinal Worms;” in the ‘Popular Science Review’ for Jan., 1865, p.
163.--_Idem_ (anonymously), “On Comparative Pathology and Therapeutics”
(in relation to Entozoötics); leading art. in ‘Lancet’ for Dec. 9th,
1865, p. 652.--_Idem_, “List of Entozoa, including Pentastomes, from
animals dying at the Zoological Society’s Menagerie, between 1857-60
inclusive, with descriptions of several new species,” ‘Proc. Zool.
Soc.,’ 1861.--_Idem_, “Remarks on all the Human Entozoa,” ‘Proc. Zool.
Soc.,’ 1862; abstracts in ‘Brit. Med. Journ.’ for 1862, and in ‘Edinb.
New Phil. Journ.,’ vol. xvii, new series, 1863, p. 145; in Report of
the ‘Proceed. of the Brit. Assoc. at Cambridge,’ 1862.--_Idem_, “Our
Food-producing Ruminants, and the Parasites which reside in them;
being the Cantor Lectures of the Society for the Encouragement of
Arts, Manufactures, and Commerce,” delivered in 1871, and pub. in the
‘Journal of the Soc. of Arts’ for that year.--_Davaine, C._, “Les
Cestoïdes,” in ‘Dict. Encycl. des Sci. Med.,’ Paris, 1876.--_Eberth,
C. J._, ‘Untersuchungen ueber Nematoden,’ Leipsic, 1863.--_Heller,
A._, “Darmschmarotzer,” in Von Ziemssen’s ‘Handbuch,’ Bd. vii, 1876;
and in the American edition of the same, 1877.--_Jones, T. R._, “List
of Entozoa of Greenland,” taken from _Krabbe_; ‘Arctic Manual,’ 1875,
p. 179.--_Krabbe, H._, ‘Helminthologiske Undersogelser,’ Copenhagen,
1865.--_Leuckart, R._, ‘Die Blasenbandwürmer und ihre Entwicklung,’
Giessen, 1856.--_Moquin-Tandon, A._, “Epizoa and Entozoa,” in Hulme’s
edit. of his ‘Elements of Medical Zoology,’ London, 1871.--_Nordmann,
A. von_, ‘Mikrographische Beiträge zur Naturgeschichte der wirbellosen
Thiere,’ Berlin, 1832.--_Olsson, P._, “Entozoa, iakttagna hos
Skandanaviska hafsfiskar.,” Lund, ‘Univ. Årsskrift,’ 1867.--_Owen,
R._, “Entozoa,” art. in Todd’s ‘Cyclopædia of Anat. and Physiol.,’
London, 1839.--_Idem_, “Entozoa,” ‘Lectures (iv and v) on the
Comp. Anat. and Physiol. of the Invertebrate Animals,’ London,
1855.--_Pagenstecher, H. A._, ‘Trematodenlarven und Trematoden,’
Heidelberg, 1857.--_Rhind, W._, ‘A Treatise on the Nature and Cure of
Intestinal Worms, &c.,’ London, 1829.--_Rolleston, G._, “Characteristics
of Nematelminthes and Platyelminthes,” in his ‘Forms of Animal
Life,’ Oxford, 1870.--_Schneider, A._, ‘Monographie der Nematoden,’
Berlin, 1866.--_Siebold, C. von._, “Parasiten,” art. in Wagener’s
‘Handwörterbuch der Physiol., &c.,’ 1845.--_Idem_, “Helminthes,” Book
v, in Burnett’s edit. of Siebold and Stannius’ ‘Comparative Anatomy,’
London and Boston, 1854.--_Thomson, A._, “Entozoa,” in the art. “Ovum,”
in Todd’s ‘Cyclop. of Anat. and Physiol.,’ London, 1859.--_Van Beneden,
P. J._, ‘Mémoire sur les Vers Intestineaux,’ Paris, 1858.--_Idem_, “Les
Vers Cestoïdes,” ‘Mém. de l’Acad. Roy.,’ Brussels, 1850.--_Verrill,
A. E._, “The External and Internal Parasites of Man and the Domestic
Animals,” ‘Rep. of Board of Agriculture,’ Connecticut, U.S., 1870.--_Von
Baer, K. E._, ‘Observations on Entozoa;’ in an analytical notice of
his article “Beiträge zur Kentniss der niedern Thiere,” from ‘Nova
Acta Nat. Cur.,’ tom. xiii, in the ‘Zool. Journ.,’ vol. iv, p. 250,
1828-29.--_Wagener, G. R._, ‘Beiträge zur Entwicklungsgeschichte der
Eingeweidewürmer,’ Haarlem, 1857.--_Weinland, D. F._, ‘An Essay on the
Tapeworms of Man,’ Cambridge, U.S., 1858.
BOOK I.
PARASITES OF MAN.
Whatever notions people may entertain respecting the dignity of the
human race, there is no gainsaying the fact that we share with the lower
animals the rather humiliating privilege and prerogative of entertaining
a great variety of parasites. These are for the most part entozoal in
habit. As the parasites are apt to cause suffering to the bearer, a
superstitious age sought to interpret their presence as having some
connection with human wrong-doing. We can now afford to smile at such
erroneous ideas. The intimate relation subsisting between parasitic
forms dwelling in man and animals, and their interdependence upon one
another, alone suffices to preclude the idea that parasites have been
arbitrarily placed within the human bearer. It would seem, indeed, that
our existence is essential to the welfare and propagation of certain
species of parasites. Possibly it is only by accepting the hypothesis
of “Natural Selection” that we can escape the somewhat undignified
conclusion that the entozoa were expressly created to dwell in us, and
also that we were in part designed and destined to entertain them. View
the matter as we may, the internal parasites of man and animals strictly
conform to a few well-known types of structure, but these types branch
out into infinitely varied specific forms. The vulgar mind sees nothing
attractive in the morphology and organisation of a parasitic worm, and
common-place conceptions of the beautiful cannot be expected to embrace
within their narrow grasp the marvelous harmony and order that pervade
the structure and economy of the individual members of this remarkable
class of beings.
SECTION I.--TREMATODA (Flukes).
_Fasciola hepatica_, Linneus.--The first form I have to consider is
the common liver fluke. The part this entozoon plays in the production
of disease will be fully stated when treating of the parasites of the
sheep and other ruminants. About twenty instances of its occurrence
in the human body have been recorded. It has been found beneath the
skin in the sole of the foot (Giesker), and also under the scalp
(Harris), and behind the ear (Fox). Its more frequent seat is in the
liver and gall-ducts (Pallas, Brera, Bidloo, Malpighi) and gall-bladder
(Partridge). The alleged cases by Bauhin, Wepfer, and Chabert are
spurious, as is probably also that given by Mehlis. Duval’s case appears
to be genuine, but the occurrence of the worm in the portal vein was
accidental. Dr Murchison has recorded a case, occurring at St Thomas’s
Hospital, where a solitary specimen was found in the liver. Dr H. V.
Carter also met with the worm in a young Hindoo.
In the second half of the present work I shall reproduce Blanchard’s
admirable figure of the sexually mature worm (Fig. 61), accompanied
by a categorical statement respecting the known facts of development.
In this place, however, I may observe that the cases recorded by
Giesker, Harris, and Fox had clearly pointed to the circumstance that
the higher larvæ of this fluke must be armed cercariæ, otherwise they
could not have bored their way through the human skin. As we shall
see, Dr Willemoes-Suhm’s investigations have furnished evidence as to
the truth of this supposition. For anatomical details I refer to my
introductory treatise. In the adult state the liver fluke has been known
from the earliest times. We have clear evidences that it was described
by Gabucinus in the year 1547, and also subsequently by Cornelius Gemma,
who, in a work published some thirty years later, refers to an epizootic
disease prevalent in Holland during the year 1552, and which was very
justly attributed to the parasite in question. After this date many
writers described the liver fluke more or less accurately, and entire
volumes were devoted to the consideration of the formidable disease
which it occasions. The nomenclature of the parasite has been a subject
of controversy. Amongst naturalists in general the common liver fluke
is often described under the combined generic and specific name of
_Distoma hepaticum_; but the title is both incorrect and inappropriate.
The proper generic appellation of this parasite is _Fasciola_, as
first proposed by the illustrious Linneus (1767) and subsequently
adopted by F. Müller (1787), Brera (1811), Ramdohr (1814), and others.
Unfortunately Retzius (1786) and Zeder (1800) changed the generic
title without good cause, and the majority of writers, following their
authority, refused to employ the original name, although a consideration
of the distinctive types of structure severally displayed by the genera
_Distoma_ and _Fasciola_ fairly demanded the retention of the Linnean
title. In later times M. Blanchard (1847) strongly advocated the
original nomenclature, and I have myself continually urged its adoption.
On somewhat different grounds Professor Moquin-Tandon followed the same
course.
In the sexually mature state the liver fluke commonly measures three
fourths of an inch in length, occasionally reaching an entire inch or
even sixteen lines; its greatest breadth also varying from half an
inch to seven or eight lines transversely; body very flat, presenting
distinct dorsal and ventral surfaces, frequently curled toward the
latter during life; upper or anterior end suddenly constricted, produced
and pointed in the centre, forming the so-called head and neck;
posterior extremity less acuminated, sometimes rounded, or even slightly
truncated; margins smooth, occasionally a little undulated, especially
towards the upper part; oral sucker terminal, oval, rather smaller than
the ventral acetabulum, which is placed immediately below the root of
the neck; reproductive orifices in the middle line, a little below the
oral sucker; intromittent organ usually protruded and spirally curved;
a central, light-coloured space, covering two thirds of the body from
above downwards, marks the region of the internal male reproductive
organs, being bordered on either side and below by a continuous dark
band, indicating the position of the so-called yolk-forming organs; a
small, brown-coloured, rosette-like body situated directly below the
ventral acetabulum, marks the limits of the uterine duct; a series of
dark lines, branching downwards and outwards on either side, indicate
the position of the digestive organs; general color of the body pale
brownish yellow, with a slight rose tint. The surface of the body,
though smooth to the naked eye, is clothed throughout with small
epidermal spines which diminish in size towards the tail.
If any argument were necessary to show how desirable it is to
furnish full descriptions of the commoner kinds of parasite, I could
adduce numerous instances that have been brought under my notice
where professional men and others have been entirely mistaken as to
the essential nature of their parasitic finds. Thus, I have known an
instance where a great authority on the diseases of dogs has persisted
in asserting for the free proglottides of a tapeworm a nematode origin;
and, in like manner, human tapeworm-segments have frequently been
mistaken for independent fluke parasites. One of the most remarkable
instances of this kind is that which I have elsewhere described as
an error on the part of Dr Chabert. My reasons for so regarding his
interpretation of the facts observed by him stand as follows:
In the ‘Boston Medical and Surgical Journal’ for the years 1852-53-54,
Dr J. X. Chabert described several cases of Tænia, and he averred that
the tapeworms were associated with numerous specimens of _Distoma
hepaticum_. The passage of distomes by patients during life was even
regarded by Dr Chabert as indicative of the presence of Tænia within
the intestines. Surely, I remarked, Dr Chabert was mistaken. Are not
these so-called distomes the well-known _proglottides_? Not willingly
doubting Dr Chabert’s statements, but desirous, if possible, of
verifying the accuracy of his conclusions, I wrote to him (March 22nd,
1864) requesting the loan of a specimen, but I was not fortunate enough
to receive a reply. In the “Case of Tænia” in a boy four and a half
years old, given in the 49th vol. of the journal, Dr Chabert writes as
follows:--“In consequence of his passing the _Distoma hepaticum_, I
concluded he must be afflicted with Tænia.” Further on it is added, that
the administration of an astringent injection “caused the discharge of
innumerable small worms (_Distoma hepaticum_).” I think this is quite
decisive. The idea of “innumerable” flukes being expelled in this way is
altogether out of the question.
The only genuine case in which any considerable number of Distomata,
of this species, have been observed in the human subject is the one
recently recorded by Dr Prunac. In this instance two flukes were vomited
along with blood immediately after the administration of salines (sel
de Seignette), and about thirty were passed per anum. On the following
day, some tapeworm proglottides having been evacuated, both salts and
male-fern extract were administered. This caused the expulsion of an
entire tapeworm, and also about twenty more flukes. Notwithstanding
this successful treatment the hæmatemesis returned in about a month,
when, finally, three more flukes were vomited and the bleeding ceased.
Had not the parasites been submitted for identification to a competent
observer (Prof. Martins, of Montpellier), some doubt might have been
entertained as to the genuineness of this remarkable case. In reference
to Dr Prunac’s comments on the facts of fluke-parasitism in man, I will
only remark that Dr Kerr’s Chinese cases, to which he refers, were
probably due to _Distoma crassum_ and not to _D. hepaticum_. The Chinese
flukes will be noticed below.
BIBLIOGRAPHY (No. 3).--Full references to details of the cases by
Partridge, Fox, and Harris are given in Appendix B. to Lankester’s
Edit. of _Küchenmeister’s_ Manual. See also the works of Davaine and
_Leuckart_ (_l. c._ Bibl. No. 1).--_Carter, H. V._, “Note on _Distoma
hepaticum_” (from a patient under the care of Mr Pandoorung), ‘Bombay
Med. and Physical Soc. Trans.’ (Appendix), 1862.--_Chabert, J. X._
(quoted above). Murchison, C., ‘Clinical Lectures on Diseases of the
Liver,’ (2nd Edit., Appendix), London, 1877.--_Prunac_, De la Douve ou
Distome hépatique chez l’homme; in ‘Gazette des Hôpitaux’ for December,
1878 (p. 1147). For further references in this work, see Bibliog. No. 49.
_Distoma lanceolatum_, Mehlis.--At least three instances of the
occurrence of this small fluke in the human body have been observed.
The authority for these cases rests, severally, with Bucholz, who
found them in the gall bladder in considerable numbers at Weimar; with
Chabert, who expelled a large number from the intestines of a girl in
France; and with Küchner, who obtained forty-seven specimens from a
girl in Bohemia. Probably many similar instances have been overlooked,
and Küchenmeister hints that Duval’s parasites (above mentioned) may
have been this species. Although this worm will again be incidentally
noticed in connection with bovine parasites (and its ciliated larvæ
will also be referred to when discussing the characters of the embryo
of Bilharzia), I here subjoin a diagnosis of the characters of the
adult parasite. The lancet-shaped liver fluke is a small flat helminth,
measuring rather more than the third of an inch in length, and about
one line and a half in breadth, being also especially characterised by
its lanceolate form; the widest part of the body corresponds with a
transverse line drawn across the spot where the vitellaria terminate
below, and from this point, on either side, the width of the animal
becomes gradually narrowed towards the extremities; both ends are
pointed, but the inferior or caudal one more obtusely than the anterior
or oral end; the general surface is smooth throughout, and unarmed; the
reproductive orifices are placed in the central line immediately in
front of the ventral sucker, and below the point at which the intestine
bifurcates; the oral sucker is nearly terminal, and 1/50″ in breadth,
the ventral acetabulum being about the same diameter; the testes form
two lobed organs placed one in front of the other in the middle line
of the body and directly below the ventral sucker; the uterine canal
is remarkably long, forming a series of tolerably regular folds, which
occupy the central and hinder parts of the body, reaching almost to
the caudal extremity. The vitelligene glands cover a limited space, on
either side of the centre of the body near the margin. The _foramen
caudale_ communicates with a contractile vesicle, which passes upwards
in the form of a central trunk-vessel, early dividing into two main
branches; these latter reach as far forwards as the œsophageal bulb,
opposite which organ they suddenly curve upon themselves, retracing
their course for a considerable distance backwards; the digestive canals
are slightly widened towards their lower ends, which occupy a line
nearly corresponding with the commencement of the lower fifth of the
body; the ova are conspicuous within the uterine folds, which present a
dark brownish color in front, passing to a pale yellow color below.
[Illustration: FIG. 1.--The lancet-shaped fluke (_Distoma lanceolatum_),
showing the disposition of the digestive and reproductive organs
internally. Viewed from behind; mag. about 12 diameters. After
Blanchard.]
In reference to Kichner’s remarkable case I reproduce an abstract of it
from Leuckart’s account (‘Die menschlichen Parasiten,’ Bd. i, s. 608),
the original particulars of which were communicated to Leuckart by Dr
Kichner himself:--
“Dr Kichner’s patient was a young girl, the daughter of the parish
shepherd at Kaplitz, having been accustomed to look after the sheep
ever since she was nine years old. The pasture where the animals
fed was enclosed by woods, being traversed by two water dykes, and
being, moreover, also supplied by ten little stagnant pools. These
reservoirs harboured numerous amphibia and mollusks (such as _Lymnæus_
and _Paludina_), and the child often quenched her thirst from the half
putrid water. Probably she also partook of the watercresses growing in
the ditches. At length her abdomen became much distended, the limbs much
emaciated, and her strength declined. Half a year before death she was
confined to her bed, being all the while shamefully maltreated by her
step-mother. Dr Kichner only saw her three days before her death, and
ascertained that she had complained of pain (for several years) over the
region of the liver. A _sectio cadaveris_ was ordered by the Government,
when (in addition to the external evidences of the cruel violence to
which the poor creature had been subjected) it was found that she had
an enormously enlarged liver, weighing eleven pounds. The gall-bladder
which was very much contracted and nearly empty, contained eight calculi
and forty-seven specimens of the _Distoma lanceolatum_, all of which
were sexually mature.”
