The well-known fact that, in respect of their habits, the pouched
mammals epitomise, as it were, the non-marsupial quadrupeds, would
naturally lead us to look for a repetition of corresponding type-forms
of entozoa as guests within their bodies. Speaking generally, the
inference is correct; but very few of the entozoa hitherto found
in marsupials correspond, as species, with those infesting man and
non-pouched mammalia. A noteworthy exception occurs in the case of
the common liver-fluke, which is abundant in the great kangaroo
(_Macropus major_). This fact was well known to Bremser and all the
older helminthologists, and it has since been confirmed by numerous
observers resident in Australia. The late Dr Rowe, an acute observer
and successful stock-breeder, who wrote chiefly in connection with the
sanitary bearings of parasitism, remarked that “the native animals of
Australia are much infested with internal parasites. Some of those now
found in the kangaroo and the smaller marsupials may have been derived
from our domestic animals; but tapeworms and other internal parasites
have been met with in animals occupying regions wholly unsettled.”
Precisely so. That is just what we should expect. The Australian
indigenous mammals have their own entozoa as a matter of course, and, in
addition, they have contracted a few species from the domestic animals
introduced into the country. On the whole, however, it cannot be said
that the parasites of marsupials are of much practical consequence
to agriculturists, since, with the exception of flukes, and probably
hydatids, the Australian marsupials do not appear to harbor any entozoa
that are likely to prove injurious to man and his domestic companions.
The amount of fluke-germ distribution by kangaroos must be infinitesimal
as compared with that proceeding from sheep and other kinds of “stock;”
therefore on the score of parasitism alone it is not desirable to hasten
the slaughter of kangaroos. From the scientific standpoint, it is to be
regretted that the naturalists of New South Wales and other colonies
have done so little towards defining the various species of marsupial
entozoa. Mr Krefft, in his interesting brochure on Australian entozoa,
describes a few tapeworms, and also points to several round worms which
may be new to science, but with the exception of the common fluke no
trematode appears to have been encountered by himself or Mr Masters
in the various marsupials which they examined in the neighbourhood of
Sydney and Queensland. Dr Bancroft, of Brisbane, has placed in my hands
a small collection of entozoa, several of which have been obtained from
marsupials, but their identification remains partly in abeyance.
Besides the liver-fluke, the only marsupial trematodes at present
fairly described appear to be _Hemistoma alatum_, and two species of
_Rhopalophorus_ (_R. coronatus_ and _R. horridus_). All of these were
obtained by Natterer from the opossums of tropical America. One of these
flukes was described at some length by Rudolphi, who called the species
_Distoma coronatum_, and gave its length as varying from two to four
lines. Diesing, in one of his best illustrated monographs, has shown
that the opossums in question are infested by two distinct species of
fluke, which must be generically separated from the distomes. These
singular _Rhopalophori_ are furnished with a pair of armed retractile
proboscides (Bohrüsseln), which must form powerful organs of anchorage.
The worms are found attached to the walls of the stomach and small
intestines.
The tapeworms of marsupials are more numerous than flukes. Thus, we have
Rudolphi’s _Tænia festiva_, eight to ten inches in length, occupying the
gall-bladder and hepatic duct of _Macropus giganteus_. Dr Bancroft’s
collection contains two almost perfect examples of a tapeworm which
he procured from a small streaked kangaroo (_Halmaturus Derbyanus_).
These I have identified as _T. festiva_. In this worm the reproductive
papillæ, not hitherto observed, are biserially arranged. Fragments of a
tapeworm (_T. didelphidis_) are preserved in the Vienna Museum, taken
from the intestines of the American _Didelphis murina_. From different
species of wallaby (_Halmaturus_) Mr Gerard Krefft has given more or
less complete descriptions of two tapeworms (_Tænia fimbriata_, and _T.
Mastersii_), and a probable Bothriocephalus (_B. marginatus_). I am not
in a position to pronounce upon the distinctness of these Australian
_Tæniæ_; but I may observe that Krefft’s _T. fimbriata_ comes very near
to another species which Dr Bancroft has given me. The Brisbane _savant_
obtained the worm from a koala (_Phascolarctos cinereus_). Provisionally
I call this species _Tænia geophiloides_, in allusion to its general
resemblance to a long millipede. The single, perfect strobile, with
the head attached, measures thirteen inches in length. Prof. Leidy has
furnished a description of another tapeworm (_T. bipapillosa_) from a
wombat (_Phascolomys_), and Mr Krefft has described yet another species
obtained from the common vulpine opossum (_Phalangista vulpina_). The
single example in Krefft’s possession measures four inches in length.
He has named it _Tænia phalangistæ_. Some of the American opossums
(_Didelphys brachyura_, and _D. quica_) have been found to harbor a
species of ligula (_L. reptans_, Diesing) in the sexually-immature
state. Lastly, I find in Bancroft’s collection several tapeworms
obtained from that small and interesting monotreme marsupial commonly
known as the Australian hedgehog, echidna, or porcupine ant-eater of
the colonists (_Tachyglossus setosus_). The strobiles, which are nearly
perfect, average three inches in length, and are made of very narrow
and closely-set proglottides. This species is evidently new to science,
and as such I propose to call it _Tænia phoptica_, in allusion to its
thick-set appearance and its consequent burdensome character to the
bearer. The largest proglottides measure fully 3/8″ in width. There can
be little doubt that the presence of any considerable number of such
comparatively large tapeworms must seriously incommode, if they do not
actually prove fatal to their unfortunate hosts.
So far as regards mere variety of species, the nematode fauna of
marsupials is probably far in excess of that of the trematodes and
cestodes. I cannot therefore do much more than enumerate the species.
The Hunterian Museum of the Royal College of Surgeons contains the
original “worms found alive within the capsular ligaments of the
knee-joint of a kangaroo,” which have been indicated as _Filariæ
macropodis gigantei_. It would, in my opinion, be far better to call
the worm, after its discoverer, Webster’s filaria (_F. Websteri_).
Dr Bancroft has likewise encountered this same parasite in the great
kangaroo. From the abdominal cavity of a wallaby Leidy has also obtained
a filaria (_F. spelæa_). The American opossums (_Didelphys_) are much
infested by _Ascaris tentaculata_, which is found in the cæcum, and many
of them also harbor a small whipworm (_Trichocephalus minutus_). Another
tolerably abundant nematode (_Physaloptera turgida_) was obtained by
Natterer from the stomach of _Didelphys azaræ_, _D. myosurus_, and _D.
cancrivora_. The only other nematode mentioned in Diesing’s ‘Systema’
is _Aspidocephalus scoleciformis_. This is found in _D. murina_, and
_D. domestica_. From the opossum of the United States (_D. virginiana_)
Prof. Leidy has also obtained _Asc. tentaculata_, _Trichocephalus
minutus_, and _Physaloptera_ (Spiroptera) _turgida_. According to Molin
there are grounds for separating some of these stomach-worms into
distinct species. Thus, he has recognised the examples found by Natterer
in _Didelphys myosurus_ as belonging to the genus _Histiocephalus_, as
emended by himself. If the separation be allowed, then we must add to
the list Molin’s _Histiocephalus subulatus_. From Bancroft’s collection
I am certainly in possession of two distinct kinds of nematode taken
from the stomach of _Halmaturus Derbyensis_. I have also two species of
nematode from _Macropus giganteus_. Their identification, however, is a
matter for future consideration. Lastly, as regards the acanthocephalous
parasites, only one species appears to have been described. This worm
(_Echinorhynchus microcephalus_) was obtained by Olfers in Brazil,
from the intestines of _Didelphus philander_. It also occurs in _D.
virginiana_. Being a tolerably large species, that is to say 3″ in
length, it seems surprising that it has not been found in the American
opossums generally.
BIBLIOGRAPHY (No. 56).--_Cobbold_ (see Rowe). _Diesing_, ‘Syst.,’ l. c.,
p. 519; also monogr. ‘Binnenwürmen’ (l. c., Bibl. No. 55).--_Krefft,
G._, ‘Australian Entozoa’ (l. c., Bibl. No. 55).--_Leidy_, ‘Proc.
Philad. Acad.,’ 1856.--_Idem_, “Tapeworm from the Wombat,” _ibid._,
1875, p. 6.--_Molin_, “Una monogr. del genere Physaloptera,” p.
10, “Una monogr. del gen. Dispharagus,” and “Una monogr. del gen.
Histiocephalus,” p. 37, aus dem xxxix Bd., d. ‘Sitz. d. m.-nat. Cl.
d. k. Akad. der Wissensch.,’ s. 479-507 und s. 637-672, 1860.--_Rowe,
J._, “Parasitism in Australia” (in which the author sought to benefit
stock-owners by utilising, prophylactically, my published opinions),
repr. from the ‘Melbourne Leader’ in the ‘Veterinarian,’ May,
1874.--_Rudolphi_ (in ref. to _Dist. coronatum_), ‘Synops.,’ p. 116
and 686.--_Webster_ (respecting his “Filaria,” see), ‘Catalogue of the
Hunterian Collection of Entozoa,’ p. 7, prep. 49, 1866; also the old
‘Catal. of the Museum Roy. Coll. Surg.’ (by Owen), part iv, fasc. i, p.
37, No. 170; also Diesing’s ‘System,’ p. 280, and Froriep’s ‘Notizen,’
Bd. xlii, s. 328.
SECTION II.
To give an air of completeness to this treatise, I shall devote the few
pages remaining at my disposal to a brief summary of the general facts
of parasitism as witnessed in birds, reptiles, fishes, and evertebrated
animals. For details I must refer to the separate original works and
memoirs quoted in the appended bibliographies.
PART I (AVES).
A prodigious number of entozoa are known to infest birds. So far from
birds being less victimised than mammals, the contrary is the case.
Every now and then avian epizoötics, due to parasites, sweep off
hundreds of these attractive hosts, and in some cases even nestlings
are not secure from entozoal invasion. It might be supposed that
predacious birds would be more liable to invasion than the graminivorous
species. Such is not the case. The eagles, hawks, vultures, and owls
certainly harbor a great variety of helminths, but as much may be said
of the grain-feeding game birds, and still more of the water birds.