As I have remarked in a former comment on this singular case, one can
have no difficulty in arriving at the conclusion that these parasites
were obtained from the girl’s swallowing trematode larvæ, either in
their free or in their encysted condition. Leuckart says it was not
possible to ascertain whether the parasites had any connection with the
gall-stones, or whether the two maladies, so to speak, were independent
of each other; yet this question might possibly have been solved if the
calculi had been broken up in order to ascertain their structure. It
is just possible that dead distomes may have formed their nuclei, and
if so, the circumstance would, of course, point to the worms as the
original source of the malady.
So far as I am aware, the actual transformations undergone by the
larvæ of _Distoma lanceolatum_ have not been observed. The _Planorbis
marginatus_ has been confidently referred to as the intermediate bearer
of the cercariæ of the common fluke, and Leuckart supposes that the same
mollusk harbours the larvæ of this species. The ciliated embryos carry
a boring spine or tooth, and it is most probable that the higher larvæ
are similarly armed.
BIBLIOGRAPHY (No. 4).--_Kichner_ (see _Leuckart_), quoted
above.--_Cobbold_, ‘Entozoa’ (p. 187).--The case by Bucholz (reported as
one of _Fasciola hepatica_) is given by _Jördens_ in his work (quoted by
Diesing and Leuckart) ‘Entomologie und Helminthologie des menschlichen
Körpers,’ (s. 64, tab. vii, fig. 14), 1802.--_Chabert’s_ French case is
quoted by _Rudolphi_ in his ‘Entozoorum sive vermium,’ &c. (_loc. cit._,
Bibl. No. 1), p. 326, 1808.
_Distoma crassum_, Busk.--This large species was originally discovered
by Prof. Busk in the duodenum of a Lascar who died at the Seamen’s
Hospital, 1843. It, however, remained undescribed until 1859, when, with
the discoverer’s approval, I gave some account of it to the Linnean
Society.
Of the fourteen original specimens found by Mr Busk, several have been
lost. The one that he himself gave me I handed over to Prof. Leuckart,
and it is figured in his work (‘Die mensch. Par.,’ s. 586). A second
is preserved in the museum attached to the Middlesex Hospital, and a
third is contained in the Museum of the Royal College of Surgeons. This
last-named specimen is the best of the original set. It supplied me with
the few details of structure figured in outline in my ‘Introductory
Treatise’ (fig. 42, p. 123), published in 1864; and it also in part
formed the basis of the description of the species communicated to
the Linnean Society in June, 1859 (“Synopsis of the Distomidæ,” p. 5,
‘Proceedings,’ vol. v). The late Dr Lankester, it is true, was the first
to give a distinctive title to this entozoon (_Distoma Buskii_); but
as the discoverer objected to this nomenclature, and as Dr Lankester’s
proposed terms were unaccompanied by any original description, I
requested Mr Busk to suggest a new name for the worm, which he
accordingly did. As I subsequently pointed out, Von Siebold had already
employed the compound title _Distoma crassum_ to designate a small fluke
infesting the house-martin (_Hirundo urbica_); but for reasons similar
to those which contributed to set aside Dr Lankester’s nomenclature, the
title adopted in my synopsis at length came to be recognised by Leuckart
and by other well-known helminthologists. Before this recognition took
place, Dr Weinland, of Frankfort, had so far accepted Lankester’s
nomenclature as to call the species _Dicrocœlium Buskii_. In my judgment
there are no sufficient grounds for retaining Dujardin’s genus. Further,
I may observe that, in addition to the above-mentioned specimens, two
others are preserved in the Museum at King’s College. Thus, only five
out of the fourteen specimens are still in existence.
No well-authenticated second instance of the occurrence of this worm
took place until the year 1873, when a missionary and his wife from
China consulted Dr George Johnson respecting parasites from which they
were suffering. After a brief interval, both of Dr Johnson’s patients
were by an act of courtesy on the part of this eminent physician placed
under my professional care. I need hardly add that Dr Johnson had from
the very first recognised the trematode character of the parasites. From
the patients themselves I ascertained that they had been resident in
China for about four years. During that period they had together freely
partaken of fresh vegetables in the form of salad, and also occasionally
of oysters, but more particularly of fish, which, in common with the
oysters, abound in the neighbourhood of Ningpo. From their statements it
appeared to me that to one or other of these sources we must look for
an explanation of the fact of their concurrent infection. Fluke larvæ,
as we know, abound in mollusks and fish; but whether any of the forms
hitherto found in oysters or in fish have any genetic relation to the
flukes of man, is a question that cannot very well be settled in the
absence of direct experimental proof. I should add that it was not until
after their visit to the interior of the country, some 130 miles distant
from Ningpo, that the symptoms (which Dr Johnson in the first instance,
and myself subsequently, considered to have been due to the presence
of the parasites) made their appearance. Whilst in the country the
missionary and his wife freely partook of freshwater fish, and on one
occasion they received a quantity of oysters that had been sent up from
Ningpo. The husband assured me that the fish were always thoroughly well
cooked.
If it be asked what were the symptoms produced, I can only furnish
such few and hitherto unpublished particulars as the missionary
himself supplied. I need hardly say that he was a highly cultured and
intelligent gentleman, since only such persons are chosen for missionary
work in China.
From inquiries made by me on the 29th of January, 1875, I learnt
that they left Ningpo in November, 1872, and travelled thence 130
miles into the interior of the country. In the following September,
or about ten months subsequently, the missionary was attacked with
diarrhœa, which persisted until expulsion of some of the parasites had
occurred. According to the patient’s statements this result, so far,
was entirely due to his having been placed on a milk diet; this course
of treatment having been recommended by Dr Henderson, of Shanghae. The
patient himself always suspected the presence of intestinal worms of
some sort or other, although a Japanese doctor laughed at the idea of
such a thing. Some other doctor treated this missionary for parasites,
administering both male-fern and santonine without effect.
It was not until several months had elapsed that his wife was attacked
with diarrhœa. In both cases there was more or less flatus. The motions
were white, and there were other indications implying that the liver was
affected. Later on, symptoms of indigestion, with heartburn, set in and
became very severe. Streaks of blood appeared in the fæces, but there
was no dysentery. For the most part these symptoms were attributed to
the effects of climate.
When, in the month of February, 1875, I saw the missionary a second
time, professionally, I found that all the old symptoms had returned.
He had a foul tongue, the surface of the body was cold, he felt
chills, and the pulse, though regular, registered ninety-six to the
minute. Indigestion, nausea, headache, and diarrhœa had reappeared.
Notwithstanding these febrile symptoms, so satisfied was the patient
himself that all his ailments were entirely due to the presence of
parasites, that I felt inclined to take the same view of his case.
Accordingly my attention was principally directed to an effort for their
expulsion; and in this view I ordered an aloetic pill followed by a
castor-oil emulsion. This having no effect, I subsequently prescribed
aloes and assafœtida pills, followed by scammony mixture. The action
of the latter drug did not occasion griping, but, although efficient,
led only to negative results. I should mention that in the patient’s
judgment none of the vermifuges administered to him at any time had
exerted any influence in the expulsion of the flukes. He was still
thoroughly impressed with the notion that the milk diet, ordered by Dr
Henderson, was the sole cause of their expulsion.
As even a missionary could not live by milk alone I insisted upon a more
substantial diet. The milk, indeed, had occasionally been supplemented
by Liebig’s extract of meat and by light farinaceous food. When I last
saw him neither he nor his wife had passed any more flukes, but they
did not feel satisfied that no more guests remained. Somewhat improved
in general health, the missionary resolved to go back to his duties in
China. I expressed my fears, however, that his strength would prove
unequal to the work.
From the size and almost leathery texture of the two flukes which were
in the first instance submitted to my notice, I at once recognised the
species; but as they were spirit-specimens, I requested that if any more
examples were obtained they should be sent to me in the fresh state.
Fortunately others were brought in a few days, when, from an examination
conducted whilst they were still fresh, I was able to make out several
details of structure which had hitherto escaped notice. Altogether I
secured seven specimens, three of them being in a mutilated condition.
In what way these mutilations (as shown by my dried specimens) occurred
I have not been able to make out, either by personal observation or by
questioning the bearers. Two of the parasites look as though portions
had been carefully excised near the centre. The new facts I have gleaned
were derived from the examination of two comparatively small specimens,
one of which, dried, has, by Prof. Rolleston’s desire, been deposited
in the anatomical department of the University Museum at Oxford. When
I took occasion to bring some of the new specimens under Mr Busk’s
attention, he at once recognised them as referable to the species he had
long ago discovered.
The earliest literary notice of _Distoma crassum_ appeared in Dr Budd’s
classical treatise ‘On Diseases of the Liver;’ and in it the author
correctly stated, from data supplied by Mr Busk, that these human flukes
were “much thicker and larger than those of the sheep,” being, it is
added, from “an inch and a half to near three inches in length.” The
longest of my recent specimens, however, scarcely exceeds two inches,
whilst the smallest and most perfect (the one at Oxford) measures less
than an inch from head to tail. The greatest width of my broadest
specimen is little more than half an inch, or 9/16″. None of the twelve
examples that I have examined approach the length of three inches; but
Mr Busk assured me that, judging from his recollection, some of his
specimens were even longer than that. I fear, nevertheless, that the
estimate given in my Synopsis is somewhat exaggerated; at all events it
is so for average specimens.
[Illustration: FIG. 2.--The large human fluke (_Distoma crassum_) _a_,
Oral sucker; _b_, intestine; _c_, cæcal end of same; _d_, reproductive
papilla; _e_, uterine rosette (the folds of which are not branched);
_f_, one of the folds (in profile); _g_, vitellarium; _h_, hernial
protrusion (the result of an injury to the specimen); _i_, upper testis;
_j_, streaks or layers of seminal fluid which have escaped by rupture
and assumed a branched appearance; _k_, lower testis uninjured (but
slightly altered in outline from flattening); _l_, ventral sucker.
Magnified 2 diameters. Original.]
The new anatomical facts made out by me bear reference principally to
the reproductive apparatus. What else I have observed is for the most
part confirmatory of the statements made by Mr Busk. In particular,
his brief account of the position and character of the digestive
organs was not only confirmed by my earlier examinations, but is now
re-verified. In the representation given in my ‘Introduction’ I showed
in dotted outline two large organs which I supposed to be the testes.
I distinctly observed radiating lines proceeding from the centre in
each; but I could not discover the slightest trace of any limiting
border to either organ. I now found in the same position two nearly
circular flattened masses with clearly defined limits (_i_, _k_). No
doubt could be entertained as to the testicular character of the lower
organ (_k_). In the original drawing I further indicated the presence
of a third and much smaller globular mass, which I termed the ovary;
but what I supposed to represent this organ in the particular specimen
from which the accompanying illustration was drawn turns out to be
merely a hernial protrusion resulting from injury (_h_). The radiating,
broad, and branching seminal ducts are beautifully distinct in one of
my specimens, forming the most attractive feature of the parasite’s
organisation (_k_). In consequence of injury to the specimen which is
here drawn, the upper testis (_i_) displays no seminal tubes. I made out
the female reproductive organs with more completeness. In the outline
drawing given in my introductory treatise I had indicated the probable
position of the uterine folds; reducing the organ to the simplest
expression of what I concluded must obtain in the normal condition. My
conjecture was perfectly correct. The uterus consists of irregularly
folded tubes, which, though here and there apparently branching from
a central tube, are in reality folded evenly upon themselves. The
oviduct can be distinctly traced to its outlet in the reproductive
papilla, which, as usual in true Distomes, is placed in the middle line,
immediately above the ventral sucker. In my examination of Mr. Busk’s
original specimens I could not find the slightest trace of vitelligene
organs; but in my fresh examples I not only obtained proof that these
organs were largely developed, but that their limitations could be fixed
with accuracy (_g g_). They consisted of two large elongated masses, one
on either side of the body, occupying about two thirds of the entire
length of the parasite. Their yolk-vesicles were distinctly seen; but
the main efferent canals were only here and there traceable. Clearly,
the position and character of the yolk-forming glands of this large
human fluke are quite unlike those of any of its congeners. This fluke
is a remarkably fine species, and, when viewed in the fresh state with
a powerful pocket-lens, presents a most striking appearance. I did not
observe any cutaneous spines. I found the eggs to present an average
long diameter of about 1/200″, by 1/330″ in breadth. They are therefore
somewhat smaller than those of the common fluke. In the specimen
preserved in the Hunterian Museum there was complete evidence of the
presence of an excretory outlet at the caudal extremity; but I did not
succeed in finding any trace of the water-vascular system higher up. I
have no doubt, however, that it exists.
As regards the affinities of _Distoma crassum_, it is clear that this
Trematode has little in common either with the liver-fluke of cattle
and sheep (_Fasciola hepatica_), or the still larger species obtained
by me from the giraffe (_Fasciola gigantea_). The simple character
of the digestive tubes obviously connects it more closely with the
lancet-shaped fluke (_Distoma lanceolatum_), the last-named parasite
being, as already shown, an occasional resident in the human liver,
where its presence, moreover, undoubtedly contributed towards the
production of the fatal result.
In my remarks on the missionary’s diet it is hinted that the Ningpo
oysters may have played the _rôle_ of intermediary bearers to the
parasite in question; and as tending in some measure to strengthen this
notion, it should be borne in mind that Mr. Busk’s original fluke-bearer
came from the east. It is not improbable that the Lascar host may have
partaken of the same particular species of fish or shell-fish that the
missionary and his wife partook of. Be that as it may, the frequency
of the occurrence of Trematodes and their larvæ in marine mollusks is
well known. According to Woodward, several species of oyster are sold
in the Indian and Chinese markets. Thus, it would require the skill of
a malacologist to determine the particular species of _Ostrea_ to which
the Ningpo oysters should be referred.
Mons. Giard is of opinion that the singular larvæ known as _Bucephali_
attain sexual maturity in sharks and dog-fishes; therefore it is
extremely unlikely that the _Bucephali_ should have been in any way
concerned in the infection of our missionary and his wife; nevertheless
there remains the probability that these human bearers swallowed
other kinds of Trematode larvæ when they consumed the Ningpo oysters.
Moreover, if it should happen that none of the other larvæ occurring in
oysters are capable of developing into flukes in the human territory,
it yet remains highly probable that some one or other of the various
encysted (and therefore sexually immature) Trematodes known to infest
marine fishes will turn out to be the representative of our _Distoma
crassum_. In this connection we must not forget that the flesh of
the _Salmonidæ_ forms the probable source of human _Bothriocephali_;
and there is some likelihood that salt-water fishes, if not actually
the primary, may become (after the manner explained by M. Giard) the
secondary intermediary bearers of fluke-larvæ. At all events, I am
inclined to look to the Ningpo oysters, or to some other of the various
species of marine shell-fish sold in eastern markets, as the direct
source of _Distoma crassum_; for, in addition to the bucephaloid
cercarians, we have abundant evidence of the existence of other and more
highly developed fluke-larvæ in marine bivalve mollusks.
In this connection I will only further observe that we possess very
little knowledge of the parasites which take up their abode in the
viscera of savages. This ignorance results partly from the fact that
these untutored races, as proved by the statements of Kaschin and
others, actually, in the matter of severe symptoms, suffer much less
from the presence of intestinal worms than their civilised fellow-men
do. The subject is worthy of further attention, but no one, so far as I
am aware, has cared to institute the necessary inquiries in a methodical
way. I strongly suspect that several of the human parasites which we
now consider to be rare would be found to be abundant if by means of
post-mortem examinations and other methods of investigation we could
be made acquainted with the facts of helminthism as they occur amongst
the raw-flesh and fish-eating savage tribes. Of course any person,
notwithstanding the utmost care and cleanliness, as in the cases before
us, may contract a noxious parasite; nevertheless, speaking generally,
it may be said that the measure of internal parasitism affecting any
given class of people bears a strict relation to the degree of barbarism
shown by such persons in their choice of food and drink, and in their
manner of eating and drinking. This statement, if true, is not destitute
of sanitary importance; moreover, it applies not alone to ourselves, but
also to all the domesticated animals that serve our wants. Cleanliness
is just as necessary for their welfare as for our own.
In the spring of 1878 my patients returned from China. They had
experienced fresh attacks from the parasite; moreover, one of their
children, a little girl, was also victimised by the same species
of fluke. Thus, in one family I have encountered three cases of
fluke-helminthiasis due to _Distoma crassum_! One of the worms passed by
the little girl _per anum_ is now in my possession. It not only shows
the upper testis perfectly, but also the many times transversely folded,
simple, uterine rosette which is certainly not branched. There are also
traces of an organ which I take to be the cirrhus-pouch; but I have
never seen the penis protruded externally.
For the purposes of diagnosis I subjoin the following characters. The
_Distoma crassum_ is a large, flat helminth varying from an inch and a
half to two and a half inches in length, and having an average breadth
of five eighths of an inch; it is especially also characterised by its
uniform and considerable thickness, combined with the presence of a
double alimentary canal which is not branched; the body is pointed in
front, and obtusely rounded posteriorly; the integument being smooth
and unarmed; the reproductive orifices placed immediately above the
ventral sucker; the testes form two large rounded organs, situated below
the uterine rosette, and disposed in the middle line, one in front of
the other; the uterine folds occupy the front part of the body; near the
lateral margins there are two large vitelligene glands, one on either
side of the intestinal tube; the excretory organ probably consists of a
central trunk with diverging branches, opening below.
BIBLIOGRAPHY (No. 5).--_Budd_, original notice in his ‘Diseases
of the Liver,’ 2nd edition, quoted by Lankester in Appendix B to
Küchenmeister’s ‘Manual of Parasites,’ p. 437, 1857.--_Cobbold, T. S._,
“Synopsis of the _Distomidæ_,” in ‘Journ. of the Proceed. of the Linnean
Soc.,’ vol. v, Zool. Div., 1860 (original description p. 5).--_Idem_,
‘Entozoa,’ p. 193, 1864.--_Idem_, “Remarks on the Human Fluke Fauna,
with especial reference to recent additions from India and the East,”
the ‘Veterinarian,’ April, 1876.--_Idem_, “On the supposed Rarity,
Nomenclature, Structure, Affinities, and Source of the large Human Fluke
(_D. crassum_),” ‘Linn. Soc. Journ.,’ vol. xii, Zool. Div., 1876, p. 285
_et seq._--_Idem_, “Observations on the large Human Fluke, with notes
of two cases in which a missionary and his wife were the victims,” the
‘Veterinarian,’ Feb., 1876.--_Idem_, “The new Human Fluke,” in a letter
published in the ‘Lancet,’ Sept., 1875.--_Leidy_, in ‘Proceed. Acad.
Nat. Sciences of Philadelphia;’ see also Dr McConnell’s paper quoted
below (Bibl. No. 6).--_Leuckart_, l. c., Bd. I, s. 560.--_Weinland_, l.
c. (Bibl. No. 2), Appendix, p. 87.
_Distoma Sinense_, Cobbold.--The discovery of this species is due to
Prof. J. F. P. McConnell, who “on the 9th of Sept., 1874, found a large
number of flukes in the liver of a Chinese, obstructing the bile ducts.”
The species measures 7/10″ in length, by 1/7″ in breadth, the eggs
being 1/833″ by 1/1666″. Dr McConnell showed in his original memoir
that the worm cannot well be confounded with _Fasciola hepatica_, with
_Distoma lanceolatum_, or with _D. conjunctum_. In this conclusion he
was supported by Dr T. R. Lewis, who examined the specimens with him.
In a letter communicated to the ‘Lancet,’ quoted above, I proposed
the nomenclature here given; but Prof. Leuckart, unaware of this
step, afterwards suggested the terms _Distomum spatulatum_. Later on
I received numerous specimens from Calcutta, the examination of which
enabled me to confirm the accuracy of the original description. As
regards the male organs in the subjoined figure, it will be seen, by
comparing the lettering and references, that I have interpreted the
facts of structure somewhat differently from Prof. McConnell.
[Illustration: FIG. 3.--The Chinese fluke (_Distoma Sinense_). _a_, Oral
sucker; _b_, œsophageal bulb; _c_, intestine; _c′_, cæcal end; _d_,
ventral sucker; _e_, genital pore; _f_, uterine folds; _g_, ovary; _h_,
vitellarium; _i_, vitelligene duct; _k_, upper seminal reservoir; _l_,
testes; _m_, lower seminal pouch; _o_, vas deferens; _p_, pulsatile
vesicle; _p′_, water vessel. After McConnell.]
In the month of December, 1874, a Chinese died in the Civil Hospital
at Port Louis, Mauritius, whilst he was under the care of Dr William
Macgregor, chief medical officer of the Colony of Fiji. The post
mortem revealed the presence of a very great number of flukes in the
bile-ducts. Dr Macgregor described these parasites with great care, and
having favored me with a copy of his manuscript I at once recognised the
worms to be identical with the species discovered by McConnell. I also
received through Dr Henry Clark, of Glasgow, two Mauritius specimens,
which when compared with the Calcutta examples proved to be specifically
identical. Dr Macgregor’s paper, communicated to the Glasgow
Medico-Chirurgical Society, gives full particulars of the helminthiasis
associated with this parasite, whilst both his and Prof. McConnell’s
account of the structure of the worm are remarkably complete in details,
and well illustrated. It is not a little curious to notice that although
these parasites were obtained in countries far removed from China, they
were in both instances taken from Chinese; moreover, from the statements
of Macgregor, it appears very probable that the parasites in question
are a common source of liver disease. Without doubt oriental habits are
eminently favorable to fluke infection, for we are now acquainted with
four species of flukes whose geographical range is limited to eastern
parts.
BIBLIOGRAPHY (No. 6).--_McConnell, J. F. P._, “Remarks on the Anatomy
and Pathological relations of a new species of Liver-fluke,” ‘Lancet,’
Aug. 1875; repr. in the ‘Veterinarian,’ Oct., 1875; also in the
‘Lancet,’ March 16th, 1878, p. 406.--_Macgregor, W._, “A new form of
Paralytic Disease, associated with the presence of a new species of
Liver Parasite (_Distoma Sinense_),” ‘Glasgow Med. Journ.’ for Jan.,
1877; also in the ‘Lancet’ for May 26th, 1877, p. 775.--_Cobbold, T.
S._, in a note to the ‘Lancet,’ Sept., 1875, and in the Appendix to
Macgregor’s paper, p. 15, 1877.--_Leuckart, R._, l. c., Bd. ii, s. 871,
1876.
_Distoma conjunctum_, Cobbold.--The little fluke which I first
discovered in the gall-ducts of an American fox (_Canis fulvus_) was
fourteen years afterwards obtained from pariah dogs in India by Dr. T.
R. Lewis (1872); but it remained for Prof. McConnell to show that this
entozoon also invades the human subject (1874). A second instance of its
occurrence in man was recorded in 1876. We all figured the worm, and in
respect of general details our descriptions for the most part agreed
(fig. 56). The worms from the dog and fox gave an average of 1/4″ in
length, but the majority of those found by McConnell in man were fully
3/8″ from head to tail.
Writing in the spring of 1876 Dr McConnell says:--“In the ‘Lancet’ for
the 21st of August, 1875, I published the description of a new species
of liver-fluke found in the bile-ducts of a Chinaman (_sic_) who died in
this hospital. Dr Spencer Cobbold has very kindly interested himself
in this discovery, and proposed the name of _Distoma Sinense_ for the
new fluke. This discovery (in September, 1874) has stimulated me to pay
still greater attention to the morbid conditions of the biliary canals
in our post-mortem examinations; but, although more than 500 autopsies
have been conducted since that date, I have not met with another
instance of distomata in the liver until within the last fortnight. On
the 9th of January, 1876, in examining the liver of a native patient who
had died in the hospital, I again found a large number of flukes in the
bile-ducts, and having carefully examined many specimens, I recognise
the species as the _D. conjunctum_ of Cobbold. Dr Cobbold discovered
this fluke in 1858; but, as far as I am aware, the human liver has never
hitherto been found infested by these parasites, and this will give
general interest and importance to the following case.”
“Jamalli Khan, a Mahommedan, aged twenty-four, admitted into the
hospital on the 25th of December, 1875. He is a resident of Calcutta,
and an ordinary labourer (coolie). He states that he had been suffering
from ‘fever’ for the last two months, at first intermittent in
character, but for the last seven days more or less continued. He is
much emaciated and reduced in strength. Complains of pain on pressure
over the liver and spleen; the latter can be felt much enlarged,
reaching downwards to nearly the level of the umbilicus; the lower
border of the liver, however, can only just be felt below the ribs.
Temperature on evening of admission 101° F. Conjunctivæ are anæmic,
but not jaundiced. Has also a little bronchitis. The fever continued
with slight remissions for ten days (January 4th, 1876), the highest
diurnal temperature (in the afternoon) varying from 103° to 104° F.; it
then abated, but dysentery set in. He began to pass six or eight stools
in the twenty-four hours, attended with much griping, and containing
varying quantities of blood-tinged, gelatinous mucus. These became more
frequent, in spite of treatment, during the next three days, and on the
8th of January he was manifestly sinking; passed his evacuations into
the bedclothes, became cold and collapsed, and died in this state that
same evening.
“A post-mortem examination was made on the following morning, thirteen
hours after death. All the organs of the body were found more or less
anæmic, but exhibited nothing remarkable with the following exceptions.
The lungs towards their posterior margins and bases were dark, but still
spongy and crepitant. The spleen was found greatly enlarged, heavy;
capsule tense and stretched; substance soft, reddish brown, irregularly
pigmented; weight 1 lb. 13 oz. The liver was of about normal size; its
surfaces smooth, the capsule slightly hazy looking. Hepatic substance
firm, but abnormally dark, and the bile-ducts particularly prominent
and thickened. Numbers of small distomata escaped from the incisions
made into the organ, and could be seen protruding from the dilated
biliary canals. The gall-bladder was filled with thick greenish-yellow
bile, measuring about an ounce and a half, but containing no parasites,
and no ova even could be detected on microscopical examination of this
bile and of scrapings from the lining membrane of the gall-bladder.
The cystic duct was free from obstruction. The condition of the common
choledic duct could not so well be ascertained, as the liver had been
removed from the abdominal cavity before anything extraordinary had been
detected in its condition, but, so far as it could be examined, it was
found patent; the duodenal mucous membrane was well bile-stained, and
there was evidence of biliary colouring matter in the fæcal contents
of the bowels. On carefully dissecting out, and then laying open, the
biliary ducts in a portion of the right lobe of the liver (the rest
being preserved entire), numbers of distomata were found within them,
lying singly, flattened, and generally with the anterior extremity,
or “oral sucker,” directed towards the periphery of the organ, the
posterior extremity towards its centre; or in twos, threes, or even
little groups of fours, variously coiled upon themselves or upon each
other. The lining membrane of the biliary canals was found abnormally
vascular, its epithelial contents abundant (catarrh?), and, among these,
ova could be detected under the microscope. Sections of the liver,
hardened and then examined in glycerine, showed fatty infiltration of
the lobular structure, but not to any advanced degree; the bile ducts
considerably dilated, their walls thick and hypertrophied, but nothing
else abnormal, or in any way remarkable. The weight of the liver was 3
lbs. In the transverse and descending colon numerous indolent-looking,
shallow, pigmented ulcers were found, and in the rectum others evidently
more recent and highly injected. The submucous tissues throughout were
abnormally thickened. The intestinal contents consisted of only about
three ounces of thin yellowish (bilious) fæcal fluid, with small bits of
opaque mucus. This was carefully washed and examined, but no flukes were
discovered. About a dozen distomata escaped from the liver on making the
primary incisions, and quite twice this number was found subsequently
within the biliary canals. Only a portion of the right lobe has, as I
have said, been dissected, so that it may be confidently stated that
probably not less than a hundred of these flukes must have infested
this liver. All were found dead, but it must be remembered that the
autopsy was performed thirteen hours after the death of the patient.
It is remarkable that in this case, as in the one before described by
me, no distomata were found in the gall-bladder. The presence of these
parasites in the bile-ducts seems to have led to catarrhal inflammation
of their lining membrane and abnormal thickening and dilatation of
their walls, but there is no evidence of their having caused sufficient
obstruction to produce cholæmia, as in the case just referred to, and no
marked pathological change could be detected in the lobular structure of
the liver.”
After referring to the anatomical descriptions of the worm, as recorded
by myself (in ‘Entozoa’) and by Lewis (in the memoir quoted below),
Professor McConnell further observes that the addition of a few more
particulars seems necessary for the determination of the identity of the
species. He then gives the following characters:
“Body lanceolate, anterior and posterior extremities pointed, the latter
obtusely. Surface covered with minute spines or hairs. Average length
3/8″ (three eighths of an inch); average breadth 1/10″. ‘Ventral’ sucker
slightly smaller than ‘oral.’ Reproductive papilla or genital orifice
placed a little above and to one side of the former. Alimentary canal
double and unbranched. Uterine folds and ovary placed in the median
line, and above the male generative organs, the latter consisting of two
very distinct globular bodies or testes. Ova of the usual type, _i. e._
oval in outline, having a double contour, and granular contents; average
length, 1/750″; average breadth, 1/1333″. The only point of note is that
the average length of these flukes is greater than that of the same
species found by the authors above referred to. The _D. conjunctum_ in
the American fox, and in the pariah dog, has an average length of 1/4″;
only two or three specimens of this size were found in this liver, and
these showed evidences of immaturity; a few were found 1/2″ in length;
but the great majority exactly 3/8″. The anatomical characters are
otherwise precisely identical.”
Professor McConnell concludes his communication by a remark in reference
to the common source of infection shared by mankind and dogs in India.
The occurrence, however, of this entozoon in an American red fox points
to a very wide geographical distribution of the species. It is hardly
likely that the fox, though dying in the London Zoological Society’s
Menagerie, should have contracted the parasite in England. In the second
half of this work I shall reproduce my original drawing (fig. 56) from
the ‘Linnean Transactions;’ but I may refer to my Manual (quoted below)
for a reproduction of McConnell’s figure. In my original specimens the
integumentary spines had fallen, probably as a result of post-mortem
decomposition.
BIBLIOGRAPHY (No. 7).--_Cobbold, T. S._, “Synopsis of the Distomidæ” (l.
c.), 1859; and in “Further Observations on Entozoa, with experiments,”
‘Linn. Trans.,’ vol. xxiii (tab. 33, p. 349), 1860.--_Idem_, “List
of Entozoa, including Pentastomes, from animals dying at the Zool.
Soc. Menagerie between the years 1857-60,” ‘Proceed. Zool. Soc.,’
1861.--_Idem_, ‘Entozoa,’ p. 20, pl. ii, 1864; and in “Manual
of the Internal Parasites of our Domesticated Animals,” p. 81,
1873.--_Lewis, T. R._, and _Cunningham, D. D._, in a footnote to their
‘Microscopical and Physiological Researches,’ Appendix C., ‘Eighth Ann.
Rep. of the San. Comm. with the Govt. of India,’ p. 168, Calcutta,
1872.--_McConnell, J. F. P._, “On the _Distoma conjunctum_,” in the
‘Lancet’ for 1875-76, quoted above; reprinted in the ‘Veterinarian,’
1876; also (a second case) in the ‘Lancet’ for March 30th, 1878, p. 476.
_Distoma heterophyes_, Von Siebold.--This minute parasite, measuring
only 3/4 of a line in length, was discovered by Dr Bilharz, of Cairo,
in the intestines of a lad, post-mortem, in the year 1851. A second
similar instance occurred, when several hundred examples were collected
and afterwards distributed amongst the helminthologists of Europe.
Through the kindness of Leuckart two of the worms eventually reached
myself. From one of these the accompanying figure was drawn. For the
purpose of supplying a full diagnosis I have elsewhere described this
worm as presenting an oblong, pyriform outline, attenuated in front, and
obtusely rounded behind; body compressed throughout, the surface being
armed with numerous minute spines, which are particularly conspicuous
(under the microscope) towards the head; oral and ventral suckers
largely developed, the latter being near the centre of the body, and
about twice the diameter of the former; pharyngeal bulb distinct and
separate from the oral sucker, and continued into a long œsophagus,
which divides immediately above the ventral acetabulum; intestinal tubes
simple, gradually widening below and terminating near the posterior
end of the body; reproductive orifices inconspicuous, but evidently
placed below and a little to the right of the ventral sucker, at which
point they are surrounded by a special accessory organ, resembling a
supernumerary sucker; uterine folds numerous and communicating with
small but conspicuously developed vitelligene glands; testes spherical
and placed on the same level in the lower part of the body; ovary
distinct; aquiferous system terminating inferiorly in a large oval
contractile vesicle, the latter opening externally by a central _foramen
caudale_.
Apart from its minuteness, moreover, this trematode is especially
characterised by the possession of a very remarkable apparatus
surrounding the reproductive orifices. It consists of an irregularly
circular disk, measuring 1/125″ in diameter, and having a thick-lipped
margin, which supports seventy fish-basket-like horny ribs comparable
to the claw-formations seen in the genus _Octobothrium_. According to
Bilharz these ribs give off five little branches from their sides, but
Leuckart could not see them in his specimens. Leuckart estimated the
length of these horny filaments to be 1/1250″, whilst their breadth was
1/3570″. On the whole we may regard this organ as a complicated form of
“holdfast” designed to facilitate or give efficiency to the sexual act.
I may here also state that this structure is by no means unique; for,
if I mistake not, it exists in an equally developed degree in the young
trematode which Dr Leared found infesting the heart of a turtle. Leared
believed that he had found an ordinary distome; an opinion to which I
could not give my assent, seeing that the organ described by him as a
“folded, ventral sucker” presented a very different aspect to the oral
sucker displayed by the same animal. Without doubt, however, the organ
in his so-called _Distoma constrictum_ is analogous to the supplementary
“holdfast” existing in _Distoma heterophyes_. The views which I
originally advanced as to the source and condition of the parasite are
probably correct.
[Illustration: FIG. 4.--The small Egyptian fluke (_Distoma
heterophyes_), viewed from behind. The large ventral sucker,
supplementary disk, uterus, testes, simple divided intestine,
vitellarium, and pulsatile vesicle are conspicuous. Original.]
As regards the structure of _Distoma heterophyes_, I have only to add
that a special set of glandular organs is situated on either side of the
elongated œsophagus, but the connection between these organs and the
digestive apparatus has not been clearly made out. Leuckart compares
them to the so-called salivary glands found in _Distoma lanceolatum_,
and says, “The presence of such a glandular apparatus is also indicated
by the more ventral position of the oral sucker, and the development of
the cephalic margin.” The conspicuous contractile vesicle terminating
the excretory system is developed to an unusually large extent,
exhibiting in its interior multitudes of the well-known active molecular
particles. Lastly, I have only to add that the eggs of _Distoma
heterophyes_ measure 1/990″ in length by 1/666″ transversely.