Pheasants and land-fowl, grouse and partridges, are largely infested;
whilst, of water-fowl, herons and plovers, rails and snipe, ducks and
geese, cormorants and divers, gulls and awks, play the rôle of host to
a practically infinite variety of parasitic guests. The presence of
the worm-guests does not imply any previously diseased condition of
the host. Shoot any water bird, say an oyster catcher (_Hæmatopus_),
or, still better, a grebe (_Podiceps_), and then carefully examine its
intestinal contents. You will probably find in its interior flukes and
round worms, tapeworms and Echinorhynchi. Capture and examine a frog or
a salamander. The result is the same, except that the cestodes would
probably be absent. As for fishes, if entozoa be a proof of cachexia,
then it follows that the normal condition of all piscine hosts is a
diseased state. Examine any tolerably well-grown salmon, trout, pike,
perch, roach, chub, carp, or barbel, and probably any one of them will
contain at least three different kinds of parasites, each of which will
be present in more or less considerable numbers. From what is stated
above it would be obviously futile to attempt even an enumeration of
the species of avian entozoa--a remark which applies almost equally to
the other groups of hosts that remain for consideration. Confining our
attention to a few of the more noteworthy facts, I may observe that
we have no very trustworthy data respecting the power for mischief
possessed by flukes. From what we know of their destructiveness in man
and certain other mammals, it would be hazardous to pronounce them
harmless. Scientifically, they furnish particulars of great interest.
One of the most striking facts of recent study relates to Zeller’s
discovery that the little cercariæ (_C. exfoliata_) which are contained
in a peculiar sporocyst (_Leucochloridium paradoxum_), infesting the
tentacles of a snail (_Succinea amphibia_), are in reality larval forms
of a fluke (_Distoma macrostomum_) which resides in the intestinal canal
of warblers (_Sylviadæ_). By experiment Dr Zeller reared the _Distoma_
in question in the intestines of whitethroats (_Curruca garrula_), in
blackcaps (_C. atricapilla_), and in wagtails (_Motacilla_). Six days
after transference the Cercariæ acquired sexual maturity. The odd thing
is, that as the sporocystic _Leucochloridia_ resemble insect larvæ, they
are attacked and swallowed by the birds under delusion. It is a curious
example of mimetism in favour of the fluke’s welfare. To this and other
equally brilliant scientific results helminthologists were gradually
led up by the earlier researches of Steenstrup and Van Beneden. As
remarked in my ‘Entozoa,’ ever since Steenstrup’s discovery of the fact
that Cercariæ found in the bodies of water-snails were larval flukes,
a peculiar interest has attached itself to this subject. Not only were
the conclusions which he elicited novel in themselves, but they formed
a basis for the enunciation of that interesting “law of alternate
generation” with which the famous Danish naturalist’s name will ever
remain associated. In all essential particulars Steenstrup’s statements
have been verified.
By way of illustrating the phases of development through which the
distomes pass I cannot do better than recapitulate in an abridged
form the account I have previously given of _Distoma_ (_Echinostoma_)
_militare_ of the snipe and curlew. This account is based on the
investigations of Van Beneden, Von Siebold, and Pagenstecher. I
regret that it is out of my power to reproduce the illustrations
that have already appeared on this head in my introductory treatise
(see ‘Entozoa,’ figs. 5 to 9 inclusive). Our _Echinostoma militare_
produces oval-shaped eggs, which give birth to a free ciliated embryo,
and this embryo produces a sporocyst or scolex by internal budding.
When the sporocyst separates itself from the embryo it presents a
very simple appearance, but showing already a cæcal digestive tube.
The tail end is fissured, indicating an early stage of formation of
caudal appendages. In the next stage we have a well-developed head and
body, the tail becoming strongly pronounced. Limb-like caudal lobes
project on either side, and an oral sucker makes its appearance in
front. This sucker communicates with the œsophageal bulb and passes
directly into the digestive cæcum, which contains a variable number
of rounded particles. At this stage, also, incompletely developed
Cercariæ may be seen in the perivisceral cavity. These Cercariæ are
at first shapeless organisms, but after passing through a series of
gradations they ultimately assume a definite form, which, in many
cases, is sufficiently distinctive to enable us to refer the Cercariæ
to particular species of _Distoma_. The older writers regarded many
of the cercarians as adult flukes. In the early state these larvæ are
furnished with tails. They may be seen lodged within the cavity of the
body of the sporocysts, being twisted and folded in various attitudes.
The Cercariæ not only exhibit a cephalic and ventral sucker, but also a
dark forked line representing the digestive system. At a still further
stage other structures come into view, until the perfect Cercaria
displays an oral sucker, a pharyngeal bulb, an œsophagus, two alimentary
cæca, a ventral sucker, a water-vascular system consisting of two main
excretory ducts, and a contractile vesicle, by means of which the ducts
communicate with the external surface. The tail is conspicuous and
furnished with a fringe. The alimentary organs conform to the general
trematode type, but before passing into the sexually-mature condition
other changes are undergone. The Cercariæ part with their tails, and
subsequently they encyst themselves on or within the surface of the
body of some mollusk. Their pupa condition is thus arrived at. The pupa
itself differs from the cercaria in presenting a double crown of hooks
surrounding the head, but the other organs correspond with those already
described. According to Van Beneden the hooks make their appearance
immediately after encystation. In this condition it is next transferred
to the intestine of some higher animal, and in this final situation it
gradually acquires all those organs the possession of which will entitle
it to be called a sexually-mature or adult distome. In the immature
fluke we may now discern the mouth, the buccal or cephalic sucker, the
pharyngeal bulb, the œsophagus, the digestive cæca, the coronal spines,
the contractile vesicle, the aquiferous system of vessels, the matrices
of the yelk-forming glands, and also a central mass of cellules, from
which all the other reproductive organs will in due time be developed.
In the adult _Echinostoma militare_ the upper third of the body is
clothed with little spines. Taking this example as illustrative of the
ordinary mode of fluke development we find that a change of hosts is
necessary, and that in the intermediate state they occupy the bodies
of mollusks. Thus, for the continuation of the species, there must
needs be a contemporaneity of vertebrate and evertebrate hosts. Surely
no reasonable person can ascribe this concurrence to merely fortuitous
circumstances. In this connection I may remark that Villot, in his
account of the migrations of the trematodes, states that the cercarian
forms of _Distoma leptosomum_ and _D. brachysomum_ of _Tringa alpina_
occur in _Scrobicularia_ and _Anthura_. These parasites are also found
encysted in the gizzard of _Tringa_.
[Illustration: FIG. 72.--Head of _Tænia paradoxa_. _a_, Proboscis
retracted; _b_, end of the rostellum expanded. Highly magnified. From an
oyster-catcher (_Hæmatopus ostralegus_). Original.]
The tapeworms of birds are undoubtedly injurious to their bearers. All
the worms appear to be armed with cephalic hooks; at least, such is the
case with the species described by Krabbe, who has supplied figures
of the hooks drawn to a scale. Dr Krabbe’s beautiful monograph is a
perfect model of its kind. In the accompanying figure the hooks have
fallen (Fig. 72). On account of the frequency of their occurrence,
some persons have supposed that tapeworms are not injurious to their
hosts, forgetting that it is not the mere fact of the existence of
tapeworms, but their excessive numbers during particular seasons that
give rise to avian epizoötics. The same rule holds good with other
parasites. Of course, in fledgelings, as also obtains in yearlings
amongst our domesticated animals, a very few parasites are sufficient
to prove destructive to the bearer. Thus, as regards the so-called
“grouse-disease,” during one season it may be due to tapeworms, during
another to strongyles, during a third to excessive abundance of both
these parasites. Unfortunately, other avian epizoötics, not necessarily
due to parasites of any kind, may be mistaken for helminthic epizoöty.
The same thing happens amongst quadrupeds. We have, for example,
parasitic equine epizoötic outbreaks, and likewise non-helminthic
equine epidemics (as in the case of the Egyptian horse plague of 1876).
The true nature of any epizoöty can only be determined by competent
investigation. That was well shown in the grouse epidemic of 1872. In
that epizoöty the greater number of the birds succumbed to the injuries
produced by a nematode worm (_Strongylus pergracilis_, Fig. 73), but,
without doubt, the occasional presence of numerous tapeworms (_Tænia
calva_) hastened the consequent fatality. The following table, giving
the results of examination of twelve diseased grouse from the Earl of
Cawdor’s estate, will show how inconspicuous a part tapeworms played in
the epidemic of 1872. For further details I must refer to my brochure
on the ‘Grouse Disease,’ and to some other memoirs quoted in the
bibliography below.
+----------+-----------+---------------+-----------+----------------+
| No. of | Condition | State of | Tapeworms | Strongyles |
| specimen.| of bird. | viscera. | present. | present. |
+----------+-----------+---------------+-----------+----------------+
| 1 | Good | Full | None | Abundant. |
| 2 | Emaciated | Putrid | Two | Very numerous. |
| 3 | Good | Full | None | Abundant. |
| 4 | " | " | " | " |
| 5 | " | " | One | " |
| 6 | " | Shrunken | Two | Very numerous. |
| 7 | Emaciated | Much shrunken | None | " |
| 8 | Thin | Shrunken | " | " |
| 9 | " | " | " | " |
| 10 | Emaciated | Distended | Man | " |
| 11 | Thin | Rather full | Several | Abundant. |
| 12 | " | " | None | Very numerous. |
+----------+-----------+---------------+-----------+----------------+
[Illustration: FIG. 73.--_Strongylus pergracilis._ _a_, Head and neck;
_b_, _c_, _d_, _e_, tail of the male in various positions; _f_, tail of
the female; _g_, section showing termination of the oviducts; _h_, three
eggs. Highly magnified. Original.]
I have said that tapeworms prove fatal to young birds, even to
nestlings. A notable instance of this is recorded by Mr Eames.
The parasites were examples of _Tænia angulata_. Apart from the
epidemiological aspects of the subject, it is not uninstructive to
notice the variety of helminths that infest the common fowl and game
birds. Accordingly, I append a similar but more extended list than that
previously given in the supplement to my introductory treatise:
Key to Column Headings:
A = Common fowl. E = Red Grouse.
B = Pheasant. F = Grey Partridge.
C = Capercaillie. G = Red Partridge.
D = Black Grouse. H = Quail.