BIBLIOGRAPHY (No. 8).--_Bilharz_, “Beitrag zur Helminth. humana,”
‘Zeitsch. für wissenschaftl. Zool.,’ s. 62, 1851.--_Cobbold_,
‘Entozoa,’ p. 195, 1864.--_Küchenmeister, F._, ‘Parasiten,’ 1855, s.
210, Eng. edit., p. 276, 1857.--_Leared_, “Description of _Distoma
constrictum_,” ‘Quarterly Journal of Micros. Science,’ new series, vol.
ii, 1862.--_Leuckart, R._, l. c., s. 613, 1863.--_Moquin-Tandon_, on the
Genus _Fasciola_, l. c., 1861.--_Weinland_, on _Dicrocœlium_, l. c., p.
86, 1858.
_Distoma ophthalmobium_, Diesing.--There is every reason to believe
that the small flukes found by Gescheid and Von Ammon in the human eye
were sexually immature worms, but since it cannot be decided as to what
adult species they are referable I prefer to notice them under the usual
title. Possibly these eye-worms may be referred to _D. lanceolatum_, as
suggested by Leuckart. However that may be, I deem it unnecessary to
repeat the details recorded in the treatises quoted below. The largest
examples measured only half a line or about one millimètre in length.
[Illustration: FIG. 5.--The eye fluke (_Distoma ophthalmobium_). Showing
the suckers and intestinal tubes. After Von Ammon.]
BIBLIOGRAPHY (No. 9).--_Cobbold_, ‘Entozoa,’ p. 191.--_Gescheid (D.
oculi humani)_, in Von Ammon’s ‘Zeitsch. f. Ophth.,’ iii, and also
in Ammon’s ‘Klin. Darstell. d. Krankheit d. Menschl. Auges.,’ vols.
i and iii.--_Küchenmeister_, Eng. edit., p. 287.--_Leuckart_, l. c.,
s. 610.--_Nordmann (Monostoma lentis)_, “Mikr. Beitr.,” Heft. ii,
‘Vorwort,’ s. ix, 1832.
_Tetrastoma renale_, Chiaje; _Hexathyridium pinguicola_, Treutler;
and _H. venarum_, Treutler.--Whether these forms are good species or
not, the fact that they were genuine parasites cannot, I think, be
disputed. The first-mentioned measured five lines in length, and was
found by Lucarelli in the urine. The second, eight lines long, was found
by Treutler in a small tumour connected with the ovary. The third,
measuring three lines in length, was twice found in venous blood, and
twice in the sputum of patients suffering from hæmoptysis.
BIBLIOGRAPHY (No. 10).--_Delle-Chiaje_, ‘Elmintografia Umana,’
1833.--_Bremser_ (l. c., Bibl. No. 2), s. 265, 1819.--_Cobbold_,
‘Entozoa’ (p. 204, et seq.).--_Dujardin_ (l. c., Bibl. No. 2), s. 265,
1819.--_Treutler_, ‘Obs. Path. Anat. ad Helm. Corp. Humani,’ p. 19,
1793.--_Zeder_, ‘Anleitung zur Naturg. der Eingeweidewürmer,’ s. 230,
1803.
_Amphistoma hominis_, Lewis, and McConnell.--The original account of
this species is based upon two finds. The first series of specimens was
procured from Dr J. O’Brien, of Gowhatty, and the second set from the
Pathological Museum of the Calcutta Medical College. Dr O’Brien and Dr
Curran together procured their specimens, post-mortem, from an Assamese.
There were hundreds of worms present in the vicinity of the ileo-colic
valve. The museum specimens were procured from a patient who died at the
Tirhoot gaol hospital in 1857. They were (say the authors) presented to
the museum by Dr Simpson, and in the catalogue their history was briefly
recorded as follows:
[Illustration: FIG. 6.--The human amphistome (_Amphistoma hominis_).
Longitudinal section. _a_, Oral sucker; _b_, pharyngeal bulb; _c_, nerve
ganglia; _d_, œsophagus; _e_, genital pore; _f_, vagina; _g_, ductus
ejaculatorius; _h_, ventral nerve cords; _i_, intestinal canal; _j_,
upper testis; _k_, water vessel; _l_, lower testis (ovary according
to Lewis); _m_, principal ducts of the vitellarium; _n_, branches of
the vitellary ducts; _o_, ventral pouch or bursa; _p_, caudal sucker.
Magnified 12 diameters. After Lewis.]
“The cæcum of a native prisoner who died from cholera in the Tirhoot
gaol hospital, with a number of peculiar and, probably, hitherto
unrecognised parasites, found alive in that part of the intestinal
canal.” (_Presented by Dr Simpson through Professor E. Goodeve._)
In continuation of their narrative, Drs Lewis and McConnell go on to
say that, “with reference to this preparation, the following very
interesting particulars from the ‘Annual Jail Report of Tirhoot’
for 1857 have been very kindly placed at our disposal by the
Surgeon-General, Indian Medical Department. The prisoner, Singhesur
Doradh, aged 30, was attacked with cholera on the 13th, and died on
the 14th of July, 1857. Had not been in hospital previously, and was
employed in cleaning the jail.”
The post-mortem examination was made three hours after death:--“Colon
externally livid, contracted; contains a little serous fluid with
flakes of mucus. Mucous membrane healthy except venous injection. In
the cæcum and ascending colon numerous parasites like tadpoles, alive,
adhering to the mucous membrane by their mouths. The mucous membrane
marked with numerous red spots like leech-bites from these parasites.
The parasites found only in the cæcum and ascending colon, none in the
small intestines.” This description is by Dr Simpson, who adds, “I
have never seen such parasites, and apparently they are unknown to the
natives. They are of a red colour, size of a tadpole, some young, others
apparently full grown, alive, adhering to mucous membrane,--head round,
with circular open mouth, which they had the power of dilating and
contracting. Body short and tapering to a blunt point.”
Drs Lewis and McConnell’s description of the worm is too long to be
quoted in full. The parasites measure 1/5″ to 1/3″ in length, by 1/8″ to
1/6″ in breadth. Science is much indebted to these eminent observers for
having unearthed the museum specimens and for recording the facts they
could gather. From a zoological point of view the most interesting fact
connected with Lewis’s amphistome is the existence of a gastric pouch.
This structure brings these human _Masuri_ into close relation with the
equine parasite which I have named _Gastrodiscus Sonsinoii_, and which
will be found illustrated in this work (fig. 62). In short, Lewis’s worm
appears like a transition form; the absence of gastric supplementary
suckerlets separating it from the new generic type.
BIBLIOGRAPHY (No. 11).--_Lewis, T. R., and McConnell, T. F. P.,_ “_Amph.
hominis_; a new parasite affecting Man,” ‘Proceedings of the Asiatic
Society of Bengal,’ Aug., 1876.
_Bilharzia hæmatobia_, Cobbold.--This remarkable parasite was discovered
by Bilharz in 1851. It was subsequently found by myself in an ape
(1857); other species of the same genus having since been detected by
Sonsino in the ox and sheep (1876). The human examples were originally
obtained from the portal system of blood-vessels. Afterwards they were
obtained by Bilharz, Griesinger, and others, from the veins of the
mesentery and bladder. It was shown that they were not only associated
with, but actually gave rise to a formidable and very common disease in
Egypt.
In 1864 Dr John Harley made the interesting announcement that he had
discovered specimens of this singular genus in a patient from the
Cape of Good Hope. He also showed that the entozoon was the cause
of the _hæmaturia_ known to be endemic at the Cape. Harley believed
his parasites to represent a new species (_Distoma capense_), but in
this view I showed that he was mistaken. His admirable contribution,
nevertheless, served not only to establish the wide range of this
parasite on the African continent, but also to throw much light upon
the subject of endemic helminthiasis. As this worm forms an almost
altogether exceptional type of fluke-structure, it became necessary
to supersede the original nomenclature proposed by Bilharz and Von
Siebold (_Distoma hæmatobium_). Accordingly I proposed the term
_Bilharzia_, whilst other helminthologists subsequently proposed various
titles (_Gynæcophorus_, Diesing; _Schistosoma_, Weinland; _Thecosoma_,
Moquin-Tandon). On various grounds, and chiefly on account of priority,
most writers have at length definitely accepted the nomenclature which
employed the discoverer’s name for generic recognition.
[Illustration: FIG. 7.--The blood fluke (_Bilharzia hæmatobia_). The
lower end of the female is withdrawn from the gynæcophoric canal of the
male. After Küchenmeister.]
The _Bilharzia hæmatobia_ may be described as a trematode helminth
in which the male and female reproductive organs occur in separate
individuals; the male being a cylindrical vermiform worm, measuring only
half an inch or rather more in length, whilst the female is filiform,
longer, and much narrower than the male, being about four fifths of
an inch from head to tail; in both, the oral and ventral suckers are
placed near each other at the front of the body; in the male the suckers
measuring 1/100″, in the female 1/314″ in diameter; in either, the
reproductive orifice occurs immediately below the ventral acetabulum.
The comparatively short, thick, and flattened body of the male is
tuberculated and furnished with a _gynæcophoric_ canal, extending from
a point a little below the ventral sucker to the extremity of the tail;
this slit-like cavity being formed by the narrowing and bending inwards
of the lateral borders of the animal, the right side being more or less
completely overlapped by the left margin of the body; caudal extremity
pointed; intestine in the form of two simple blind canals. Female with a
cylindrical body measuring only 1/312″ of an inch in thickness in front
of the oral sucker; lodged in the gynæcophoric canal of the male during
the copulatory act; thickness of the body below the ventral acetabulum
being about 1/357″, and at the lower part 1/96″; surface almost smooth
throughout; intestinal canals reunited after a short separation to form
a broad, central, spirally twisted tube extending down the middle of
the body; vitelligene and germigene canals combining to form a simple
oviducal canal, which is continued into a simple uterine tube, finally
opening near the lower margin of the ventral sucker; eggs pointed at one
end, or furnished with a projecting spine near the hinder pole.
The study of the structure and formation of the contents of the ova
possesses great interest. When fully developed the eggs are oval,
measuring from 1/180″ to 1/160″ in length, with an average transverse
diameter of 1/325″. Some are a trifle larger, others smaller.
Occasionally one encounters narrow specimens, and also aberrant forms
presenting a pear-shaped outline. I have met with eggs not exceeding
1/250″ in their long diameter, and 1/500″ transversely, whose
yolk-contents had already arrived at an advanced stage of segmentation.
[Illustration: FIG. 8.--Two eggs of _Bilharzia_. _a_, With the yolk
coarsely segmented; _b_, with the yolk granulated and the spine wanting.
Original.]
The shell is transparent, of a brown colour, and free from any markings,
lines, or sculpturing. One pole of the shell is invariably narrower than
the other, and usually presents a more or less pointed extremity (fig.
8). This narrow end commonly displays a sharp, projecting, beak-like
spine, which, at its base, constantly rests upon the centre of the pole
of the shell, but occasionally it is eccentrically placed (fig. 8_a_).
In some few examples the spine is removed to a little distance from the
actual extremity of the shell; but even in these instances, so far as
my observations go, its apex always projects beyond the level of the
curved end of the pole. Now and then the spine is altogether absent
(fig. 8_b_); and when present it is, as already hinted, very unequally
developed. In size the spine ranges from a mere point, having an extreme
length of only 1/8000″, up to the comparatively large magnitude of
1/2500″ lengthways.
According to the best evidence there is no good ground for asserting the
existence of any specific differentiation between the parasites coming
from the Cape and Egypt respectively.
[Illustration: FIG. 9.--Two eggs of _Bilharzia_, with eccentrically
placed spines. That to the left shows mulberry cleavage of the yolk; the
other having lost its embryonal contents by rupture. Original.]
Taking a more extended view of the significance of these singular
chorional spines, I think we may here recognise the early efforts of
Nature, so to speak, to form or evolve a special organ, which, in
the eggs of certain other parasites, becomes capable of attaining
a relatively prodigious degree of development. To me it seems that
the little process in question is a kind of rudimentary holdfast;
and, as such, it may be reckoned as the homologue of a variety of
egg-appendages. Eleven years ago Mr Edwin Canton discovered some curious
ova attached to the conjunctiva of a turtle’s eye. I had no hesitation
in pronouncing them to be referable to some ectozoon or entozoon
belonging to one or other of the allied genera _Polystoma_, _Tristoma_,
_Octobothrium_, and _Dactylogyrus_. Now, whilst the Bilharzia ova
display only a solitary and imperfectly developed holdfast, placed at
one end of the shell, the singular eggs described by Mr Canton develop
organs of anchorage at both extremities. Parasitic ova exhibiting
analogous processes, spines, and filamentary appendages at both poles,
have been observed in various species of parasite--as, for example,
in _Monostoma verrucosum_ infesting the fox, in _Tænia cyathiformis_
infesting the swallow, in _Tænia variabilis_ of the gambet, in
_Octobothrium lanceolatum_ attached to the gills of the common herring;
and in _Polystoma appendiculata_, from the branchiæ of various marine
fishes. Eggs of parasites which, like _Bilharzia_, are furnished with a
single appendage, may likewise be seen in the ova of different species
of _Dactylogyrus_ infesting the gills of the pike. In the more strongly
pronounced developments it is easy to perceive how admirably these
outgrowths are adapted to the necessities of the different species of
parasite to which they are severally referable; and, even in the case of
_Bilharzia_, the trifling amount of anchorage furnished by a projecting
point is not absolutely thrown away. The resistance will also be greater
where the spine is situated a little on one side of the pole of the egg,
which seems to need steadying during the violent struggles of the embryo
to escape from its temporary abode.
[Illustration: FIG. 10.--Free ciliated embryo of _Bilharzia_, with
pear-shaped rudimentary organs below the head. Original.]
[Illustration: FIG. 11.--Two ciliated embryos of _Bilharzia_; showing
sarcode spherules in their interior. That to the left has recently
escaped the shell. Original.]
When any number of ova are removed from the urine and examined, it
will be found that a large proportion of them contain embryos in an
advanced stage of larval growth. The structural appearances presented
by the embryos whilst still in the eggs are remarkably uniform; since,
in all, the yolk appears to have resolved itself into a mass of rounded
sarcode-globules, one or two of these particles being conspicuously
larger than the rest (fig. 12). At this stage, except towards the
cephalic division of the larva, no tendency to differentiation is
perceptible; but some time after the embryo has escaped, one may notice
elongated masses of sarcode formed by the coalescence of the globules.
Whilst still in the egg, one end of the primitive embryonal mass becomes
gradually narrowed, cilia at the same time appearing. This part becomes
the future head, eventually acquiring the form of a cowl. Whatever form
the body of the embryo may display after extrusion from the shell,
the head retains its conical shape, the cone itself being narrowed or
widened only when the larva is subjected to abnormal conditions (fig.
14). Whilst the head is undergoing development within the shell, one,
two, or sometimes three, pyriform masses make their appearance within
the cone; and after the embryo has escaped, these structures become more
marked (fig. 10). The sarcode-globules refract light strongly; and, when
the larva is not compressed in any way, they move freely within the
somatic cavity. In well-developed embryos, whilst still in the egg, the
cilia are observed to clothe every part of the larva except the oral
papilla. This minute nipple-like projection measures about the 1/3000 of
an inch transversely, forming a very simple kind of unarmed proboscis.
When the head of the free embryo is viewed from above, the proboscis
looks like a central ring surrounded by a series of regular folds, which
radiate outwards like the spokes of a wheel. The ridges thus formed
support numerous cilia, these latter projecting at the circumferential
margin of the cephalic cone in such a way as to present the figure of
a star. Dr Harley has admirably represented this character, which is
shared by many other parasitic larvæ. Throughout the greater part of
the time, whilst the embryo is still resident within the egg, the broad
neck or base of the cephalic cone forms a fixed point of resistance by
its firm attachment to the inner wall of the shell; and this structural
union, so long as it remains intact, enables the embryo to move not
only its head and body from side to side synchronously, but also each
part independently. When the time for final escape is drawing near,
the vigorous movements of the cone-shaped head seem chiefly concerned
in loosening the membranous connection just referred to; and when, at
length, the ciliated animalcule has succeeded in overcoming this first
difficulty, it is ludicrous to witness its frantic efforts to find an
opening in the shell. While thus partially liberated, it will rush to
and fro from one pole of the egg to the other, performing a series of
summersaults, and at the same time occasionally rolling itself over
laterally. This activity becomes gradually more and more violent, until
at length its excitement is worked up into a sort of frenzy. I have
many times watched these performances, which, however, are only to be
seen within those ova whose shells, for some reason or other, refuse to
yield to the earlier and ordinary efforts of the prisoner. In all cases
where these phenomena are witnessed the eye readily detects a number of
small free globules between the embryo and the inner wall of the shell
(fig. 13). These minute particles are likewise tossed about tumultuously
during the rapid rotatory movements of the imprisoned larva. Except
as regards their size, these globules do not differ in character from
the sarcodic contents of the animalcule. They are probably superfluous
detachments from the primitive yolk-mass, but it is possible that they
may afford some aid in the final breaking up of the shell. Whilst the
embryo remains fixed its tail is usually directed towards the narrower
or spine-bearing pole of the egg, but in a few instances I have seen
this position reversed. As regards the precise mode of emerging from the
shell, and the time occupied by the larva in freeing itself, there are
several points of interest. Speaking generally, the purer the medium
into which the ova are transferred, the more rapid will be the movements
of the larvæ. To give an example of observed facts in relation to the
rapidity of development, I cite the following:--“On the 20th of August,
1870, I placed twelve eggs of _Bilharzia_ under the microscope. The
medium in which they were immersed consisted of eight parts of ordinary
drinking water to one of urine. At the expiration of seventeen minutes
the first-born made its escape. In the course of another minute two more
emerged. In twenty-six minutes the fourth, in twenty-eight the fifth, in
thirty-two the sixth, in thirty-four the seventh, in thirty-seven the
eighth, in thirty-eight the ninth, in forty the tenth, in forty-three
the eleventh, and in forty-six minutes the twelfth, respectively made
their appearance.”
[Illustration: FIG. 12.--Egg of _Bilharzia_, with contained embryo and
free sarcode globules. Original.]
[Illustration: FIG. 13.--Free ciliated embryo of _Bilharzia_, slightly
deformed, and having the pear-shaped organs largely developed. Original.]
[Illustration: FIG. 14.--Ciliated embryos of _Bilharzia_, deformed by
the application of reagents. Original.]
Now, this rapid mode of birth and emergence from the shell is very much
more striking in the case of eggs which are placed in perfectly pure
water; for, whilst the eggs are still in the urine, there appears to
be neither the power nor the inclination on the part of the embryo to
escape; but, on isolating and placing them in suitable conditions, their
behaviour is even more remarkable. In a space of less than two minutes
I have repeatedly seen the hitherto motionless embryo alter its shape
by contractions, become violently agitated, and burst out of its shell
in the condition of a free-swimming animalcule. Moreover, it is worthy
of remark that the eggs and larvæ of _Bilharzia_ soon perish in stale
urine. “On the 16th of August, 1870, I placed about a thousand eggs
in a quart of fountain-water, to which only a drachm or rather less
of urine had been added. At the expiration of forty-eight hours not a
single living embryo could be found. I subsequently ascertained that I
could not keep the embryos alive for twenty-four hours in any water in
which I had introduced the smallest trace of mucus, blood-corpuscles,
urinary crystals, or decomposing matters of any kind. All sorts of
reagents speedily killed the larvæ. Mere discoloration by carmine
solution, or by the addition of a drop of the solution of permanganate
of potash, instantly caused them to assume grotesque and unnatural
shapes (figs. 13 and 14), death sooner or later following as a result
of the disintegration and resolution of their delicate bodies into mere
sarcode-masses. Still more rapidly poisonous effects were produced by
the addition of a little sherry or alcohol. In solutions where the
amount of spirit did not exceed one part of spirit, proof strength, to
fifty parts of water the effect was the same.”
The development of the larva is equally well accomplished in distilled
water, in well-water, and in brackish water. In pure sea-water the
process goes on less satisfactorily. It was found, indeed, that the
addition of slightly saline water to ciliated embryos, which were on the
point of expiring in fresh water, had the effect of reviving them for a
time. These facts have an important practical bearing.
I have thus shown that the escape of the embryo is by no means the slow
process that Bilharz has described. Almost invariably the shell bursts
by a longitudinal slit extending over fully two thirds of its long
diameter, the first point of rupture being commonly situated midway
between the spine and the centre of the shell. In normal births, so
to speak, the head of the animalcule emerges first; but occasionally
the animal escapes sideways, and I have even seen the embryo extricate
itself tail foremost. Not unfrequently it has a difficulty in detaching
itself from the shell, in which case the egg is whirled round and
round by the half-freed prisoner (fig. 15). The lodgment of the spine,
however, against any foreign substance affords the necessary leverage
for ensuring escape.
The larva never displays its proper elongated, spindle-shaped, or
cylindro-conical figure, until some short time after its escape from the
shell; and, as a consequence of this, its powers of locomotion are less
marked at first than they are subsequently. At the time of extrusion
the larvæ are commonly more or less hour-glass shaped (fig. 11); this
particular form being sometimes retained for many minutes or even for
an hour. Usually the larvæ have a tendency to acquire their normal
shape immediately after quitting the shell; the oval, pear-shaped, and
variously contracted forms gradually merging into the characteristic
cone-shaped animalcule (fig. 10). In their fully developed condition,
they exhibit the most lively movements; and to witness several hundreds
of them rushing about with unceasing activity is a curious sight. The
phenomenon, moreover, loses none of its interest from the consideration
that only a few hours, or it may have been minutes, previously, these
now actively gyrating animalcules were lodged _in ovo_ within the
blood-vessels of their human host. From persons who are infested,
myriads of these eggs of _Bilharzia_ daily make their escape during
the act of micturition; and, when this act is accomplished by the
host out-of-doors, it is easy to perceive how readily the ova may be
subjected to conditions favorable to the development of larvæ. The
direct passage of the urine into any considerable receptacle of natural
or fresh water would in a few minutes ensure the hatching of all the
eggs; and in the absence of any such direct aid to development, the
accidental occurrence of a shower of rain would, in all localities
where the _Bilharzia_ disease is endemic, readily transfer the ova into
ditches, ponds, rivers, lakes, and ultimately, perhaps, even into the
sea itself.
[Illustration: FIG. 15.--Egg of _Bilharzia_, with the shell adhering to
the escaped ciliated embryo. Original.]
[Illustration: FIG. 16.--Ciliated embryo of _Bilharzia_ in the act of
dying from the escape of the sarcodic contents. Original.]
The behaviour of the embryo under the action of reagents of various
kinds is remarkable. Thus, when on the 5th of Sept., 1870, I placed
some ova in brackish water, of the strength of two parts of fresh
water to one of pure sea-water, their contents were readily developed,
though the escaping embryos did not swim vigorously. When again I
placed some other eggs in pure sea-water, their contained embryos
became instantly transfixed, the vibratile cilia of the head being
rigid and motionless. At first I naturally concluded that the embryos
were killed outright; but, to my great surprise, the shock passed away
in about half an hour, when they revived and were soon afterwards
hatched. One of the larvæ thus set free carried off several of the loose
intra-chorional globules which had, during the period of transfixion,
become firmly adherent to the ends of the caudal cilia. Here I may
remark upon a decided difference observable between the cilia of the
head and body respectively. The former are at all times vibratile,
active, and conspicuous, whilst the latter are more delicate, capable
of comparatively little motion, and partaking more of the character
of fine setæ. In length their general measurement varies from 1/2500″
to 1/2000″. The action of pure sea-water on the free animalcules,
previously immersed in fresh or brackish water, was equally striking.
All, without exception, immediately became paralysed and almost
motionless; nevertheless, on again adding fresh water, several entirely
recovered. It is worthy of notice that in these cases the cephalic
cilia furnished the first indications of returning viability. I was
particularly struck with the behaviour of one embryo, which, under
the stimulus of the sudden shock, retracted its cone-shaped head
almost entirely within the general cavity of the body (fig. 14, lower
specimen). In their moribund condition, whatever shape the embryo
retained, the sarcodic contents gradually faded away; the outline of
the creature, however, becoming more marked (fig. 16). Usually the body
of the animalcule became elongated whilst expiring in sea-water. Under
other circumstances the embryo frequently bursts; the sarcodic contents
escaping in the form of amœba-like bodies and the cilia retaining their
powers of movement long after all traces of the sarcode have disappeared.
[Illustration: FIG. 17.--Ciliated embryo of _Fasciola hepatica_, showing
the so-called eye-spot. After Leuckart.]
The larvæ of _Bilharzia_ closely resemble those of _Fasciola hepatica_,
which latter may be appropriately noticed in this place. The ciliated
embryo of the common liver fluke has the form of a long cone inverted;
the anterior end or head being flatly convex. In the centre is a short
proboscis-like papilla destitute of cilia (fig. 17). The general
covering of cilia rests on a well-defined granular epidermis; this
latter being succeeded by a dense peripheral layer of large nucleated
cells, each of them measuring about 1/2500″ in diameter. The epidermis
measures 1/6250″ in thickness. In the central mass of parenchyma no
internal organs are recognisable, but Leuckart observed indications of a
canal which he thought might open at the tail, though the opening itself
was not actually visible.
As long as the ciliated covering remains intact the embryo, like other
animalcules, displays great activity, whirling round and round on
its own axis, and also describing gyrations and circles of different
degrees of range in the water, the latter movements being accomplished
by bending the body upon itself to a greater or lesser curvature. The
embryos of _Bilharzia_ and other infusoria exhibit the same behaviour,
and, as Leuckart observes, when these embryos knock against any
obstruction, they pause after the blow, as if to consider the nature
of the substance they have touched. As in the case of fluke embryos
generally, the ciliated covering eventually falls off and the embryo
reassumes a more or less oval figure, at the same time changing its
swimming mode of progression for the less dignified method of creeping.
In the free ciliated condition the embryo of the common liver-fluke
measures, according to Leuckart, 1/190″ in length, the anterior broad
end being 1/500″. The cilia have a longitudinal measurement of 1/1388″.
According to the observations of Dr Willemoes-Suhm, the cilia of the
embryos of the _Distoma megastoma_ are limited to the anterior pole of
the body. This is also the arrangement, as Leuckart first pointed out,
in _Distoma lanceolatum_ (fig. 18). On the other hand, Pagenstecher has
shown that the embryos of _Distoma cygnoides_ and _Amphistoma_
(_Diplodiscus_) _subclavatum_ are ciliated all over, an observation
which, as regards the latter species, has been confirmed by Wagener and
others. Dr Pagenstecher’s original statement to the effect that
“intrachorional germs of trematodes offer no distinctive characters,”
must, therefore, in the present state of our knowledge, be accepted as a
general conclusion admitting of many exceptions. In the early stages of
development the embryo of _Distoma lanceolatum_ occupies the centre of
the egg, and according to Leuckart has its conical head invariably
directed towards the upper pole of the shell, or, in other words, to
that end of the egg which is furnished with a lid-like operculum.
Leuckart describes the embryo itself as “finely granular and armed at
the tip with a dagger-like spine, which, with the simultaneous
displacement of the adjacent granular mass, can be pushed forward and
drawn back again.” Besides this so-called cephalic granular mass, there
are within the embryonic body two other granular masses widely separated
from each other, but occupying the posterior half of the embryo. These
Leuckart supposes to be the rudiments of a future brood, to be developed
at the time when the free embryo shall have lost its ciliated swimming
apparatus, shall have bored its way by means of the cephalic spine into
the tissues of a mollusk, and shall have become metamorphosed into a
sac-like larva (Nurse, Sporocyst, or Redia, as the case may be).
Whatever be the full significance of these internal developments, we
have at least satisfactory evidence that the complete and free embryo is
a globe-shaped animalcule, having the anterior third or cephalic end of
the body covered with cilia, and armed with a central boring spine. In
consequence of this limitation of the ciliated covering, its swimming
movements are less vivacious than those of the embryo of _Fasciola
hepatica_; it will, therefore, probably take up its residence in a less
active host than that chosen by the embryo of Fasciola, selecting one of
those mollusks which either move slowly or are prone to keep at the
bottom of the water. The mature eggs have a length of 1/625 to 1/555 of
an inch, and a breadth of 1/833″. The long diameter of the free embryo
varies from 1/990″ to 1/833″, the transverse diameter being 1/1562″.
Whilst the embryos were still in the egg Leuckart could see no ciliary
motion. With most observers, both the ciliary apparatus and the boring
spine appear at this stage to have altogether escaped observation.
[Illustration: FIG. 18.--Ciliated embryo of _Distoma lanceolatum_. After
Leuckart.]
As regards the intimate structure of the ciliated embryo of _Bilharzia
hæmatobia_, I have further to observe that, shortly after its extrusion
from the shell, the hitherto loose, globular sarcode particles
coalesce. This is apparently a preliminary step towards the subsequent
differentiation process. Respecting the pedunculated blind sacs formed
within the head, I think that we must regard the largest one as
representing the stomach of the larva in its future cercarian stage.
Under the 1/12″ objective I distinctly recognised, in the cavity of the
central blind sac, numerous highly refracting granules, the diameter of
which averaged not more than 1/12000″. The rudimentary stomach is often
traceable whilst the larva is still within the egg. It measures about
1/500″ in length, including the peduncle, and 1/14000″ in breadth. The
width of the narrow stalk does not exceed 1/9000″. The other two-stalked
bodies appeared to have the character of _lemnisci_. They were
occasionally well seen whilst the embryo was still within the egg. As
regards the integument, it is easy to recognise two layers. In careful
adjustments of the focus the inner wall of the transparent dermis
presents a beaded appearance. These minute and regular markings do not
undergo alteration during the contractions of the body of the larva.
[Illustration: FIG. 19.--Outline representation of a ciliated embryo
of _Bilharzia_, showing the arrangement of the water vessels and the
vacuoles. Original.]
A highly developed water-vascular system exists in these little
animalcules. On many occasions I saw traces of this set of vessels,
and in several instances I obtained a most satisfactory view of the
entire series of branches. Anxious to receive confirmation of my
discovery, I demonstrated the existence of these vessels to a skilled
microscopist--the late Mr J. G. Pilcher, of H. M. Army. In the briefest
terms it may be said that the water-vascular system of _Bilharzia_,
in the larval condition, consists of two main stems, which pursue a
tortuous passage from head to tail, and which, in the course of their
windings, give off several anastomosing branches (fig. 19). As also
obtains in the corresponding larvæ of _Diplodiscus subclavatus_, there
is no excretory outlet visible at the tail.
Encouraged by the experiences and determinations of Pagenstecher,
Filippi, Wagener, Leuckart, and others, I sought for the intermediate
hosts amongst fresh-water mollusks and small crustacea. Failing of
success in these, it occurred to me that the larvæ of _Bilharzia_ might
normally reside in fluviatile or even in marine fishes. This latter idea
seems also to have struck Dr Aitken. In an appendix to his ‘Report to
the Army Medical Department for 1868,’ dated from Netley, Nov., 1869,
he gives a figure of a nurse-form, which he terms a cercaria, from the
tail of a haddock--suggesting for _Bilharzia_ some genetic relation. Dr
Aitken also extends his views in reference to certain larval trematodes
alleged to have been found in the so-called Delhi boils and Lahore
sores. These parasitic forms have, however, been shown by Dr Joseph
Fleming to be nothing more than altered hair-bulbs (‘Army Med. Reports,’
1868-69).
In regard to the flukes from the haddock, I have satisfied myself that
these immature trematodes from the nerves of the cod-tribe can have no
genetic relation with _Bilharzia_; and I think it due to Dr Maddox to
say that I accept his conclusion respecting them. In his paper (‘Micros.
Trans.,’ vol. xv, 1867, p. 87) he offers strong proof that the so-called
_Distoma neuronaii Monroii_ of the haddock (_Morrhua æglefinus_) is
the juvenile condition of _Gasterostoma gracilescens_ of the angler
(_Lophius piscatorius_).
I am sorry to have to state that all my experiments proved negative. I
tried to induce the ciliated embryos to enter the bodies of a variety
of animals, such as Gammari, Dipterous larvæ, Entomostraca, Lymnæi,
Paludinæ, different species of Planorbis, and other mollusks; but
neither in these, nor in Sticklebacks, Roach, Gudgeon, or Carp, did they
seem inclined to take up their abode.
The very peculiar and formidable helminthiasis produced by this
parasite has been thoroughly investigated by Griesinger and Bilharz,
and it has been fully described in the standard works of Küchenmeister
and Leuckart. My own case from Natal also supplied many interesting
clinical facts which were published in my ‘Lectures on Helminthology,’
quoted below. The comparative prevalence of this disorder in Egypt is
well established. Symptomatically, its principal feature consists in a
general disturbance of the uropoietic functions. Diarrhœa and hæmaturia
occur in advanced stages of the complaint, being also frequently
associated with the so-called Egyptian chlorosis, colicky pains, anæmia,
and great prostration of the vital powers. The true source of the
disorder, however, is easily overlooked unless a careful microscopic
examination be made of the urine and other evacuations. If blood be
mixed with these, and there also be a large escape of mucus, a minute
inspection of the excreta will scarcely fail to reveal the presence of
the characteristic ova of _Bilharzia_. Besides the increase of mucus
secretion, there may even be an escape of purulent matter, showing that
the disorder has far advanced. The patient’s constitution eventually
becomes undermined; pneumonia often sets in, and death finally ensues.
On making post-mortem examinations the following pathological facts come
to light. In cases where the disease has not advanced very far, minute
patches of blood-extravasation present themselves at the mucous surface
of the bladder, but in more strongly pronounced cases the patches
are larger or even confluent. In some instances there are villous
or fungus-like thickenings, ulceration and separation of portions of
the mucous membrane, with varying degrees of coloration, according to
the amount of the extravasation, which becomes converted into grey,
rusty-brown, or black pigment deposits. A gritty or sandy deposit is
often superimposed, consisting of ordinary lithic-acid grains mixed
with eggs and egg-shells. Eggs are readily detected in the urine, these
having escaped from the ruptured vesical vessels. The lining membranes
of the ureters and renal cavities are also more or less affected; the
kidneys being frequently enlarged and congested. It must, however, be
borne in mind that in all these organs the true seat of the disorder is
the blood, which forms the proper habitat of the _Bilharzia_; and this
being the case, the worms as well as their escaped eggs may be found
in any of the vessels supplying the diseased organs. In one instance,
quoted by Leuckart, Griesinger found a number of empty eggs in the left
ventricle of the heart, and from this circumstance it was supposed that
they might be carried into various important organs, or even plug up
the larger vessels. As before stated, however, the parasites are more
particularly prevalent in the vessels of the bladder, mesentery, and
portal system. The effects upon the intestinal mucous membrane are, in
most respects, similar to those occurring in the urinary organs. Blood
extravasations, with thickening, exudation, ulceration, and fungoid
projections, appear in and upon the intestinal mucous and submucous
tissues; these appearances, of course, being more or less strongly
marked according to the degree of infection.