+----------------------------------+---+---+---+---+---+---+---+---+
| Entozoa of game birds and the | A | B | C | D | E | F | G | H |
| common fowl. | | | | | | | | |
+----------------------------------+---+---+---+---+---+---+---+---+
|_Monostoma verrucosum_, Zeder | * | | | | | | | |
|_Distoma oxycephalum_, Rudolphi | * | | | | | | | |
| " _ovatum_, Rudolphi | * | | | | | | | |
| " _lineare_, Zeder | * | | | | | | | |
| " _dilatatum_, Miram | * | | | | | | | |
| " _fuscatum_, Rudolphi | | | | | | | | * |
|_Filaria Mansoni_, Cobbold | * | | | | | | | |
|_Ascaris vesicularis_, Froelich | * | * | * | | * | * | | * |
| " _gibbosa_, Rudolphi | * | | | | | | | |
| " _inflexa_, Rudolphi | * | | * | | | | | |
| " _compar_, Schrank | | | | * | * | * | | * |
|_Spiroptera hamulosa_, Diesing | * | | | | | | | |
| " _helicina_, Molin | | | | | | | * | |
|_Dispharagus nasutus_, Dujardin | * | | | | | | | |
| " _spiralis_, Molin | * | | | | | | | |
|_Strongylus pergracilis_, Cobbold | | | | | * | | | |
|_Sclerostoma syngamus_, Diesing | * | * | | | | * | | |
|_Trichosoma longicolle_, Rudolphi | | * | * | * | | * | | |
|_Tænia malleus_, Goeze | * | | | | | | | |
| " _microps_, Diesing | | | * | * | | | | |
| " _exilis_, Dujardin | * | | | | | | | |
| " _calva_, Baird | | | | | * | | | |
| " _linea_, Goeze | | | | | * | * | | * |
| " _infundibuliformis_, Goeze | * | * | | | | | | |
|_Ligula reptans_, Diesing | | | * | | | | | |
+----------------------------------+---+---+---+---+---+---+---+---+
In regard to this list I can only afford space to remark that several
of the species are possibly mere varieties. Some of the worms are of
great interest. It occasionally happens that _Distoma ovatum_ is found
in the albumen of the fowl’s egg, and it is even more common to obtain
_Ascaris inflexa_ from the same situation. For a recent example I am
indebted to Dr Walker, of Peterborough. _Spiroptera helicina_ resides
in the feet, occasioning enlargement of the joints and consequent
distress to the bearer. Probably the most important in the list is my
_Strongylus pergracilis_. Here I may mention that on the 10th of April,
1878, I received a letter from Dr Manson, of Amoy, announcing his
acquaintance with a filaria infesting the eye of the fowl. On the 9th of
May I also received from Dr Manson the head of a bird showing examples
of the worm. As the species is new to science I have proposed to call
it _Filaria Mansoni_, after the discoverer. The male is 5/8″ and the
female 3/4″ in length. Of the injurious nematodes, giving rise to avian
epizoöty, probably one of the most destructive is _Ascaris maculosa_
infesting pigeons. On the 9th of October, 1873, I received a letter from
Dr J. Alexander Macdonald, of Woburn, Bedfordshire, stating that he
had forwarded to me a pigeon which had been found dead on the previous
morning. It seems that the owner of the bird had erected a large
pigeon-house, and had imported a number of Antwerp smerles, these birds
all continuing in a perfect state of health until about a week before
the above-mentioned date, when, to use Dr Macdonald’s words “first one
and then another was attacked, and so on, until four or five of the
pigeons had died after a few hours’ illness.” The suddenness of these
attacks not unnaturally suggested poisoning; and, accordingly, says my
informant, the owner “had the curiosity to open one of the birds, when,
to his astonishment, he found the intestines stuffed with worms.” Two
days later I received a letter from Dr Macdonald, stating that several
others of the flock had died, and it further appeared to him probable
that the daily list of sick and dying would continue to increase. On
the 14th of the month three more of the birds were dead. On the 4th of
the following November, the same correspondent obligingly informed me
that the epidemic had been “at last mastered.” It seems that altogether
twelve birds had perished. On the 9th of October one of the birds was
carefully examined by me, and the results were so interesting that I am
constrained to give a few of the particulars originally communicated
to the Zoological Society. As stated in my paper, the whole intestinal
tract of the dead bird was crowded with these ascarides. The small
intestine was inflamed throughout, and showed several large ulcerated
patches; nevertheless, there were no traces of emaciation. From this
it was evident that the parasites had grown quickly, the malady having
a correspondingly rapid formation. The distribution of the parasites
was curious. One specimen, two inches long, reached from the crop to
the proventriculus. The cavities of this organ and of the gizzard were
crammed with worms completely blocking the passage. Three of the worms
had also placed themselves within the pyloric opening, their bodies
partly lodging within the duodenum. The duodenum itself was crowded with
worms, their numbers somewhat decreasing downwards. I removed thirty-six
worms from the œsophagus, proventriculus, and stomach, besides 166
others from the intestinal canal, thus obtaining a total of no less than
202 nematodes from this small host. Considering the large size of these
entozoa, the extent of infection must be pronounced remarkable. The
largest females measured 2-1/2″ in length. One of the most interesting
facts--serving to exemplify a well-known habit of lumbricoid worms
generally--consisted in the circumstance that two of the parasites had
succeeded in perforating the horny lining membrane of the gizzard. The
injuries had been accomplished during the life of the host, for the
walls of the gizzard were inflamed opposite the perforations. There
was a little half digested food within the stomach, the _débris_ of
which, when placed under the microscope, showed several ova. There
were no free embryos, neither had the development of the freed eggs
proceeded beyond yelk-segmentation. Free eggs were also found both in
the small and large intestine. The eggs measured about 1/360″ by 1/700″
in diameter. Referring to my paper for further anatomical details, I
can only add that, despite these facts, the ascarides in question do
not appear to be a very frequent source of epizoöty. It was remarked
by Dujardin that Heister, at Rostok, and Gebauer, at Breslau, found
this parasite abundant at the beginning of the eighteenth century; but,
according to examinations conducted at Vienna, the worm was found in
the common pigeon in only eleven instances out of 245, and thrice only
in thirty-eight examples of the ring-dove; moreover, the examination
of eighty-seven other pigeons and doves of different species yielded
entirely negative results. The Dublin helminthologist, Bellingham,
noticed the occurrence of this parasite in Ireland.
[Illustration: FIG. 74.--Tail of the male _Ascaris vesicularis_. From a
ring-necked pheasant. Original.]
Any attempt so much as to enumerate the species of nematoids infesting
birds would carry me far beyond the aim and scope of this treatise. One
of the commonest species is _Ascaris (Heterakis) vesicularis_. Many
hundreds of forms have been described by Dujardin, Diesing, Molin,
Krabbe, and other systematists, and it remains for some future laborer
to condense the facts which are dispersed throughout a very wide-spread
literature. As regards the particular species of nematoids that are
either actually known or conjectured to be injurious to birds I can only
find space to repeat some of the particulars which I have elsewhere
recorded in respect of _Sclerostoma syngamus_. In 1799 a letter from
Dr Wiesenthal, of Baltimore, U.S., was published in the ‘Medical and
Physical Journal,’ containing an account of a parasite infesting the
trachea of fowls and turkeys in America. The communication is dated May
21st, 1797, and is the first public record concerning the entozoon. Dr
Wiesenthal says: “There is a disease prevalent among the gallinaceous
poultry in this country, called the _gapes_, which destroys eight-tenths
of our fowls in many parts, and takes place in the greatest degree among
the young turkeys and chickens bred upon old-established farms. Chicks
and poults, in a few days after they are hatched, are found frequently
to open their mouths wide and gasp for breath, at the same time
frequently sneezing and attempting to swallow. At first the affection
is slight, but gradually becomes more and more oppressive, and it
ultimately destroys. Very few recover; they languish, grow dispirited,
droop, and die. It is generally known that these symptoms are occasioned
by worms in the trachea. I have seen the whole [windpipe] completely
filled with these worms, and have been astonished at the animals being
capable of respiration under such circumstances.”
Any one who has witnessed the _gapes_ will at once recognise the
accuracy of Wiesenthal’s description; and so far as the phenomena of
the disease are concerned, very little more has been added in the
numerous accounts which have since appeared. On the 1st of August, 1808,
the English naturalist, George Montagu, communicated to the Wernerian
Society a paper entitled “Account of a species of _Fasciola_ which
infests the trachea of poultry, with a mode of cure.” Montagu does not
appear to have been aware of the existence of any previous record. He
gave a scientific description of the parasite, which led to its being
noticed in the systematic works of Rudolphi, Dujardin, and Diesing,
but the best accounts of the worm are due to Von Siebold. _Sclerostoma
syngamus_ has been found in the trachea of the turkey, domestic cock,
pheasant, partridge, black stork, magpie, hooded crow, green woodpecker,
starling, and swift. In July, 1860, I obtained a fowl suffering from the
gapes, and operated upon it in the following manner:--A small portion
of wool having been dipped in chloroform and placed in front of the
nostrils the bird soon became insensible. The skin of the neck was then
divided and the trachea slit up to the extent of a quarter of an inch.
With a pair of common dissecting forceps, I removed seven Sclerostomata.
Six of these parasites were sexually united, the odd worm being a
female. After I had closed the external wound with a single thread the
bird woke out of its artificial sleep, when it soon recovered its legs,
and ran about the table vigorously. Moreover, in a very few minutes it
devoured the contents of a saucer partly filled with bread and milk. An
occasional gape was caused by an accumulation of frothy mucus within
the injured trachea, but this obstruction the bird soon got rid of by
shakes of the head and sneezing. The only subsequent inconvenience to
the bird arose from emphysematous distension of the cellular tissue of
the head and neck. This was relieved by puncture, the emphysema ceasing
to form after the external wound had healed. Some months afterwards I
destroyed the bird, and on dissecting the neck, a distinct cicatrix was
found indicating the site of the operation on the trachea. The divided
cartilaginous rings, six in number, were united only by a thin layer of
connective tissue. The female worms gave an average length of 5/8″, the
males scarcely exceeding 1/3″. The mouth is furnished with six prominent
chitinous lips. In both sexes the surface of the body is quite smooth,
but the tail of the female exhibits a tendency to fold upon itself.