In regard to the treatment of the helminthiasis, I am precluded from
entering into details here; nevertheless, I am glad to perceive that
the principles which I long ago enunciated have received approval both
at home and abroad. As stated in my ‘Lectures’ our object should be not
to interfere with, but to promote nature’s curative efforts. If I read
the pathological facts correctly, she seeks to bring about this result
by erecting artificial barriers which serve to moderate the bleeding.
In this way, under ordinary circumstances, the life of the bearer is
sustained, or held in the balance until the parasites either perish or
cease to be capable of causing active disease. Depend upon it, this
is the principle which should guide physicians in their treatment of
the Bilharzia disorder. If the adult parasite were merely attached
to the lining membrane of the bladder, then powerful diuretics and
medicated injections would probably prove serviceable; but since the
entozoa reside in the blood we must be careful not to increase the
patient’s troubles. In the case of intestinal worms the most powerful
parasiticides may be prescribed without let or hindrance; but that drug
must be a truly subtle worm-poison which, when taken into the system,
shall kill the blood-flukes without exerting any injurious effects upon
the parasite bearer.
When, in 1872, I published my lectures on helminthology, I remarked
that it was not improbable that, ere long, many more cases of Bilharzia
disease would be brought to light. What has been added in this respect
is chiefly due to the researches of Sonsino, but a case of some interest
has been recorded comparatively recently by Dr W. K. Hatch, stationed
at Bombay. From the particulars furnished it seems evident that the
victim, an English gentleman, contracted the disease by drinking water,
either in Arabia or in Egypt, in which latter country, however, he had
only sojourned fifteen days. From the patient’s statements it appears
that, hæmaturia is frequent amongst the Arabs. Incidentally, Dr Hatch
mentions that Dr Vandyke Carter had informed him that, so early as the
year 1862, he (Dr Carter) had detected the embryos of Bilharzia in the
urine of an African boy admitted to the Jamsetjee Jejeebhoy Hospital.
The treatment employed by Dr Hatch was that recommended by Dr Harley in
his well-known memoir. Having myself energetically opposed Dr Harley’s
views on pathological grounds, I am not surprised to see it stated
that Dr Harley’s method of treatment effected “no diminution in the
number of the parasites.” As I said in my lectures (now out of print)
it is evident that “nature” in view of moderating the hæmaturia--by the
formation of plugs at the ulcerated points of the mucous surface--sets
up the artificial barriers above referred to; therefore if you
catheterise and employ medicated injections you do more harm than good.
As to the administration of belladonna internally, in view of retarding
development, or of destroying the parasite, no good can be expected
from this source. I certainly obtained better results with buchu and
bearberry (_Arctostaphylos_).
In the matter of sanitation it is quite evident, from the foregoing
data, that the danger of infection cannot arise from the drinking of
impure water, as ordinarily understood. The embryonal larvæ would be
killed by an admixture of sewage. It is obvious that infection can
only occur from swallowing free cercariæ or freshwater mollusks which
contain the higher larval forms in their encysted or pupa condition.
Slow running streams or stagnant pools with sedgy banks are eminently
favorable to the existence and multiplication of intermediary bearers,
and consequently their waters are dangerous if employed for drinking
purposes.
BIBLIOGRAPHY (No. 12).--_Bilharz_, in Siebold and Köll., ‘Zeitsch. für
wissensch. Zool.,’ iv, 1851.--_Idem_, ‘Wiener medic. Wochenschrift,’
1856.--_Cobbold, T. S._, “On some new forms of Entozoa (_Bilharzia
magna_),” ‘Linn. Trans.,’ vol. xxii, p. 364, 1859.--_Idem_, “Synopsis
of the Distomidæ,” in ‘Proceed. Linn. Soc.,’ vol. v, Zool. Div., p.
31, 1860.--_Idem_, “Remarks on Dr J. Harley’s _Distoma capense_,” in
‘Lancet,’ also in the ‘Veterinarian,’ and in ‘Intell. Observer’ for
Feb. and March, 1864.--_Idem_, “Entozoa,” l. c., p. 197, 1864.--_Idem_,
“On Blood Worms,” Lecture xx in ‘Worms,’ l. c., p. 145 et seq., 1872;
Tommasi’s edit., Vermi, p. 141, 1873.--_Idem_, “On the Embryos of
_Bilharzia_,” ‘Brit. Assoc. Rep.,’ 1864.--_Idem_, “On the Development
of _Bilharzia hæmatobia_, together with Remarks on the Ova of another
Urinary Parasite occurring in a case of Hæmaturia from Natal,” ‘Brit.
Med. Journ.,’ July, 1872; repr. in the ‘Veterinarian,’ 1872.--_Idem_,
‘New Entozootic Malady, &c.’ (brochure), London, 1865.--_Idem_,
“Helminthes,” in Gunther’s ‘Record of Zool. Literature,’ p. 617,
1865.--_Idem_, “Entozoa in relation to Public Health and the Sewage
Question,” Rep. of the Proceed. of the Metrop. Assoc. of Officers
of Health, in ‘Med. Times and Gazette,’ Jan., 1871, repr. in the
‘Veterinarian,’ p. 359, 1871.--_Idem_, “Verification of recent
Hæmatozoal Discoveries in Australia and Egypt,” ‘Brit. Med. Journ.,’
June, 1876.--_Idem_, “On Sewage and Parasites, especially in relation
to the Dispersion and Vitality of the Germs of Entozoa,” rep. in
‘Med. Times and Gaz.’ for Feb., and the ‘Veterinarian’ for May,
1871.--_Davaine, C._, l. c., ‘Synops,’ and p. 312, 1860.--_Diesing,
C. M._, ‘Revis. d. Myzelmith,’ Vienna, 1858.--_Griesinger_, “Klin.
und Anat. Beobachtungen über die Krankheiten von Egypten,” in ‘Arch.
für physiol. Heilkunde,’ 1856.--_Idem_, ‘Gesammelte Abhandlungen,’
Berlin, 1872.--_Idem_, ‘Arch. d. Heilk.,’ 1866.--_Harley, J._, ‘On
the Hæmaturia of the Cape of Good Hope, produced by a Distoma,’ rep.
in ‘Lancet,’ and ‘Med. Times and Gaz.,’ Feb., 1864; also in Ranking’s
‘Abstract,’ p. 173, 1864, and fully in ‘Medico-Chirurg. Trans.,’
1865.--_Idem_, “On the Endemic Hæmaturia of the South Eastern Coast
of Africa,” ‘Med.-Chir. Trans.,’ vol. liv, 1871.--_Idem_, in Hooper’s
‘Vade Mecum,’ 1869.--_Hatch, W. K._, “Case of _Bilharzia hæmatobia_,” in
‘British Medical Journal,’ Dec. 14, 1878, p. 875.--_Küchenmeister, F._,
‘Parasiten,’ 1855; Eng. edit., p. 277, 1857.--_Leuckart, R._, l. c., s.
617, 1863.--_Sonsino, P._, “Richerche intorno alla Bilharzia hæmatobia
in relazione colla Ematuria Endemica dell’ Egitto e nota intorno
un Nematoideo trovato nel Sangue Umano,” ‘Estr. dal Rend., del. R.
Accad.,’ 1874.--_Idem_, ‘Della Bilharzia hæmatobia e delle alterazione
Anatomo-patologiche che induce nell’ Organismo Umano, loro importanza
come Fattori della Morbilità e Mortalità in Egitto, con cenno sopra
una Larva d’Insetto Parassita dell’ Uomo. Estratto dall’ Imparziale,’
Firenze, 1876.--_Idem_, ‘Sugli ematozoi come contributo alla Fauna
Entozooca Egiziana,’ Cairo, 1877.--_Idem_, “La Bilharzia hæmatobia, et
son rôle Pathologique en Egypte,” ‘Arch. Gén. de Médicine,’ for June, p.
650, 1876.--_Idem_, “Intorno ad un nuovo Parassita del bue (_Bilharzia
bovis_),” ‘Estr. dal Rend. del. R. Accad. di Napoli,’ 1876.--_Weinland,
D. F._, l. c., p. 67, 1858.
SECTION II.--CESTODA (Tapeworms).
_Tænia mediocanellata_, Küchenmeister.--This cestode is frequently
spoken of as the unarmed or beef tapeworm. In general appearance it is
very similar to the armed form. It is, however, a larger and broader
animal, being at the same time rather stouter. It varies usually
from fifteen to twenty-three feet in length, but specimens have been
described as attaining thirty feet. It is called the unarmed tapeworm
in consequence of the absence of any coronet of hooks on the head;
and consequently, also, from there being no prominent rostellum or
proboscis. The place of the last-named structure, however, is supplied
by a small rudimentary disk, which I have seen protruded on pressure
(fig. 20). Usually this disk forms a more or less conspicuous cup-shaped
circular depression, which has been compared to and described as a fifth
sucker. That it is not, in any structural sense, comparable to the true
suckers, I have had abundant opportunity of ascertaining; nevertheless,
I do not doubt that it is to a slight extent capable of being used by
the parasite as a supernumerary holdfast. The anchorage thus secured,
however, is by no means equal to that obtained by the armed species.
This explains the comparative difficulty we find in procuring a specimen
of the armed tapeworm with the head attached.
[Illustration: FIG. 20.--Head of _Tænia mediocanellata_. Showing the
calcareous corpuscles, suckers, rudimentary proboscis, and water
vessels. Highly magnified. Original.]
The establishment of this species as distinct from _T. solium_ is due
to Küchenmeister; but it is curious to observe how accurately this
determination was foreshadowed by the shrewd naturalist and theologian,
J. A. E. Goeze, who clearly indicated two forms of the common tapeworm,
remarking (l. c., Bibl. No. 1, s. 278):--“Die erste ist die bekannte
grosse, mit langen dicken und gemästeten Gliedern, die ich _Tænia
cucurbitina, grandis, saginata_, nennen will.” The same author (s.
245) pointed out the resemblance subsisting between the tapeworm of
the cat (_T. crassicollis_) and the vesicles (“Krystallblasen”) and
their contained “erbsförmige Blasen” (_Cysticercus fasciolaris_) of the
mouse. Thus the celebrated pastor of St Blasius, in Quedlinberg, almost
contemporaneously with Pallas, early arrived at the conclusion that the
hydatid-measle was a kind of tapeworm.
[Illustration: FIG. 21.--Free proglottides of _Tænia mediocanellata_.
After Leuckart.]
Respecting the organisation of this worm I may observe that the mature
joints have a more complicated uterine organ than obtains in _Tænia
solium_, presenting nearly double the number of lateral branches.
They are more closely packed, running outwardly in an almost parallel
manner. The first sexually mature proglottis occurs at about the 450th
joint, but whereas, in the pork tapeworm, only some 200 subsequent
segments share this perfect character in the beef tapeworm, according
to Leuckart, as many as 360 or even 400 mature joint may be present.
The joints are very liable to form monstrosities; these abnormalities
sometimes affecting the reproductive organs, which become doubled
or even trebled. In the Hunterian collection there is a proglottid
showing twenty-two sexual orifices. Dr Cullingworth, of Manchester, has
described a specimen in which the joints are curiously tripartite.
As already hinted the true source of this parasite has been proved by
experiment; the first successful worm-feeding having been accomplished
by Leuckart. Mosler’s, and subsequently my own feeding experiments,
immediately followed. Other successful experiments with this species
have been conducted by Zurn, Probstmayer, St Cyr, Perroncito, Masse and
Pourquier, and Zenker. As will be again mentioned below Dr Oliver, R.A.,
whilst stationed at Jullundur, successfully reared the adult tapeworm in
a Mohammedan groom and in a Hindoo boy. It will also be seen that Prof.
Perroncito reared the worm in a student in fifty-four days. In my own
experiments on animals I was assisted by Professor Simonds. The feeding
materials were tapeworms expelled from my own patients. We obtained the
following interesting results:
_Exp. 1._--A calf. First feeding, Dec. 21st, 1864. Marked symptoms.
Slaughtered April 3rd, 1865. Result positive.
_Exp. 2._--A calf. First feeding, April 13th, 1865. Second, third, and
fourth feedings in May and June. No symptoms. Died on Sept. 3rd, 1865,
after thirty-six hours’ illness with “cattle plague.” Result stated to
have been negative as far as the muscles were concerned. Viscera not
examined.
_Exp. 3._--A Dutch heifer. First feeding, March 3rd, 1865. Three
subsequent feedings. Symptoms only slight. Slaughtered April 4th, 1866.
Result positive. Measles especially numerous in the diaphragm, but all
had undergone calcareous degeneration.
_Exp. 4._--A calf. Fed May 27th, 1872, with ripe proglottides. Marked
symptoms set in on June 7th, which began to abate on the 12th, and had
nearly disappeared by the 20th of the same month. The record of the
post-mortem result has been lost; but the animal was infected.
_Exp. 5._--A calf, which had been made the subject of a “glanders
experiment.” First fed on Oct. 17th, 1872, and thrice in the following
year, Jan. 1st and 11th, and March 8th. No symptoms having appeared the
animal was kept for six or eight months after the last feeding. Seeming
to be free from disease of any kind, it was sold as a sound heifer.
_Exp. 6._--A young heifer calf, of six months. Fed Oct. 18th, 1873,
with the mature proglottides of a large beef tapeworm. No symptoms.
Slaughtered several months afterwards. Result stated to have been
negative. Unfortunately I was not present at the autopsy.
_Exp. 7._--A young heifer. First fed May 19th, 1874, with the joints of
a tapeworm, and again on June 12th. No apparent ill effects resulted,
but the animal died in October. At the post-mortem examination, made
by Prof. Simonds, no parasites were observed. Subsequently I found
calcareous specks in the liver which proved to be degenerated measles.
_Exp. 8._--A calf. Fed on or about March 24th, 1875, with sexually
mature joints. The calf was put to and remained with a foster mother
until it died from disease of the larynx on the 15th of the following
July. The animal was ill-treated by its foster parent, and at the
post-mortem I observed a large intercostal cicatrix, evidently
the result of injury. In this case I devoted several hours to the
exploration of the muscles and viscera. Not a trace of the _Cysticercus
bovis_ could be found in the muscles or connective tissues, but the
liver contained scores of perfectly developed measles, besides hundreds
of others in various stages of calcareous degeneration. On comparing
some of the latter with those I had obtained from the preceding
experiment the pathological appearances were at once seen to be
identical. It was easy to find and pick out the measles in their cysts
from the naturally friable liver. I also detected four Cysticerci in the
lungs, two of which had degenerated. Microscopic examination confirmed
my interpretation of the naked-eye appearances.
[Illustration: FIG. 22.--Section of the heart of a calf infested by
cestode larvæ. After Mosler.]
Fragmentary as the above data are, they serve to show that we have
hitherto been too hasty in concluding that beef and veal measles reside
only in the voluntary and striated muscles of their hosts. The facts
here recorded prove that the liver of a calf may be extensively invaded
by cysticerci, and yet the animal will exhibit no sign of constitutional
disturbance. The cestode tuberculosis may come and go without any
diagnostic symptom, whilst a few months suffice for the natural death
and decay of the parasite by calcareous degeneration. Thus it becomes
extremely probable that many experiments hitherto regarded as negative
in their results have really been positive; the pathological evidences
having been either misinterpreted or altogether overlooked. Every
pathologist is familiar with gritty particles in the various viscera
of man and animals, but few are probably aware how constantly these
are dead and degenerated Cysticerci. The gritty particle itself may be
reduced to the merest point, no larger than the _receptaculum capitis_
of the Cysticercus itself, and in course of time it will disappear
entirely. Practically it is satisfactory to have experimental evidence
of the fact that cattle, as well as other animals, however extensively
measled they may have been, can become thoroughly cleansed of the
disorder by nature herself. It is only necessary that the diseased
animals be separated from infectious influences.
Although the beef measle has never yet been found in man, I have for
convenience sake introduced the facts of larval parasitism in this
place. The sanitary bearings of this subject are far too important to
be dismissed in a summary manner. I have shown that the prevalence or
rarity of the beef tapeworm in man is strictly dependent upon the habits
of the people; this same cause operating to produce healthy or diseased
meat-food, according to the degree of civilisation. In this connection
the oft-quoted statements of Kaschin respecting the prevalence of
tapeworms among the Burätes, and the well-known frequency of this
entozoon in Abyssinia, need only be alluded to.
When discussing the food question in my ‘Manual,’ I freely availed
myself of facts privately communicated by Dr. Joseph Fleming, and I
especially referred to the published labours of Lewis, Hewlett, Veale,
and other observers stationed in India. Beef measles are extremely
common in the cattle of the north-west provinces of India, so much
so that severe restrictions have been imposed upon the consumption
of ration beef. The presence of a few measles in the flesh of cattle
has been deemed a sufficient excuse for condemning and burying entire
carcases. The measle is easily distinguished from that of mutton and
pork by the fact that its head is not furnished with hooks, whilst in
the place of a rostellum there is a small, centrally placed, retractile
disk, which assumes the appearance of a supplementary sucker as in the
adult worm. The four true suckers are also comparatively large. The
measle usually varies in size from the fourth to the half of an inch in
length, but my cabinet contains a specimen nearly an inch long. This
was contributed by Dr J. Fleming, who mentions having seen a measle
which, when unrolled, measured nearly an inch and a half in length.
Although thousands of these bladder worms must exist in the cattle of
England, up to the present time not a single instance has been recorded
of the occurrence of these cystic parasites in the United Kingdom,
except in our experimental animals. Notwithstanding my inquiries, I
have not yet found a butcher, flesher, meat-inspector, or veterinarian,
who has encountered this parasite in any animal slaughtered for the
market. Several butchers have denied their occurrence in meat sold by
themselves. Even so late as June, 1874, the presence of measles in the
flesh of cattle was denied before an assembly of French _savans_; yet
for many years past I have constantly exhibited measly beef and veal in
the lecture room of the Royal Veterinary College. (See the discussion of
the Société de Thérapeutique, recorded in the ‘Bullétin Gén. de Thér.’
for June 30th, 1874, and also the ‘Jour. de Thér.,’ No. 14, for July,
p. 556, where, however, special remarks on this head have been omitted;
see also the ‘Lond. Med. Record’ for July 29th, 1874, p. 472, and the
‘Lancet’ for Dec., 1874, p. 794.) Quite in contrast with the statements
referred to are those of recent Italian observers.
Some few years back Professor G. Pellizzari communicated to the
Medico-Physical Academy, at Florence, the results of a series of
experiments conducted by himself, with the assistance of Dr Tommasi, in
regard to the temperature necessary for the destruction of cysticerci in
measled meat. An account of these experiments is published in Tommasi’s
edition of my ‘Manual.’ The researches were made in relation to certain
sanitary measures effected by the Municipal Commission of Florence,
the express object of these measures being to prevent the injurious
distribution of measly meat, especially that of swine. Signor Bosi, the
superintendent of the public slaughterhouses, granted every facility in
his power. In a previously published memoir by Professor E. Perroncito
it was stated that measly meat (_panicatura degli animali_) required
a higher temperature than that of boiling point for the destruction
of the bladder worms in question. In this opinion Signor Bosi shared.
According to the original memoir of Perroncito we are told that “about
twenty specimens of Cysticerci were collected by the author, and
placed in boiling water. After twenty minutes’ boiling, not one of the
parasites appeared to suffer. The head continued to be drawn into the
body, and when the Cysticerci had their heads drawn out one by one
they still appeared to possess all the elasticity of living bladder
worms, displaying those movements of extension which are proper to
parasites not yet dead. The hooks were observed regularly disposed on
the proboscis, where they formed a double crown, the suckers remaining
intact.” Perroncito remarked, however, that the Cysticerci showed a
coloring tendency towards brown, and he added that “with the aid of
two needles it became easy to lacerate the body of the Cysticercus,
which appeared to be swollen, and possessed of diminished cohesion of
its parts.” It was evident to all eyes, observed Professor Pellizzari,
that these statements involved clear contradictions. Yet again, at page
28 of the memoir, Professor Perroncito wrote:--“During the past winter
I introduced some little slices (_fettuccie_) of muscle-flesh (8 to
10 millimètres in thickness), infested with Cysticerci into a vessel
(_cassolina_) containing fat at the temperature of 190 to 200° Cent.
(374 to 400° Fahr.). At the expiration of ten or fifteen minutes the
slices of meat were fried, and the Cysticerci lying at the surface had
acquired a light brownish colour, as if they were roasted. By breaking
up the slices one could still see the small reddish muscular bundles,
whilst the Cysticerci in the middle remained entire and well preserved.
Their heads displayed the hooks and suckers regularly distributed.” It
is certainly singular, as Pellizzari observes, that these Cysticerci,
having been thoroughly fried and roasted, should still remain alive and
in their normal state; but the ultimate conclusion at which Perroncito
arrived was still more startling, and one which, if it were true, would
not fail to create a considerable stir among our officers of health. On
reviewing the whole matter Perroncito says:--“It appears to me that the
melted fat alone of hogs (_maiali grandinosi_) should be utilised, and I
am pleased to reckon the illustrious Gerlach and all other distinguished
practitioners to be of the same opinion. Permit me, therefore, being
well satisfied also with the results of many other experiments, once
more to advance the conclusion that, if it is not certain that the
Cysticerci die at from 80 to 100° Centigrade (176 to 212° Fahr.), we are
quite sure that they dry up and become completely mummified at 125, 130,
and 150° Cent. (257, 268, and 302° Fahr.), temperatures which we could
easily produce by means of a properly constructed apparatus.”
After remarking upon the serious nature of the conclusion which
Perroncito sought to establish, Professor Pellizzari makes further use
of quotations which bear upon the question as to whether the quality of
the vessels in which the fat of diseased hogs is melted down may not
largely affect the degree of high temperature sought to be obtained (in
view of a perfect destruction of the Cysticerci). Perroncito repeatedly
witnessed the operations of pork-butchers; and when portions of meat
were introduced, with water, into the cauldrons, he always saw that the
temperature “was maintained between 97° and 98° Centigrade.” However,
this part of the question may be dismissed in a very few words, since
Perroncito himself finally allows that “the different composition of the
vessels cannot elevate the temperature of the fat by many degrees.”
With the praiseworthy intention of either verifying or refuting these
conclusions, Pellizzari, with the approval of Bosi and with the
assistance of Tommasi, instituted a fresh series of experiments at a
private laboratory. The details of these experiments are exceedingly
interesting; but as their record occupies several pages of Tommasi’s
appendix already referred to, I must content myself with a general
statement of the results obtained. Professor Pellizzari found that
Cysticerci, so far from requiring a temperature of upwards of 100°
Centigrade for their destruction, die at a temperature of 60° Centigrade
(140° Fahr.). He had, it appears, previously taken the initiative in
recommending certain measures to the Florentine municipality, in view of
protecting the public health, and he had now the satisfaction of more
than confirming the wisdom of these sanitary precautions. In excessively
measled animals the fat is removed and boiled in suitable cauldrons, and
has potash mixed with it to render it useful for industrial purposes.
By the various measures adopted the entire animal is utilised, and with
proper precaution there seems little chance for the measles to arrive at
the tænioid or sexually mature condition.
In the next part of his communication Pellizzari touches upon the
question of measles in beef, referring especially to the experimental
labours of Leuckart and myself. Finding additional support from our
views Pellizzari declared the propositions of Dr Perroncito as of no
value whatever. “But how is it,” he adds, “that notwithstanding that
so low a temperature suffices to kill these cysticerci, yet cases of
Tænia are continually occurring?” The answer to this question will
appear in the sequel; but meanwhile it will be as well to refer to the
recent _brochure_ by Dr Giacomini. This author appears to have had no
opportunity of perusing Pellizzari’s communication already cited, and
consequently it is not surprising that he should, in common with others,
have accepted the original conclusions of Perroncito. Dr Giacomini
clearly perceives that, whatever precautions of a hygienic character are
suitable for the prevention of disease arising out of the consumption
of measly pork, the same, or at all events similar, measures ought
to be adopted with the view of checking tapeworm affections arising
from the ingestion of other kinds of meat, especially veal and beef.
Like Pellizzari, he is satisfied as to the human origin of the small
bladder worms found in cattle, and establishes this position not only
from the oft-quoted experiments of Leuckart and Mosler, but also from
those conducted by myself and Simonds in England, and by Professor
F. Saint-Cyr in France. From a careful review and consideration of
all the facts of the case, he recommended a more complete supervision
over the flesh of oxen before it is employed commercially, and greater
precaution when employing veal as food, by causing it to be subjected
to a high temperature, in order that the parasites may be killed before
it is ingested. It is evident that Giacomini thinks that a temperature
exceeding that of boiling-point is necessary for the destruction of the
beef and veal measles, since he immediately adds, “Though experiments
have not been made with the object of ascertaining the amount of
resistance of heat which the unarmed cysticercus can bear, yet, judging
by those conducted by Professor Perroncito on the measle of the hog,
we are in a position to say that a temperature of 135° Cent. (275°
Fahr.) is necessary for the destruction of an isolated Cysticercus,
whilst the heat should be raised from 150° to 200° Cent. (302° to 392°
Fahr.) for ten or fifteen minutes, in order to ensure the complete
destruction of the Cysticerci encapsuled in the interior of a piece
of meat.” I have abridged this portion of Giacomini’s text, because
his statements are pretty much the same as those already quoted from
Perroncito (as cited by Tommasi). But, in the next place, Dr Giacomini
is in error when he states that experiments had not been performed on
the Cysticerci of the ox. So far from this being the case, similar
experiments had long previously been conducted by Dr Lewis in India; and
these researches had quite as much to do with the measles or Cysticerci
of beef as they had with those of the hog, if not more. Naturally but
few foreign investigators can have had access to the work in which
Lewis’s experiments were originally recorded, and to which, therefore,
I must call their attention. Thus, Dr Tommasi has fallen into the error
of supposing that the investigations of Lewis were made in England. It
is of very little moment where the experiments were carried on, but
Tommasi’s statement (appendix, loc. cit., p. 161), wherein he says that
Pellizzari’s experiments, in which he himself took part (_ai quali
io stesso ho assistito_), are even more complete than those made in
England by Dr Lewis, and in Germany by Dr Küchenmeister, cannot be
allowed to pass unchallenged. If Tommasi had enjoyed the opportunity of
consulting Lewis’s original memoir, he would not have underestimated our
countryman’s labors. The memoir by Lewis is singularly complete, and
well-nigh exhausts all the facts that can have any interest in relation
to the question of public health. Towards the close of his essay he
expressly states, as the result of investigation--“(1) That exposure
to a temperature of 120° Fahr. for five minutes will not destroy life
in Cysticerci, but that they may continue to manifest indications of
life for at least two or three days after such exposure; (2) that
exposure to a temperature of 125° Fahr. for five minutes does not kill
them; but (3) after being subjected to a temperature of 130° Fahr. for
five minutes, they may be considered to have perished. After exposure
to this and higher temperatures, in no instance have I been able (he
adds) to satisfy myself that the slightest movements took place in
their substance when examined even under a high power. At least, it
may be confidently asserted that, after exposure for five minutes to
a temperature of 135° to 140° Fahr., life in these parasites may be
considered as absolutely extinct” (p. 139). Thus the statements of Lewis
and Pellizzari were in perfect accord; and seeing that their conclusions
were alike the result of very careful and independent inquiry, it seemed
as if the question at issue was finally solved. These investigations
made it perfectly clear that Cysticerci of all kinds, whether found in
veal, beef, or pork, could not retain their vitality when exposed to a
temperature of 60° Centigrade, or, in other words, 140° Fahr.
The rather severe strictures made on Perroncito’s earlier experiments
induced the Turin professor to go over the subject more carefully, when
he obtained excellent results. He finally ascertained that Cysticerci
perished at a temperature below 50° C. (122° Fahr.). In May, 1877, Dr
Perroncito furnished me with an account of his researches. With the
exception of a few verbal alterations, for which I am responsible,
Perroncito wrote as follows:
“In order to resolve the highly important question of the tenacity of
life of the Helminths and corresponding larval forms, I made since 1871
a very long series of experiments on the _Cysticercus cellulosæ_, which
were published almost at the same time with others of the same kind,
made by Dr Lewis in Calcutta. Towards the end of 1874 Mr Pellizzari,
of Florence, disputed the results of the investigations which I had
made known two years before, _i.e._ in 1872, and agreed with Dr Lewis,
who had stated already that the _Cysticercus_ exposed to a temperature
of 55° C. can be held for dead after five minutes, and also with Dr
Cobbold, who thought the temperature of 60° C. quite enough to kill it.
But the characters he (Mr Pellizzari) relied upon, needing the exactness
and precision required to enlighten and persuade in the most important
scientific questions, gave rise to a mistrust in the most scrupulous
amongst the men devoted to biological pursuits and to several hygienic
measures on the part of the sanitary inspectors with regard to infected
pork. Therefore, my conclusions, argued from the experiments made in
1871-72, were still those followed by the most important Italian cities,
and approved in principle by the superior Board of Health in 1873. I
expressed doubt then about the _Cysticercus_ dying at a temperature
lower than 100° C., and some person misconstrued these doubts, saying
that I had contradicted myself in my work. However, as I could not
assert they died at 80°--100° C., I only noticed the alteration of color
and cohesion which happened in the _Cysticercus_ exposed to various
degrees of temperature, to the end that I might contribute usefully to
the solution of the difficult question, and concluded that ‘if we could
not be sure of the _Cysticercus_ dying at 80°-100° C., it was certain
at all events that they perished at 125° or 130° C.’ Not wishing to
prejudice the question, I never said that they did not die at 80°--100°
C., but simply stated that at this temperature we could not be certain
of their death.
“Now, after a large number of experiments, I have been able to
ascertain with exactness the lowest degree of temperature required to
kill infallibly the _Cysticercus_ and other parasites of animals. The
means I made use of for this kind of investigation were Mr Schulze’s
heating table, the neutral tincture of carmine, the tincture of
hæmatoxylon, and breeding experiments.
“My method is founded essentially--
“(_a_) On the fact that the _Cysticercus_ when it is fresh and is
stretched and conveniently prepared in pure water, or in chloride of
soda very much diluted, and afterwards brought gradually from the
temperature of the ambient air to that of the body of higher animals and
to degrees of heat still more elevated, until life is extinct, keeps
moving to and fro with more or less energy throughout its body, using
especially its suckers and proboscis.
“(_b_) On the greater imbibing power of the dead tissue generally, which
is undoubtedly far more apparent in insects and plathelminths.
“(_c_) On the experiments made to ascertain the value of the two
above-stated facts.
“If, after having prepared a _Cysticercus_, newly extracted from a pig
in the way we have pointed out, we examine it with a microscope on M.
Schulze’s heating table, we find that usually it begins to move after
30° or 35° C., and each moment with greater activity, especially after
38°, 40°, 42°, 44°, 45° C. The temperature being raised progressively,
we see that the _Cysticercus cellulosæ_ puts a stop to its movements
occasionally at 45-46° C., seldom at 47° C., more frequently at 48°
C., sometimes at 49° C.; and, in fifty and more experiments, only one
_Cysticercus_ was able to live on beyond 49° C., standing still at 50° C.
“As soon as it stands still the parasite is dead. In fact, if we
lower again the temperature gradually to that of the ambient air,
and if afterwards we raise it a second time, we pass through all the
intermediate temperatures without the Cysticercus showing the least
signs of life.
“But a more convincing proof of the death of the parasite is got from
the greater imbibing power of the tissue when life is extinct, the same
over the whole body of the plathelminths, and their larval forms. If
we dip the _Cysticercus_ alive with its head stretched in the neutral
tincture of carmine or hæmatoxylon we can leave it there even two, four,
eight, ten, or twelve hours and more, without the head coloring or a
real imbibition taking place; this begins only after the _Cysticercus_
is dead, so that if the _Cysticercus_ is brought first to a temperature
hot enough to kill it (with M. Schulze’s tables to one of 48°, 49°, 50°
C.) and dipped afterwards in the above-mentioned tinctures, it colors
intensely in less than 45°, beginning from the head, and onwards to the
extremity of the cyst of the tail. The head colors more intensely and
rapidly than the neck, as it is covered with very numerous calcareous
corpuscles, which are not met with so frequently in the remaining part
of the body.
“_Cysticercus cellulosæ_ of the pig, and that of the _Tænia
mediocanellata_ of the calf, brought gradually to a final temperature,
the first of 50° C., and the second of 44°, 45°, and 47° C., and then
swallowed alone, or with a piece of butter or crumb of bread, never
produced the _Tænia_ in the valiant students who voluntarily undertook
to make the experiment of swallowing them.
“My investigations were extended to other kinds and forms of Helminths,
and the results were always the same, so that, abiding by the same
principles, I was able to ascertain that--
“1st. The _Cysticercus cellulosæ_ of the pig dies sometimes at 45°
C., more frequently at 47° C., ordinarily at 48° C., very seldom
reaches alive 49° C., and is quite an exception when it resists for
a few moments the temperature of 50° C., so that we can say that the
_Cysticercus_ brought gradually up to this temperature most assuredly
dies if it is kept there longer than one minute.
“2nd. A _Cysticercus cellulosæ_, extracted by Professor Raymond from the
conjunctiva of a child’s eye, died between 45° and 46° C.
“3rd. The _Cysticercus_ of the _Tænia mediocanellata_ dies sometimes at
44° C., very often at 45° C., and does not resist a temperature superior
to 46° C.
“4th. The _Cysticercus pisiformis_ of the rabbit, like the _cellulosæ_,
dies sometimes at 45° and 46° C., but generally stands still and
perishes at 47° and 48° C.
“5th. A _Cysticercus tenuicollis_ died at 49° C.
“6th. The _scolici_ of the _Cœnurus cerebralis_ of a sheep died at 42° C.
“7th. The _scolices_ of the cysts of _Echinococcus polymorphus_ die
generally between 47° and 48° C., and in no case amongst those I have
experimented on did it reach 50° C. alive.
“8th. The _Tænia cucumerina_ died, one at 43° C., and a second parasite
at 45° C.