The lower part of the body suddenly contracts to form a short, narrow,
mucronate, pointed tail. The male is usually found rigidly affixed by
means of a strong, membranous, sucker-like bursa, which proceeds from
the lower end of its body. In regard to the peculiar mode of union of
the sexes, it becomes an interesting point to ascertain whether there
be an actual incorporation of the substance of the copulatory organs
during or after the act of impregnation. In my specimens none of the
three pairs were organically united, and I succeeded in separating one
pair very readily. Dujardin speaks of them as being soldered together,
whilst the statements of Von Siebold are still more explicit. In
connection with this subject the latter observer makes the following
comment (‘Wiegmann’s Archiv,’ 1836, s. 106):--“The two sexes of almost
all round worms are united only at the time of copulation. The male
of _Heteroura androphora_ has also the habit of remaining connected
with its mate beyond the period of copulation; here, thus, there is
a continuous union of the sexes without a growing together; and in
_Syngamus trachealis_ there is ultimately a lasting continuity of the
sexes by means of an actual growing together.” Having confidence in Von
Siebold’s statement, I concluded that the sexual union in my specimens
had only recently been effected. Admitting this to have been the case,
one naturally asks how the mature eggs can make their escape. Clearly,
the eggs can only escape by an eventual breaking up of the body of the
parent. The eggs of _Sclerostoma syngamus_ are comparatively large,
measuring 1/250″ in length. Many of the ova contained fully formed
embryos, and in the centre of the lower third of the body of one of
them I perceived an undulating, imperfectly formed intestinal tube. By
whatever mode the young escape the shell, it is clear that they are
already sufficiently developed to undertake an active migration. A
change of hosts is probably necessary, but in the first instance they
either enter the substance of fungi or other vegetable matters, or
they bury themselves in the soil at a short distance from the surface.
In view of checking the destructive influences of this parasite, the
following methods have been recommended.
_First._ The simplest plan consists, as Dr Wiesenthal long ago pointed
out, in stripping a feather from the tube to near the narrow end of the
shaft, leaving only a few uninjured webs at the tip. The bird being
secured, the webbed extremity of the feather is introduced into the
windpipe. It is then twisted round a few times and withdrawn, when the
worms are found attached. In some instances this plan succeeds entirely.
_Secondly._ The above method is rendered more effectual when the feather
is previously steeped in some medicated solution which will destroy the
worms. Mr Bartlett employs salt for this purpose, or a weak infusion of
tobacco; and he informs me that the simple application of turpentine
to the throat externally is sufficient to kill the worms. It should be
borne in mind that the bird itself may be injuriously affected by these
drugs if they are carelessly employed.
_Thirdly._ The treatment recommended by Mr Montagu proved successful
in his hands, although the infested birds were old partridges. One of
his birds had died of suffocation; but he tells us that “change of
food and change of place, together with the infusion of rue and garlic,
instead of plain water, to drink, and chiefly hemp-seed, independent of
the green vegetables which the grass plot of the menagerie afforded,
recovered the others in a very short time.”
_Fourthly._ The plan I employed in my experiment. This is only
desirable in advanced cases, where suffocation is impending. It will
afford instant relief, as the trachea may be cleared of all parasitic
obstructions.
_Lastly._ The essential point to be observed is the total destruction
of the worms. This will help to put a stop to future epizoöties. If the
parasites are merely killed and thrown away carelessly, the eggs will
sustain no injury. Decomposition having set in, the young embryos will
sooner or later escape their shells, migrate in the soil or elsewhere,
and ultimately find their way into the air-passages of birds in the same
manner as their parents did before them.
In this place I must not omit to mention the remarkable circumstance,
quoted in my pamphlet on the grouse disease, that Prof. Wyman, of
Boston, found _Eustrongyli_ surrounding the cerebellum in seventeen out
of nineteen snake-birds or water-turkeys that had been shot in Florida.
These viviparous nematodes apparently occasion their avian bearers no
inconvenience. No doubt, as Wyman observes, their presence must be
regarded as a normal state of things: but should they occur in excessive
numbers, then we can hardly doubt the result.
As regards acanthocephalous parasites, although not so numerous as the
nematodes, it is extremely probable that they play a similar rôle.
Parasites which prove fatal to swine are scarcely likely to be harmless
in birds. On the 18th of February, 1875, I received from Sir Joseph
Hooker eleven worms for identification. Mr Charles P. Hooker, his son,
subsequently informed me by letter that he had found them in a Redwing
(_Turdus iliacus_) which he dissected in January, 1875. The worms
(_Echinorhynchus transversus_) occupied the large intestine, probably
to the number of one hundred in all. Hitherto this parasite has been
found abundantly in the blackbird, thrush, and in most of the _Turdidæ_;
but not in the redwing. It has also been obtained from the starling and
red-breast. The presence of so many of these armed parasites in one
small host could hardly fail to inflict severe injury on the bearer.
[Illustration: FIG. 75.--Head of _Eustrongylus papillosus_. Magnified.
Original.]
In concluding this section of my work I can only find space to make
a few acknowledgments. Most of the rare, new, or interesting avian
entozoa which I have examined and described have been received either
from the Zoological Gardens, or from personal friends. In particular I
may mention the collections sent to me by Mr Charles Darwin, Mr Robert
Swinhoe, Mr Charles W. Devis, Dr Murie, Dr John Anderson, and Mr Spooner
Hart, of Calcutta. A great many correspondents have contributed single
specimens, many of which I have already incidentally acknowledged
in these pages. In this place I must particularise the new species
(_Ascaris Cornelyi_) which I described from specimens sent to Mr
Sclater. This worm infests the vulturine pintado (_Numida vulturina_).
Mr Darwin’s collection contained fine examples of _Filaria horrida_ from
the American ostrich (_Rhea_). When dissecting birds at the Zoological
Society’s Menagerie, I obtained (in addition to the parasites already
mentioned) _Distoma æquale_ from the American owl (_Strix perlata_);
_Tænia multiformis_ from the night heron (_Ardea nyctocorax_); _T.
infundibuliformis_ from a horned pheasant (_Phasianus_); _T. lævis_
and _T. lanceolata_ and also _Ascaris tribothrioides_ from a dusky
duck (_Anas obscura_); _Eustrongylus papillosus_ (fig. 75) from the
larus crane (_Grus antigone_); _Trichosoma longicolle_ from the
horned pheasant, and _T. brevicolle_ from the Sandwich Island goose
(_Bernicla Sandwichensis_). This bird was also infested by _Spiroptera
crassicauda_ and _Ascaris dispar_. From the ring-necked pheasant (_Ph.
torquatus_) and from the black-backed Kaleege (_Euplocomus melanotus_),
and also from a cheer pheasant (_Ph. Wallichii_), I obtained abundance
of _Ascaris vesicularis_. From the ashy-headed goose (_Chloephaga
poliocephala_) examples of _Str. tubifex_ and _Str. nodularis_. This
bird also yielded a new species (_Str. acuticaudatus_). From a tinamou
(_Tinamus_) I obtained the _Ascaris strongylina_ of Rudolphi (_Str.
spiculatus_, mihi). From amongst our British birds I have obtained
_Asc. depressa_, _Trichosoma falconum_ and _Hemistoma spathulum_,
from the kite (_Falco milvus_). Of these three worms, the last named
was also found in the long-eared owl (_Strix otus_), whilst the first
likewise occurred in a kestrel (_Falco tinnunculus_) and in a honey
buzzard (_Pernis apivorus_). I may add _Filaria attenuata_ from a
peregrine (_F. peregrinus_); and _F. leptoptera_ from a sparrow
hawk (_Accipiter nisus_). From the redshank (_Totanus calidris_) I
obtained _Tænia variabilis_, and from the curlew (_Numenius arcuata_)
_T. sphærophora_; and from various gulls (_Larus glaucus_ and _L.
tridactylus_) the _Tetrabothrium cylindraceum_. Also from the grey
gull _Echinostoma spinulosum_. From the red-throated diver I procured
_Tetr. macrocephalum_. I found this tapeworm also in the guillemot
(_Uria troile_), together with a nematode (_Ascaris spiculigera_)
two examples of which were lodged in the right auricle of the heart.
From a capercaillie (_Tetrao urogallus_) I have obtained a species of
_Ligula_, and likewise numerous examples of _Trichosoma longicolle_. Of
necessity, this brief notice only comprises a small part of the avian
entozoa contained in my collection, many of which I have not had time to
describe, whilst, as regards others, I can only say that they remain in
abeyance for examination and identification.
Mr Brotherston has recently recorded an interesting find (made Nov.
25th, 1874) of nematodes in the legs of the lesser grebe (_Podiceps
minor_), and also (Feb. 27th, 1878) in the waterhen (_Gallinula
chloropus_). Both limbs of both birds were infested. The worms of the
grebe were spirally coiled amongst the muscles and tendons near the
lower end of the tibia, and when unrolled measured about an inch in
length. The parasites of the waterhen were similar in appearance. Not
improbably these were all sexually-imperfect female examples of _Filaria
acuta_ hitherto found in the abdomen of grebes.
The British Museum contains many interesting specimens purchased from
the collection of Von Siebold, but they are practically inaccessible
to investigators. The entozoa in the Hunterian Collection, though few
in number, are in an excellent state of preservation, and at all times
accessible to visitors.
The ectozoa of birds are too numerous to be dealt with in these pages.
References to recent papers by Haller, Mégnin, and Westwood will be
found below. The insects infesting the domestic fowl have been alluded
to in connection with the occurrence of poultry-lousiness in the horse.
BIBLIOGRAPHY (No. 57).--(Anonymous), “On the (gape) Diseases of Fowls,”
the ‘Veterinarian,’ p. 267, 1841.--(Anon., initialed “Q.”), Letter on
the “Grouse Disease,” in the ‘Times,’ Sept. 5, 1874.--(Anon.), “On
Grouse and Partridge Disease,” being annotations in the ‘Lancet,’
Sept. 4, 1875, pp. 360 and 361.--(Anon.), “Grouse Disease,” letter
signed “R.” (probably from Lord Ravensworth), in ‘Land and Water,’ Aug.
16, 1873.--(Anon.), “Grouse Disease,” article (from “W. C.”) in the
‘Field,’ Aug. 2, 1873 (criticising my brochure.--T. S. C.).--_Arlong_,
“Note on Tænia from the Fowl,” ‘Rec. Méd. Vét.,’ 1875.--_Baird, W._,
“Descr. of _Tænia calva_ from the Grouse,” in ‘Brit. Mus. Catalogue,’
p. 83.--_Blavette_, “Descr. of a Verminous Disease among Fowls,”
‘Veterinarian,’ p. 649, 1840.--_Brotherston, A._, “Parasitic Worms in
Legs of Grebe (_Podiceps minor_) and Water-hen (_Gallinula chloropus_),”
‘Science Gossip’ for April, 1878, p. 88, and in ‘Proceedings of the
Berwickshire Naturalists’ Club,’ vol. viii, p. 288.--Carter, B. (see
Cobbold).--_Chapman, H. C._, “Description of a new Tapeworm from Rhea,”
‘Proceed. Phil. Acad.,’ 1876, p. 14.--_Chatin, J._, “Étude sur des
helminthes nouveaux ou peu connus (treating of a Cyathostoma, from
_Anas tadorna_ and _Sclerostoma pelecani_),” ‘Annales des Sciences
Naturelles,’ 1875.--_Cobbold_, ‘The Grouse Disease, a statement
of facts tending to prove the Parasitic Origin of the Epidemic,’
London, 1874.--_Idem_, Letter in the ‘Field,’ Sept. 9, 1872.--_Idem_,
“Contributions to our Knowledge of the Grouse Disease, with description
of a new Species of Entozoon,” ‘Veterinarian,’ March, 1873; see also an
article (by Brudenell Carter) in the ‘Times’ for Sept. 5, 1874; repr. in
the ‘Veter.,’ Oct., 1874.--_Idem_, “Remarks on the Entozoa of the Common
Fowl and of Game-birds, especially in relation to the Grouse Disease,”
the ‘Field,’ Sept. 14, 1867, and ‘Brit. Assoc. Rep.,’ 1867.--_Idem_,
“On Sclerostoma and the Disease it occasions in Birds,” ‘Linn. Soc.
Proc.,’ 1861; repr. in the ‘Field,’ June 22, 1861, and in ‘Edin. Vet.
Rev.,’ vol. iii, p. 439, 1861, also in Tegetmeier’s work on ‘Poultry;’
see also a comment on “Gapes,” by “Umbra,” in the ‘Field,’ June 29,
1861.--_Idem_, “Parasites from the Zoological Gardens,” ‘Intellectual
Observer,’ 1862.--_Idem_., “Notes on Entozoa (species Nos. 1, 7, 9,
12),” in ‘Zool. Soc. Proc.,’ 1873-76.--_Idem_, ‘Linn. Soc. Trans.,’
1858.--_Idem_, “On Entozoa of Birds and Fishes, collected by Mr Charles
W. Devis,” ‘Zool. Soc. Proc.,’ 1865.--_Idem_, “Note on Entozoa in
the Crested Grebe,” the ‘Field,’ March 29, 1873.--_Colquhoun, W._,
‘Remarks on the decrease of Grouse, and on the Grouse Disease (Gapes),’
Edinburgh, 1858; see also a notice in ‘Edin. Vet. Rev.,’ vol. i, April,
1859.--_Crisp, E._, “Note on Hydatids in an old Honduras Turkey,”
‘Path. Soc. Trans.,’ 1863.--_Idem_, “On Sclerostoma,” ‘Rep. of Path.
Soc.,’ in ‘Med. Times and Gaz.,’ Oct. 26, 1876, p. 474.--_Idem_, “Note
on Filaria in the Heart of a Peregrine Falcon,” ‘Path. Soc. Trans.,’
1854.--_Davaine_, ‘Syngame de la trachée,’ p. 37, and ‘Synops.’ cxiv,
in his ‘Traité.’--_Devis, C. W._ (see Cobbold).--_Diesing_, ‘Revis.
der Myzelminthen,’ Abtheil. “Trémat.,” 1858.--_Idem_, “Tapeworm
from Podiceps,” in his ‘Zwanzig Arten von Cephalocotyleen,’ Wien,
1856.--_Idem_, see various species in his ‘Revisionen,’ given in Bibl.
No. 58.--_Eames, C. J. L._, “On Tapeworm in Blackbirds,” letter to
the ‘Lancet,’ June 9, 1877, p. 863.--_Farquharson, R._, “The Grouse
Disease (due to a contagious fever),” letter to the ‘Lancet,’ Sept.,
1874.--_Fergusson, J._, “On Grouse Disease,” letter in the ‘Times,’
July 16, 1878.--_Gentles, T. W._, “Tapeworm in Birds,” letter to the
‘Lancet,’ Jan. 18, 1868, p. 106.--_Haller, G._, “Freyana und Picobia,
zwei neue Milbengattungen,” in ‘Sieb. u. Köll. Zeitsch.,’ 1877, s.
181.--_Johnston, D._, “On the Grouse Disease,” letter in the ‘Lancet,’
Sept. 20, 1873, p. 441.--_Krabbe_, ‘Bidrag til Kundskab om Fuglenes
Bændelorme,’ Copenhagen, 1869 (contains a summary in French, ‘Recherches
sur les Ténias des Oiseaux’).--_Linstow, O. von_, “Euthelminthologica”
(containing descriptions and notes on worms from birds, fishes,
reptiles, and mollusks), ‘Archiv für Naturgeschichte,’ 1877.--_Idem_,
“New Flukes (_Dist. vitellatum_ and _D. macrophallus_) from _Totanus
hypoleucus_, and _D. cælebs_ from Fringilla,” Beobacht. in ‘Arch. f.
Naturg.,’ 1875, s. 189-193.--_Maclagan_, “Note on the Grouse Disease,”
‘Proc. Roy. Soc. of Edin.,’ April 20, 1874, p. 378.--_Marion_, “Révis.
des Némat. du Golfe de Marseilles,” ‘Compt. Rendus,’ 1875.--_Mégnin,
P._, “On Harpirhynchus and other Mites,” in ‘Rev. f. Thierheilk.,’
Oct., 1878, s. 146.--_Idem_, “Mémoire sur les Cheylétides Parasites
(Picobia, &c.),” ‘Journ. d’Anat. et de Physiol.,’ 1878; see also
‘Rev. f. Thierheilk.,’ Sept., 1878 _et seq._--_Molin_, in his various
monographs (quoted in Bibl. Nos. 54, 56, and elsewhere).--_Montagu,
G._, “Account of a species of Fasciola which infests the Trachea of
Poultry, with a mode of Cure,” ‘Memoirs of the Wernerian Nat. Hist.
Soc.,’ vol. i, p. 194, 1811.--_Perrier_, ‘On Syngamus’ (brochure, Paris,
1875).--_Pulteney, R._, “On Ascarides discovered in _Pelicanus carbo_
and _P. cristatus_,” ‘Linn. Trans.,’ vol. v, 1800, p. 24.--_Röll_,
“Beitrag. zur Entwickelungsgeschichte der Tænien,” ‘Verh. d. Würzb.
p. m. Ges.,’ Bd. iii, 1852, s. 51.--_Sanderson, J. B._, “On Grouse
Disease,” ‘Brit. Med. Journ.,’ May 15, 1875.--_Small, M._, “Worms
in the Eyes of Geese,” from the ‘Irish Farmer’s Gaz.,’ in the
‘Veterinarian,’ 1862, p. 19.--_Tait, L._, “Tapeworm in Birds,” letters
to the ‘Lancet’ for Jan. 25, 1868, p. 145, and Feb. 8, 1868, p. 214;
see also “Pediculus,” _ibid._, p. 180.--_Tegetmeier_, “On the Grouse
Disease,” in the ‘Field,’ Sept. 12, 1874.--_Thick_, “Letter on the
Cure of Gapes,” in ‘Land and Water,’ Aug., 1867, p. 77.--_Vaughan_,
“The Grouse Disease,” in the ‘Field,’ Aug. 23, 1873.--_Villow, A._,
“Sur les migrations, et les Métamorphoses des Trematodes,” ‘Comptes
Rendus,’ 1875, and ‘Ann. Nat. Hist.,’ 1875 (chiefly on flukes of the
sea-lark, _Tringa alpina_).--_Idem_, “Sur le syst. nerveau,” &c.,
_ibid._, 1875.--_Idem_, “On the Helm. Fauna of the Coast of Brittany
(chiefly from birds),” ‘Ann. Nat. Hist.,’ from ‘Comp. Rend.,’ 1875,
p. 1098, and from ‘Arch. de Zool. Expérim. et gén.,’ 1875.--_Idem_,
“Sur l’appareil des Trematodes (_Dist. insigne_),” ‘Compt. Rend.,’
1875.--_Wedl, K._, ‘Anatomische Beobachtungen ueber Trematoden,’ Wien,
1858 (contains excellent descriptions of numerous flukes, chiefly
from birds).--_Westwood, J. O._, “New Flea on a Fowl (Sarcopsillus),”
‘Entom. Month. Mag.,’ xi, p. 246, 1875.--_Wiesenthal, A._, “Account of a
Parasite infesting the Trachea of Fowls and Turkeys in America,” ‘Med.
and Phys. Journ.,’ vol. ii, p. 204, 1799.--_Wyman_, “On Eustrongyli
within the Cranium of Water-Turkeys,” ‘Proc. Boston Nat. Hist. Soc.,’
1868.--_Youatt_, “On a Verminous Disease in Poultry” (being a letter to
him), ‘Veterinarian,’ p. 648, 1840.--_Zeller_, “On Leucochloridium,”
from ‘Zeitsch. f. wissensch. Zool.,’ 1874, s. 564, and from ‘Bibl. Univ.
Bullet. Sci.,’ 1874, p. 366, in ‘Ann. Nat. Hist.,’ Feb., 1875.
PART II (REPTILIA).
Much that I have advanced in respect of the parasitism of birds holds
good in the case of reptiles. I cannot recapitulate. The saurians,
ophidians, and chelonians are extensively infested, but in this respect
the amphibian frogs, toads, and salamanders are probably the most
victimised. If, on the one hand, comparatively few tapeworms have
been found in reptiles, it may, on the other hand, be said that the
Echinorhynchi come into prominence, causing serious injury to reptilian
hosts. Serpents and chameleons are particularly liable to have their
lungs infested by acanthocephalous entozoa, these organs being also
attacked by pentastomes. I have received evidence of fatal epizoöty
amongst chameleons from this source; and I have been requested to
suggest a remedy. To prevent outbreaks of entozoal disease is one thing;
to offer a radical cure when the parasites are firmly anchored within
the pulmonary organs is quite another matter.
As remarked in my ‘Entozoa,’ the trematodes display a great partiality
for batrachians, more than half a dozen different species of fluke being
known to infest the common frog. Flukes are likewise tolerably abundant
in the saurian and chelonian reptiles. I regret that I cannot find space
so much as to enumerate the species. As one would naturally expect,
the frog has been exhaustively anatomised and examined for entozoa,
and it was this creature that supplied Leuckart and Mecznikow with
the materials which led to their well-known discovery and controversy
respecting the development, dimorphism, and parthenogenetic phenomena
exhibited by _Ascaris nigrovenosa_. I cannot give the facts in detail.