“9th. A few individuals of _Tænia serrata_ of the dog died at 50° C.
“10th. Two individuals of _Tænia perfoliata_ of the horse died, the
first at 45° C., the second at 50° C.
“11th. The embryos of the _Filaria microstoma_ of the horse began to
stand still at 46-47°, and all died at 48° C.
“12th. The embryos of the _Filaria megastoma_ of the horse’s stomach
died at 47° C.
“13th. The _Trichina spiralis_, both free and in a cyst, in several
experiments always died at 48° C.
“14th. The embryos of the _Strongylus filaria_ of the sheep stood still
at 50° C.
“15th. Probstmayer’s viviparous oxyurids, the infusoria of the colon and
cæcum of the solipeds, and the psorosperms of the liver of the rabbit
did not stir at all.
“Each experiment lasted about ten minutes, and the temperature rose from
8-10° C. to 45-46° C. in six to eight minutes; and from 46° to 50° in
one minute. These experiments have a great value, both scientific and
practical, as they show, on one side, which is the lowest intensity of
heat sufficient to kill always the _Cysticercus_, the _Trichina_, and
other parasites, reducing thus by far the tenacity of life generally
attributed to a large number of Helminths and corresponding larval
forms. They assure us, moreover, of the harmlessness of the flesh
infected by the above-mentioned parasites, when it is cooked in such
a manner as to reach the temperature of 50° C. over all points of the
pieces, even though it be kept at such a degree of heat not longer than
five minutes.
“In a piece of leg of pork the _Cysticerci_ were found alive in all
places not yet putrefied twenty-nine days after the animal had been
slaughtered. On the other hand, in the dry muscles of a calf the
_Cysticerci_ of the _Tænia mediocanellata_ were all found dead fourteen
days after the slaughtering of the animal. I have ascertained that
putrefaction of the flesh is fatal for the two larval forms of these
different kinds of helminths.”
In a subsequent communication received from Professor Perroncito towards
the close of the year 1877 he writes:
“At the last meeting, held on April 23rd, I made a statement to
the Medical and Surgical Society of Turin, of the results of other
experiments tried by heating at M. Schulze’s table and by the
imbibitions with the neutral tincture of carmine, through which I came
to the conclusion that the _Cysticerci_ of the _Tænia mediocanellata_
die sometimes at 44° C., now and then at 45° C., and always at 46° C.
I therefore concluded that they could in no case survive at 47° C. and
48° C. when they were maintained at this temperature at least five
minutes. But to the end of more fully corroborating the facts I had
thus communicated, I, contemporaneously with these, made some breeding
experiments with the same _Cysticerci_ on bold and courageous students
who generously offered themselves for the benefit of science.
“Consequently I am now enabled to state that neither Mr Gemelli nor
Dr Ragni contracted the _Tænia_, though each of them had eaten a
_Cysticercus_ of the _Tænia mediocanellata_ previously, and respectively
subjected to a temperature of 45° C. and 47° C. The larvæ were properly
prepared and submitted to gradual heating on the above-mentioned table,
and swallowed when they no longer gave signs of life. In like manner no
generation of the _Tænia_ took place in the body of Mr Martini, who ate
the _Cysticercus_ brought to a temperature of 44° C. It was maintained
at this degree of heat during a period of about three minutes, and
swallowed whilst a very slight movement was still visible in a portion
of its neck.
“In another student, on the contrary, who ate a living _Cysticercus_
of the _Tænia mediocanellata_, the tapeworm reached its maturation in
fifty-four days and eliminated the two first proglottides. It threw
off two more on the fifty-eighth day, and thirty on the sixtieth.
Sixty-seven days after swallowing the _Cysticercus_ this courageous
young man, having, like his three companions, taken some kousso and
castor oil, emitted the strobila. It was furnished with 866 rings, but
destitute of the neck and head. Its measurement afforded a total length
of 4·274 mètres.
“Adding now to the 866 proglottides the thirty-four already eliminated,
900 would be the number of the segments; and reckoning the length of
each of the latter to be fourteen millimètres, we should have had the
_strobila_ (deprived of the head and neck) reaching a length of 4·75
mètres. Further, calculating the head and neck to be eight millimètres
long, a total length of 4·83 mètres would be the result.
“From all these facts we may conclude that the _Tænia_ has, in our
instance, reached an approximative length of seventy-two millimètres a
day, affording a daily production of 13·43 proglottides.”
In relation to requirements of state medicine I have thought
Perroncito’s researches sufficiently valuable to be quoted at some
length; but their chief interest culminates in the worm-feeding
experiments. Excellent in all respects as was the conduct of the
medical students who, with Professor Perroncito’s approval, swallowed
living specimens of the _Cysticercus bovis_, the intentional ingestion
of beef measles is by no means a novelty. Eight or ten years back Dr
Oliver (after explaining to one of the selected victims the possible
consequences of the experiment) induced a Mahommedan syce or groom and a
Hindoo boy to swallow perfectly fresh and living beef measles. In this
way Dr Oliver successfully reared the _Tænia mediocanellata_ in India,
and he was thus enabled to fix the amount of time necessary for the
full growth of the strobila. Many other persons have displayed an equal
amount of zeal in the cause of helminthology, by partaking of the larvæ
or germs of other parasites. Thus, at the risk of repetition, I may
state that Möller many years ago swallowed the slender-necked hydatid
(_Cysticercus tenuicollis_) in the hope of infesting himself with _Tænia
marginata_. Several persons have defiantly swallowed trichinised flesh.
Professor Leuckart and some of his pupils also courageously swallowed
the eggs of _Oxyurides_, and they had the infinite satisfaction of
noticing the young worms in their fæcal discharges some fifteen days
afterwards. Dr Crisp ate part of the cooked flesh of an animal that had
died of cattle plague, and I myself partook of moderately cooked meat
which I knew to be swarming with psorosperms. These obscure organisms
were by some persons considered to be either a cause or product of
the rinderpest. They will be noticed in my account of the Protozoal
parasites.
For the purpose of advancing science and the welfare of the people,
there are scores of persons always to be found ready to make personal
sacrifices of the kind undertaken by Drs Ragni, Martini, and Gemelli.
Unfortunately for English science there are not wanting people in
this country who are prepared to threaten with fines and imprisonment
any _savant_ who may think it desirable to perform a similar set of
feeding experiments on animals. Invaluable for good as our experimental
investigations have already been, it would seem as if it were the
deliberate aim of these sentimental obstructives to put a stop to the
acquisition of all useful knowledge in the future.
In reference to the rate of growth of tapeworms, Professor Perroncito’s
determinations are useful, inasmuch as they verify certain ascertained
facts with precision and confirm the general conclusion that had been
drawn by practical helminthologists from various sources of information.
In regard to the number of proglottides proper to a sexually mature
tapeworm, the circumstance that Perroncito’s calculation was made
without the head and a portion of the neck of the worm being present
shows that it cannot be relied on absolutely; nevertheless, as far
as it goes, it tends to confirm what Leuckart had long previously
stated. I have possessed myself of upwards of thirty perfect beef
tapeworms expelled from my patients, and in some of the specimens it
was noticed that the segmentation-rings in the region of the neck were
far more crowded together than they were in others. I also possess a
perfect _Tænia mediocanellata_, removed post mortem. Though the rate
of growth may be the same from day to day, yet experience has shown
that the number of proglottides actually cast off varies exceedingly.
Küchenmeister’s estimate of the average number agrees in the main with
what we have ourselves observed (five to twenty daily); and here again
Perroncito’s investigations serve to verify the general correctness of
our previous determinations.
To return to Pellizzari’s researches, one of the most important
questions is that which relates to the prevalence of tapeworm. In this
connection he first brings forward some very interesting and instructive
data that had been previously communicated to the Medico-Physical
Academy of Florence by Professor Marchi. On the occasion referred to
Marchi had stated that, out of thirty-five Tæniæ which he had examined,
only one belonged to the species known as _Tænia solium_; all the other
thirty-four being of the unarmed type, or _Tænia mediocanellata_.
Reflecting on this striking fact, and also on the circumstance that
he had in vain begged his colleagues to send him specimens of _Tænia
solium_, Marchi seems to have missed the very palpable explanation of
this otherwise strange phenomenon. “How does it happen,” exclaimed
Marchi, “that, notwithstanding the occurrence of 13,000 kilogrammes of
the flesh of measled hogs in the public butcheries, I have seen but one
specimen of _Tænia solium_, whilst thirty-four cannot have originated
from the pig?” “The wherefore is obvious enough,” replies Pellizzari,
“because our hygienic regulations demand that the flesh of the hogs
be raised to a temperature of 60° Cent. (140° Fahr.);” and he then
himself immediately proceeds to ask another question, namely, as to
how it happens that the _Tænia solium_ is so frequently seen in other
places. To his own question Pellizzari responds by remarking--(1)
that there are not so many precautions (of a sanitary kind) taken in
other places; and (2) that the people elsewhere consume more slightly
salted or uncooked meat, as sausages and so forth (_come salame giovane,
salciccia e via dicendo_). Pellizzari, having explained that Marchi’s
thirty-four tapeworms must all have arisen from the consumption of
the Cysticercus of the ox, then goes on to speak of the prevalence of
tapeworm in Florence, even in little children. This last-named feature,
he says, is due to the circumstance that raw meat is frequently employed
as a restorative (_come cura ricostituente_). “Thirty years ago,”
remarks Professor Pellizzari, “it was just as difficult to find a single
_Tænia mediocanellata_ as it is now easy to find a great number of these
worms; and all because it is nowadays customary to eat the flesh of
the ox either insufficiently cooked or raw. This absolute inversion of
the facts of the case affords proof of the correctness of the position
sustained by me, to the effect that the cooking of meat up to the degree
of temperature necessary for ebullition ensures the destruction of the
Cysticerci.” Notwithstanding this statement of his own, Pellizzari
thinks that the interference of inspectors may be pushed too far, and
thus serve to bring about the very disasters which it should be their
supreme object to prevent. Thus, he argues against the suggestions of
those who would entirely prevent the sale of measly meat, and who would
only permit, as obtains in the province of Modena, the melting down of
the fat of hogs. Very strict measures of this sort would, as he says,
constitute a radical means of entirely stamping out _Tænia_, but he also
very judiciously reminds the sanitarian (_igienista_) that “such a step
would be a serious thing for the tradesman, bringing injury not only
to the municipal administration, but also proving an encouragement to
smuggling. In this way the public health would sustain worse injury by
the inducement held out to the owners of infected animals to slaughter
them in secret butcheries, thus little by little withdrawing the meat
from the superintendence of the public officials. By the adoption of
fraudulent measures there would be a daily consumption of diseased
meat; and thus also, while the public administration would suffer loss,
the public health, on the other hand, would gain nothing.” In effect
Pellizzari says, if we advise the employment of more severe and radical
measures than those already in vogue in Florence, we should overburden
the tradesman, almost compel him to defraud the exchequer by smuggling,
and greatly injure the public health.
The facts and explanations advanced by Italian writers regarding the
causes of the endemic prevalence of tapeworm, are in perfect harmony
with those previously obtained from other sources. Respecting these
causes there is much that is both new and interesting. The eighth
annual report of the sanitary commissioner of the Government of India
had already made us acquainted with the fact that during the year 1869,
out of 13,818 head of cattle slaughtered in the stations of the Upper
Punjab, 768 beasts were found to be infected with measle-cysts. This,
as I have remarked (Tommasi’s edit., p. 54), “affords a rate of 5·55
per cent., being a considerable diminution of the proportion observed
in 1868, when the percentage gave a total of 6·12. The reduction was,
without doubt, due to the vigilance and enlightenment of the army meat
inspectors. The prevalence, however, of tapeworm does not bear relation
to the number of animals infested with Cysticerci so much as to the
actual number of Cysticerci developed in infected animals. I have
frequently pointed out the inadvisability of condemning and burying
the carcases of measly oxen, whether there be few or many Cysticerci
present, and I have stated, on trustworthy evidence, that even the
presence of a few Cysticerci is deemed by some inspectors a sufficient
reason for rejecting the entire animal. Such a waste should never be
allowed. In regard to the numbers of ox-measles present in particular
instances, I have elsewhere adduced some remarkable facts communicated
to me by Dr Joseph Fleming, of the Indian Army Medical Staff. None of
my experimental animals, though fed with scores of ripe proglottides,
yielded such an abundance of Cysticerci as Dr Fleming encountered in
Punjab cattle. In one pound weight of the psoas muscles Fleming counted
no less than 300 Cysticerci.” From this it follows that the flesh of a
largely infested animal is capable, under the circumstances of ration
distribution and imperfect cooking, of originating numerous tapeworms.
Not many years back the leading medical journal of this country
challenged me to produce evidence as to the injuriousness of beef and
mutton from Cysticerci. The writer stated in his article that I had
“failed to produce a single specimen of beef or mutton measles” which
had not resulted from experiments conducted “at the Royal Veterinary
College;” and he said, further, “that butchers, fleshers, and
veterinarians were practically right in refusing to adopt the opinion of
Dr Cobbold, that measled beef or mutton is produced to any great extent”
independently. How palpably I endured a species of unjust reproach for
being somewhat in advance of the knowledge current at the time may be
gathered from the voluminous evidence which has since cropped up from
various parts of the world. It was, indeed, mainly through experiments
conducted at the Royal Veterinary College, and reported in the ‘Lancet,’
that professional men in India first became acquainted with the
possibility of finding Cysticerci in beef.
The statements of Dr Joseph Fleming, who was one of the foremost in
discovering cystic disease in cattle, have since received abundant
confirmation. The Indian Government Reports given in the February
issue of the ‘Madras Monthly Journal of Medical Science’ for 1873 are
especially instructive. Referring to the prevalence of Cysticercus in
the ration beef at Jullundur, in the Punjab, the Inspector General
(India Medical Department) reports as follows:
“Cysticercus was first noticed here in the beef tendered at the Royal
Artillery ration stand in May, 1868. For some two years previous to this
date condemnations of cyst-infected meat had been frequent at Peshawur,
Rawul Pindee, Meean Meer and several other stations in the upper part of
the Punjab, and here I had often detected the parasite in meat exposed
for sale in the bazaars, but no trace of it had been observed in the
Commissariat beef, either by myself or any other medical officer who had
preceded me.
“From May, 1868, to November, 1869, ‘cyst’ was more or less frequently
found both at the Artillery and 92nd Highlanders’ ration stands; but
since the latter date it has almost entirely disappeared.
“The following table shows the quantity of meat destroyed on this
account during 1868 and 1869:
+--------+-----------+------------------+---------------+
| Years. | Months. | Number of cattle | Weight of meat|
| | | infected. | destroyed. |
+--------+-----------+------------------+---------------+
| { | May | 4 | 412 lbs. |
| { | June | 1 | 77 " |
| { | September | 1 | 130 " |
| 1868 { | October | 10 | 1,763 " |
| { | November | 14 | 2,010 " |
| { | December | 12 | 1,785 " |
+--------+-----------+------------------+---------------+
| { | January | 21 | 4,062 lbs. |
| { | February | 16 | 2,341 " |
| { | March | 14 | 2,209 " |
| { | April | 5 | 856 " |
| 1869 { | May | 2 | 220 " |
| { | June | 1 | 122 " |
| { | July | 1 | 194 " |
| { | August | 3 | 464 " |
| { | September | 2 | 218 " |
| { | October | 4 | 615 " |
| +-----------+------------------+---------------+
| | Total | 111 | 17,478 lbs. |
+--------+-----------+------------------+---------------+
“The whole of this meat was otherwise well fed and of excellent quality.
The waste of so much good food led me to make inquiries; 1st, as to the
sources from which the cattle obtained the Tænia ova, and the best means
for preventing their infection; and 2ndly, as to whether or not any evil
results followed the consumption of this meat when properly cooked.
“From information obtained from the Commissariat Officer I found--1st.
That the infected cattle had been purchased by native dealers from
various parts of the district, not from any particular locality. 2ndly.
That when brought in they were lean, and on an average required from two
to three months’ feeding at the Commissariat cattle yards before they
were fit for the shambles. 3rdly. That their food consisted of the grass
they could pick up on the grazing grounds of cantonments, supplemented
by such an allowance of grain and _bhoosâ_ as their condition required.
“They were supposed to be watered at a trough with water drawn from a
well, but on closely inquiring as to this, it transpired that they very
frequently were taken to a large dirty tank near the yard for their
water. The question which occurred to me was, were the cattle infected
before their purchase by the Commissariat, or was there anything in
their feeding to account for it after purchase? I am inclined to the
latter opinion for several reasons, thus:--In the large number of
the diseased cattle, the Cysticerci were of remarkably small size;
many of them having no capsules, except such as were formed by the
surrounding structures, and not being more than 1/8 to 1/4 of an inch
in diameter. Although the dry food given to the cattle was doubtless
good, still much of the water they got during 1868 was probably filthy.
The tank previously referred to was situated close to the huts of the
camel drivers. These men are all Mussulmans from Cabul, Peshawur, or
thereabouts, and many of them are infected with _Tænia mediocanellata_.
Human filth was often to be seen on the banks of the tank, and
microscopic examination of mud and stagnant water taken from the margin
exhibited _Tænia_ ova.
“The conditions above shown must have been eminently favorable to
keeping up a constant supply of ova, and the fact that Cysticercus
entirely disappeared from amongst the cattle a few months after me
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