Female examples of the worm live in the lungs of the frog. Their young,
as embryos, pass into the damp earth and mud, where they grow up into
sexually-mature forms different from the parent worms found in the frog.
These free adult worms, male and female, produce rhabditiform embryos
which present characters of their own and attain a certain stage of
growth. At this stage they are conveyed into the lungs of the frog
where they arrive at sexual maturity. As there are no male worms in the
frog, it is probable that the embryos of these parasitic females are
agamogenetically produced by internal budding, the sexual influence
of the free males being, as it were, continued onward without actual
contact with the parasitic females. Amongst the interesting parasites of
the frog one must also mention _Amphistoma subclavatum_ and _Polystoma
intergerrimum_. The former worm resides in the large intestine and the
latter in the urinary bladder. The larvæ (_Cercaria diplocotylea_) of
this amphistome reside in or upon the body of water-snails, and, like
the cercarian larvæ of polystoma, they are furnished with eyes. I state
this fact on the authority of Pagenstecher; and, since I cannot devote
a special section to the entozoa of mollusks, I repeat, in part, the
valuable results which Pagenstecher published many years back and which
have a permanent value in relation to the origin of parasitic diseases
resulting from flukes. In the memoir quoted below, Pagenstecher gives
the following conclusions (_Schlussbemerkungen_):
“(_a_).--The eggs of the trematoda vary in respect of size, form,
and color, being either furnished or not with a lid, and accordingly
distinguishable. In the mature condition they contain a ciliated or a
non-ciliated embryo of unequal growth, this embryo partly increasing
in size even after its birth. In various conceivable ways the eggs
themselves, or the embryos which have quitted their shells, arrive in
and upon the bodies of mollusks, where they are consequently found.
In this situation the egg opens, or the ciliated covering decays, and
the contained motionless germ--which in itself offers no distinctive
characters--having become free, grows into a nurse, or forms several
nurses within itself.
“(_b_).--Whilst some of the trematodes display a highly organised nurse
condition, others exhibit only a simple kind of germ-sac. Both forms,
nevertheless, appear to occur in one and the same species, probably
depending upon external causes.
“(_c_).--The organised nurses (or _rediæ_, as they are termed) have a
mouth and a strongly marked muscular œsophagus, which is continued into
a short or prolonged, single, blind intestine, or the latter may be
double. The expulsion of animals developed within them I have only seen
to take place through an opening at the hinder extremity. Old rediæ lose
their structure. I did not observe any vascular system. Tailed trematode
larvæ (_Cercariæ_), as well as rediæ themselves, are developed within
the rediæ, this variation of nurse-contents probably depending on the
season.
“(_d_).--No independent new germ-sacs are developed within the simple
unorganised germ-sacs (sporocysts), and only such trematode larvæ as
are capable of arriving at sexual maturity are furnished with special
appendages.
“(_e_).--When the immature contents of both nurse forms (_i.e._ of
sporocysts and rediæ) are accidentally set free, and are situated within
the organs of nutrition of the living host, then they appear prepared
to develop themselves anew into nurse forms; and, moreover, cercariæ
whose development has not yet attained a definite stage--and even their
tails also--appear to enjoy a similar capacity. Some nurses are likewise
capable of multiplication by division and budding.
“(_f_).--Some germ-sacs have the property of developing within
themselves cercaria-like larvæ--which are different from the true
cercariæ--from whose body the development of a _distoma_ may take place,
while their single or double tail-like appendages in all cases develop
anew into germ-sacs. To this class belong _Bucephalus_ and _Distoma
duplicatum_.
“(_g_).--All the cercaria at present known are destitute of eyes,
but other forms of trematode larvæ are furnished with visual organs.
Accordingly, I never found eyes in young distomata whilst they were
in their last dwelling-place, but eyes are certainly present in the
young forms of _Polystoma_ and _Amphistoma_. The supposition that a
spontaneous wandering is associated with eyes is not yet confirmed in my
experience.
“(_h_).--As a means of distinguishing the different forms of Cercariæ,
amongst other indications, their places of dwelling may be useful,
because each mollusk only harbors a limited number of species.
Notwithstanding, Professor Filippi is in error if he believes that every
species of mollusk carries only a single armed form of cercaria. A
migration of the cercaria is indispensable to its perfection.
“(_i_).--Many larval trematodes form cysts round themselves, probably
by means of a special organ of secretion, and also by the epidermis.
Their future destiny necessitates this. The sporocysts apparently fulfil
towards the larvæ, which are developed within them, a similar purpose,
namely, a protection against the stomachal digestion of the new host. In
the pupa condition the development of the larva, which has now thrown
off the tail, makes greater or less progress, according as to whether
it is surrounded by nourishment or not. In particular, while in this
stage, the different kinds of hooks for migratory purposes make their
appearance, always, without doubt, after the shedding of the skin. Other
trematodes pass through this tail-less sexually-immature stage without
any cyst. I have not yet seen any larval trematode forms which had been
produced in sporocysts or rediæ without appendages; they appear to
occur, nevertheless.
“(_k_).--As the larvæ exist only in a few hosts--and most of them dwell
only in one species of animal--so, also, the continued progress towards
sexual maturity only succeeds in the case of certain well-defined larval
organisms, but the digestion of the cysts and liberation of the larvæ
may be accomplished in various animals.
“(_l_).--The armed Cercariæ appear to be larvæ of the spine-covered
distomes of amphibia; for, as examples, the _Cercaria ornata_ becomes
transformed into _Distoma clavigerum_, and _C. armata_ into _Distoma
endolobum_; the _Dist. duplicatum_ and _Cerc. diplocotylea_ are,
apparently, the juvenile forms of _Dist. cygnoides_ and _Amphistoma
subclavatum_. The _Dist. echiniferum_ of Paludina could neither be
advanced in development in the frog or duck, nor could all the other
larvæ which I subjected to experiment be developed either in the green
or brown frogs.
“(_m_).--When young trematodes arrive at the right place for their
maturation, then the male generative structures develop before the
female organs, and in the subsequent excess of egg production the form
and structure of the animal becomes obliterated.
“(_n_).--The yelk-molecules surrounding the germinal vesicle are not
directly transformed into an embryo.”
As regards the acanthocephalous parasites of reptiles, I may observe
that _Echinorhynchus anthuris_ is very common in the lesser water newt
(_Lissotriton punctatus_). In the accompanying illustration (Fig. 76) I
have represented the free ovarian egg-bearing bodies, the development of
the ovum, and the adult worms. For anatomical details, however, I must
refer to my earlier treatise (‘Entozoa,’ p. 100 _et seq._).
[Illustration: FIG. 76.--_Echinorhynchus anthuris._ 1, Attached to the
intestine; 2, specimen enlarged; 3, ovarian vesicle, including germs; 4,
germs in various stages; 5, vesicle with germs more advanced; 6, 7, eggs
in their capsules; 8, free egg. Original.]
Amongst the species of entozoa that were found by me at the Zoological
Society’s Menagerie I may mention _Distoma coronarium_ and _Ascaris
lineata_, from the intestines of _Alligator mississippiensis_; _Dist.
Boscii_, from an American snake (_Coluber_); an immature nematode, from
the heart of _Coluber Blumenbachii_; and _Echinorhynchus inflexus_,
attached to the intestines of a snapping turtle (_Chelydra serpentina_).
I may add that the lungs of the alligator also contained examples of
Diesing’s _Pentastoma oxycephalum_. An Egyptian hooded snake (_Naia
haje_), which died at the Zoological Gardens in 1859, furnished a new
species of pentastome (_P. multicinctum_). Dr George Harley described
and anatomised this worm with remarkable care. To Harley’s memoir Prof.
Leuckart did ample justice in his work on the ‘Pentastoma.’ Several
new species of reptilian entozoa have recently been described by Dr
von Linstow; and Dr Solger has found a new trichosome (_T. recurvum_)
beneath the skin of a young crocodile (probably _Croc. acutus_). For
further particulars I refer to the revised descriptions and additions by
Diesing, Molin, Schneider, and other systematists.
BIBLIOGRAPHY (No. 58).--_Baird, W._, “Description of a new Entozoon from
the Diamond Snake,” in ‘Proceed. Zool. Soc.’ for 1865, p. 58, and in
‘Ann. Nat. Hist.’ for July, 1865, p. 52.--_Blanchard_, “On Polystoma,”
‘Ann. des Sci. Nat.,’ 3e ser., viii, p. 331.--_Canton, E._, “An
account of some Parasites attached to the Conjunctivæ of the Turtle’s
Eyes,” ‘Quart. Journ. Micr. Sci.,’ and ‘Dublin Med. Press,’ 1861 (with
remarks by myself).--_Cobbold_, ‘Notes,’ &c. (l. c., Bibl. No. 57),
and in ‘Linn. Trans.,’ 1857.--_Crisp, E._, “Note on Cysticerci and
Trichocephali from an Alligator,” ‘Path. Soc. Trans.,’ 1854.--_Diesing_,
‘Revision der Cercarieen,’ 1858; ‘Revis. der Myzelminthen,’ 1858;
‘Nachträge (u. s. w.),’ 1859; ‘Revis. der Nematoden,’ 1860; ‘Revis.
d. Turbellarien,’ 1861; ‘Revis. d. Cephalocotyleen,’ 1863.--_Idem_,
‘Monographie d. Gatt. Amphistoma und Diplodiscus,’ and ‘Nachträge
zur Monog. der Amph.,’ 1839.--_Dujardin_, ‘Hist. d. Helm.’ (l. c.,
pp. 320, 526, &c.).--_Eberth_, “On _Myoryktes Weismanni_ from the
Muscles of the Frog,” trans. by Busk, from ‘Siebold und Kölliker’s
Zeitschrift,’ in ‘Lond. Micr. Journ.,’ Jan., 1864.--_Gastaldi_, ‘Cenni
sopra alcuni nuovi Elmint.,’ Torino, 1854 (new flukes from frogs and
salamanders).--_Glüge_, “On Entozoa in the Vessels of Frogs,” from
‘Comptes Rendus,’ in ‘Micr. Journ. and Struct. Rec.,’ p. 207, 1842;
see Grübe and Valentin.--_Grübe_, “On the Entozoa of the Frog, and on
the Pathology of that Batrachian,” from ‘Comptes Rendus,’ in ‘Micr.
Journ. and Struct. Rec.,’ p. 246, for 1842; see also Mandl.--_Harley,
G._, “On the Anatomy of a new Species of Pentastoma found in the Lung
and Air-sac of an Egyptian Cobra,” ‘Proc. Zool. Soc.,’ June, part
xxv, p. 115, 1857.--_Leuckart_, ‘Bau und Entwickelungsgeschichte
der Pentastomen,’ Leipsig, 1860.--_Linstow_, ‘Enthelminth.’ (l.
c., Bibl. No. 57).--_Macalister, A._, “On the presence of certain
Secreting Organs in Nematoidea,” ‘Ann. and Mag. of Nat. Hist.’ for
1865.--_Idem_, “On the Anatomy of _Ascaris dactyluris_,” ‘Proc. Nat.
Hist. Soc. of Dublin,’ vol. iv, 1865.--_Mandl_, “Development of
Entozoa (_Ascaris nigrovenosa_ of the frog),” from ‘Rep. of French
Acad. of Sci.,’ in ‘Month. Journ. of Med. Sci.,’ vol. ii, p. 1081,
1842.--_Molin_, ‘Monog. del gen. Myzelminth; Mon. del gen. Physaloptera;
Mon. del gen. Histiocephalus; Mon. del gen. Spiroptera;’ Wien,
1859-60.--_Pagenstecher_, ‘Trematodenlarven und Trematoden,’ Heidelberg,
1857.--_Sibbald, J._, “On the _Nematoideum natricis_,” ‘Path. Soc.
Trans.,’ vol. viii, 1857.--_Solger_, “Ueber eine neue species von
Trichosoma,” ‘Arch. f. Naturg.,’ 1877.--_Valentin_, “On Parasites in the
Bladder of the Frog” (from ‘Repertorium’), in ‘Micr. Journ. and Struct.
Record,’ 1842, p. 183.--_Vogt, C._, “On Filaria in the Vessels of the
Frog,” from ‘Müller’s Archiv,’ in ‘Micr. Journ. and Struct. Rec.,’
p. 241, 1842.--_Wedl, F._, “Beiträge zur Lehre von den Hæmatozoen,”
‘Sitzungsb. Akad.,’ Wien, 1850 (from the blood of frogs, &c.).--_Zeller,
E._, “Weiterer Beitrag zur Kentniss der Polystomen,” ‘Sieb. und Köll.
Zeitschrift,’ 1875.
PART III (PISCES).
Swarms of entozoa infest fishes, and it is hard to say whether they
are less numerous in the inhabitants of fresh water than in those of
salt water. More attention has been paid to the helminths of the fishes
than to the internal parasites of birds and reptiles, consequently,
the number of known species must be estimated by many hundreds. In
like manner a great deal has been written respecting the ectozoa of
fishes. These parasites, often called fish-lice, belong chiefly to the
haustellated crustaceans, and are better known by the title of _Epizoa_.
No account of them can be afforded in this treatise, but some trifling
notice of the literature of the subject will be given below.
About a hundred distinct species of fluke have been described as
infesting fishes. Not many of these worms possess more than a zoological
interest; nevertheless, from that point of view certain types are very
curious. Most of the species dwell in the stomach and intestines, but,
as more or less remarkable exceptions, I may mention _Distoma seriale_
infesting the kidney of _Salmo umbla_, _D. longum_ (Leidy) from the
pharynx of _Esox estor_, _D. polymorphum_ from the urinary bladder of
the common pike (_Esox lucius_), _D. obesum_ from the gall bladder of
_Salminius_ and other Brazilian fishes (_Xiphostoma_, _Leporinus_), _D.
tornatum_ attached to the gills of _Coryphæna hippuris_, _D. rosaceum_
attached to the palate of _Lota communis_, and _D. contortum_ attached
to the gills of _Orthagoriscus mola_. Most of the forms found encysted
are sexually-immature worms. To these belong _D. annuligerum_, found
by Nordmann in cysts in the vitreous humour of the eye of the perch
(_Perca fluviatilis_), and _D. embryo_ from the liver and peritoneum
of _Acerina vulgaris_. One of the largest and most remarkable of the
flukes inhabiting marine fishes is the _Distoma clavatum_, found by
Tilesius in the stomach of _Pelamys_, by Pohl in _Thynnus_, and by
Bosc in _Coryphæna_. In the last-named fish it has been found adhering
to the gills, in the liver, and in the intestines. In August, 1865, I
obtained this parasite from a sword-fish (_Xiphias gladius_), and in
the same piscine host I also found examples of four other species of
helminths (_Tetrarhynchus attenuatus_, scolex of another tetrarhynch,
_Bothriocephalus plicatus_, _Ascaris incurva_). Believing _Distoma
clavatum_ to represent several forms hitherto regarded as distinct,
I append a few particulars respecting it. Five examples of this worm
were obtained by me from the stomach of a sword-fish. Generally they
varied in length from four lines to two inches. They differed somewhat
in shape, but all had the so-called head and neck directed backwards.
Below the ventral sucker the two largest specimens were distended with
eggs and black pigment. All of them likewise exhibited more or less
well-marked transverse rugæ, the last ring surrounding an orifice which
represented the outlet of a large contractile vesicle. The eggs averaged
1/800″ in length.
When revising the entozoa of the Museum of the Royal College of Surgeons
I encountered many parasites without labels attached. Amongst these were
several flukes, which, though differing from each other in size and
shape, appeared to be identical. One of these specimens turned out to
be the particular _Distoma clavatum_ described and figured by Professor
Owen in the ‘Zoological Society’s Transactions.’ Several of the others
I made out to be part of a series contributed by Mr George Bennett, who
also gave specimens to the British Museum, but the College Museum stores
contained yet a third group of specimens of uncertain history. The large
fluke described by Prof. Owen was formerly in the collection of the
Rev. Lansdown Guilding. In Dr Baird’s catalogue the specimens presented
by Mr Bennett are stated to have come from the stomach of a bonito, and
probably Mr Guilding’s specimens may be referred to the same “host.” Be
that as it may, the specimens differ from each other in a very striking
manner. In the year 1730 M. Garsin first described this worm under the
generic title of _Hirudinella_. He says:--“Cet insecte tiré de l’estomac
de la Bonita ne vécut qu’environ deux heures. Exposé à l’air il étoit
languissant, et reprenoit de la vivacité dans de l’eau de mer. Il
diminua sensiblement de volume pendant qu’il vivoit encore.” M. Garsin’s
description is accompanied by three figures. His specimens do not appear
to have exceeded 1-1/2″ in length. In 1774 Pallas described a trematode
(_Fasciola ventricosa_). It measured two inches in length. All that
he says regarding its source is as follows:--“Ex Amboyna missum fuit
singulare hoc molluscum, quod ad aliud quam Fasciolarum genus referre
non potui, in quo quasi gigas erit.” He remarks upon its pale white
color, and notices particularly the soft elastic body proper, which when
wounded gave out a dark matter resembling soot. This material, when
examined with the microscope, appeared fresh; it was not the result of
decomposition. Pallas also gives many other details, accompanied by a
figure. In 1790 Menzies likewise described and figured a fluke about two
inches long. He calls it _Fasciola clavata_:--“It is of whitish color,
somewhat pellucid, discharging at its mouth a black-colored fluid, which
can easily be perceived through its body. I have often found it,” he
adds, “in the maws of the bonito, between the tropics in the Pacific
Ocean.” Notwithstanding the similarity of description, Menzies does not
appear to have recognised the identity of his worm with that described
by Pallas. Prof. Owen, however, subsequently established this identity,
and referred to this species as the _Fasciola clavata_ seu _ventricosa_.
On the other hand, the British Museum Catalogue represents Pallas’s worm
as specifically distinct from that of Menzies, but as identical with the
specimen described by Prof. Owen from Mr Guilding’s collection.
In 1802 Bosc described and figured a trematode under the title
of _Fasciola fusca_. This he obtained from the intestines of a
dorado. In form it differs considerably from the foregoing species.
Bosc’s description runs as follows:--“Brune, la partie postérieure
très-renflée, presque ovale, la partie antérieure mince, cylindrique,
inégale, avec deux petits tentacules en dessous. Le suçoir de l’anus
très grand.” Bosc recognised the identity of this worm with the _Distoma
coryphænæ_ of Rudolphi, and systematists generally have adopted his
synonymy. In the British Museum Catalogue the _Fasciola fusca_ and _F.
ventricosa_ of Pallas are regarded as one and the same species. The
existence of two small tentacles is certainly peculiar.
In 1827 Nardo obtained two very large flukes from the stomach of a
fish captured in the Gulf of Venice during the month of September. He
calls the fish _Prostostegus prototypus_, which appears to be the same
as the _Luvarus imperialis_ of Rafinesque. One of the parasites, being
five inches in length, he named _Distoma gigas_. His description is
as follows:--“Distoma teres, rubrum, retractile; poro ventrali minimo
cujus apertura magna, rotunda, ciliata; poro antico terminali, parvo;
collo brevi, retrorsum divergente, extensili, apice angusto, basi lato;
cauda longa, postice incrassata et in apice obtusa oscula donata.” The
alleged ciliated character of the ventral sucker, was perhaps due to a
wrinkled state of the lip. Apart from this character, I see no reason
for supposing this parasite to be distinct from the _Distoma clavatum_
procured by Mr Guilding, or the _Fasciola ventricosa_ described by
Pallas. The intestines of the fish harbored another parasite (_D.
Raynerianum_). Unfortunately, Nardo gives no figure of _Distoma gigas_.
It is the longest fluke known to science.
In the year 1835 Professor Owen communicated the memoirs already alluded
to. In his paper he discussed questions relating to the structure of
_Distoma clavatum_, and threw much light upon its anatomy, but I believe
that the large “lateral cavities” described by Owen are neither more or
less than the somewhat unusually distended alimentary cæca.
In 1845 Dujardin placed the worm with the true distomes, yet, at the
same time, expressed grave doubts as to whether it were, in any sense,
a fluke. “Ce ver,” he remarks, “n’est certainement pas un distome ni
même un trématode. Si sa forme extérieure et ses deux oscules lui
donnent quelque ressemblance avec les distomes, sa structure musculeuse
la rapproche davantage des Gordius, et son tégument ressemble à celui
des siponcles.” M. Dujardin examined the specimens preserved in the
Paris Museum, and with regard to one particular example, described as
“Fasciola, trouvé dans la mer de Nice,” he says, it presents “une
certaine analogie avec le prétendu _Distoma clavatum_.” Dujardin himself
was somewhat puzzled by the resemblance in question. He does not
appear to have examined fresh specimens, yet he mentions the species
as tolerably common in the bonito, and occasionally present in the
tunny. At all events, it appears that the rightly so-called _Distoma
clavatum_ is not unfrequently taken from the ocean in the free state.
In concluding my notice of this remarkable worm I can only add that
after examining numerous specimens both in the fresh and preserved
states, I have formed the opinion that the following specific names all
refer to one and the same parasite:--_Distoma clavatum_, Rudolphi; _D.
coryphænæ_, Rud.; _D. gigas_, Nardo; _Fasciola clavata_, Menzies; _F.
coryphænæ_, Bosc; _F. coryph. hippuridis_ and _F. Scombri pelamidis_,
Tilesius; _F. fusca_, Bosc; _Hirudinella marina_, Garsin; _H. clavata_,
Baird. In this list of synonyms we may probably also include Rudolphi’s
_Distoma tornatum_.
[Illustration: FIG. 77.--_Echinostoma hispidum._ Magnified. Original.]
In addition to these distomes there are numerous piscine flukes which
may fairly be relegated to other genera. Thus, provisionally, I elevated
Dujardin’s sub-genus _Echinostoma_ into a separate genus; and on
what I considered sufficient grounds I established several other new
genera from amongst the more curious flukes that had been described as
infesting fishes (_Wedlia_, _Köllikeria_). In the genus _Echinostoma_
the oral sucker is either surrounded by a circle of little spines, or it
occupies the centre of a disk, which is cleft at the ventral or anterior
aspect. In the latter case the disk is either bordered both laterally
and above by spines, or there are two large lobed appendages, whose
margins are furnished with spines. In other respects this genus nearly
corresponds with the distomes, the simple digestive tubes bifurcating
immediately below the œsophageal bulb. The specimen of _Ech. hispidum_
here drawn (Fig. 77) was taken by me from the spiral intestine of a
sturgeon (1855), in which fish it occurs very abundantly. The figure
represents a back view of the head and a lateral view of the body, the
neck having been slightly twisted. The ventral sucker is concealed, but
the transparency of the skin permits a view of the internal organs.
Another remarkable genus, established by Von Siebold, is _Gasterostoma_.
In this genus the ventral sucker has taken the position usually assigned
to the oral opening; the latter being near the centre of the body. The
digestive cæca also disappear, leaving only a short stomachal cavity,
which reminds one of the same viscus in imperfectly organised sporocysts
or rediæ. When _G. gracilescens_ first came under my observation I
followed Rudolphi in describing it as a distome (_D. gracilescens_). The
anatomy of the genus has been illustrated by Von Siebold; from whose
observations also it may be inferred that the larvæ are various forms
of _Bucephali_. Prof. Molin describes the water-vascular or respiratory
apparatus as consisting (in _G. fimbriatum_) of a broad central tube,
occupying the entire length of the body and opening externally at the
tail.
[Illustration: FIG. 78.--_Gasterostoma gracilescens._ Magnified.
Original.]
Amongst the more remarkable fluke-types may be mentioned Van Beneden’s
Nematobothrium (_N. filarina_), occupying the branchial cavity of
_Sciæna aquila_, also _Holostoma clavus_, found by Molin in the
intestines of _Gadus merlucius_, also _Köllikeria filicollis_,
occupying open follicles in the branchial cavity of _Brama Raii_.
The sexes in the last-named genus are distinct; male and female worms
together occupying each cyst. The genus _Monostoma_ is also largely
represented amongst fishes. Prof. Wedl found a species (_M. Wedlii_)
occupying follicles in the intestinal mucous membrane, and also adhering
to the fin rays of _Rhombus lævis_. I also found a species (_M. dubium_)
in a cyst attached to the ovary of _Gasterosteus spinachii_. Several
species of amphistomatoid worms were found by Natterer in Brazilian
fishes (_Cataphractus_, &c.), some of these representing distinct genera
(_Aspidocotylus_, _Notocotylus_), to which I found Sonsino’s remarkable
fluke (_Gastrodiscus Sonsinonis_, mihi) from the horse to be very
closely allied. In this connection must also be mentioned Grübe and
Wagener’s curious _Amphiptyches urna_, found attached to the branchiæ,
and also in the intestines of _Chimæra monstrosa_.
In addition to the above families and genera of digenetic flukes
infesting fishes we have the monogenetic tristomes and polystomes.
As remarked in my introductory treatise, the Tristomidæ display a
leech-like aspect, in consequence of which they have been placed either
along with the _Malacobdellidæ_, or in some other allied family of
the suctorial annelids. The tristomes are not strictly entozoa, yet
their internal organisation conforms more to the _Trematoda_ than to
the _Hirudinidæ_. Thus, they support two small suckers anteriorly and
one large sucker posteriorly, the body being externally smooth and
devoid of annulations. The tristomes have therefore no anus. In some
species the large caudal sucker is sessile, in others it is stalked
or pedunculated, being in either case bordered by a membranous fold
(Dujardin). All the species are hermaphroditic. They attach themselves
to the gills of fishes or to the general surface, selecting especially
the neighbourhood of the fins. Some species are parasitic on crustacean
parasites that are themselves attached to marine fishes. In the genus
_Udonella_ the mode of development is known to be simple and direct.
According to Van Beneden, the embryos are large and acquire the form and
characters of their parents whilst they are still within the egg-shell.
They are ready to assume an independent existence the moment they quit
the shell. The eggs are oval, the chorion being prolonged into a single
filamentary process or “holdfast.” Van Beneden compares a group of
them to a “bouquet of vorticells.” On quitting the shell the embryonic
_Udonella_ at once attaches itself to the _Caligus_, and there acquires
the adult condition. The _Polystomidæ_ comprise a variety of remarkable
genera. I accept this family as the equivalent of Dujardin’s first group
of trematodes which he termed “_Onchobothriens_,” rejecting only his
genus _Diporpa_, which is a juvenile condition of _Diplozoon_. In this
family Van Beneden includes the genera _Calceostoma_ and _Gyrodactylus_.
In all the polystomes we have a more or less ramified intestine, but
the reproductive organs conform to the general trematode type. All are
hermaphroditic, the eggs being supplied with filamentary appendages,
in some only at one pole of the shell, in others at both ends. The
water-vascular system is conspicuously developed. All the species are
supplied with prehensile hooks.
In the Diporpa condition of _Diplozoon_ there are two supernumerary
hooks, associated with a dorsal sucker at the centre of the body, and it
is by means of these organs that a conjugation between two such juvenile
forms is effected. These two individuals become organically united for
life, after the fashion of the Siamese twins. After conjugation the
sexual organs appear. In _Onchotyle appendiculata_ the lower end of
the body merges into a curious appendage, which is placed almost at a
right angle with the body itself, and in this way, as Van Beneden justly
remarks, the entire animal resembles a little hammer, the resemblance
being very much heightened by the circumstance that one end of the
appendage is cleft so as to correspond, as it were, with the notch which
we employ in the action of nail-drawing. The _Onchotyle appendiculata_
was first discovered by Kuhn attached to the gills of a dog-fish
(_Scillium catulus_), but it has since been found ectoparasitically
lodged upon other marine fishes. With the _Gyrodactylidæ_ I include Van
Beneden’s genus _Calceostoma_. The gyrodactyles have been classed with
the Polystomidæ. Amongst the characters standing out most prominently
are those having reference to peculiar hooks which project from the
great sucking disk. In _Calceostoma_ this mechanism is reduced to a
single horny structure placed at the margin of the caudal sucker in
the central line. In some Gyrodactyli the hooks are very numerous.
In _Gyrodactylus elegans_ the caudal sucker supports a pair of large
laterally-curved hooks, which are placed back to back in the centre
of the disk, being connected at their upper ends by a supplementary
semi-lunar bar. A series of tentacles serve to increase the prehensile
action of the sucker. In many species the males are supplied with
accessory horny developments. The genus _Gyrodactylus_ has been studied
by Nordmann, Von Siebold, G. Wagener, Van Beneden, and especially by
Wedl, who records the following results:--(_a._) “_Gyrodactylus_
is found on the gills of fresh-water fishes under numerous specific
forms, _G. elegans_ being also found by Creplin and Siebold on the
fins. Moreover, as I have found nearly every species of fish supporting
a particular gyrodactyle representative, it would seem that each
finny creature supplies its own _Gyrodactylus_. Sometimes two of them
are parasitic upon the same gill, being frequently associated with
_Trichodinæ_, as well as with the still unintelligible _Psorospermiæ_.
(_b._) The clasping apparatus at the posterior end of the body must--in
an animal so soft and constantly exposed to the passage of regular
currents--be comparatively strongly developed and accommodated to the
peculiar dwelling-places, and probably the varying character of the
latter supplies a reason why there should be so great a difference in
the mechanism of the hooks belonging to the disk. (_c._) The hooked
apparatus affords a very valuable and mathematically precise means of
diagnosis in the determination of species. This differentiation may be
accomplished by observing whether there are two or four large hooks;
whether there be one or two connecting portions, and by noticing their
several forms and relations to one another; and whether, again, there
are hooklets or not, remarking in the first instance their position,
form, distribution, and so forth. (_d._) The integument is sometimes
wrinkled transversely, at other times appearing to be smooth. (_e._)
The muscular apparatus is, in certain cases, very strongly developed.
In the majority of instances special muscles are inserted into the
handles of the hooks, and they are also very frequently directed into
the transverse muscles of the skin. In _Gyrodactylus crassiusculus_ we
find a _protrusor penis_ and _retractor palparum medius_. (_f._) Except
in the case of _G. elegans_, four so-called eye-spots are observed
at the anterior extremity of all Gyrodactyli. As Siebold says, they
answer the purpose of light-refracting organs. The palpi, which in
_G. crassiusculus_ are seen to contain muscular bundles, appear to be
retractile touch-organs, extending more or less prominently forward.
(_g._) Observations in regard to the alimentary canal are at present
incomplete, for only in the case of _G. cochlea_ did I find a single
gullet demonstrable. (_h._) _Gyrodactylus_ becomes sexually developed,
and cannot be regarded merely as a kind of ‘nurse.’”
[Illustration: FIG. 79.--_Gyrodactylus elegans_, containing an embryo.
_a_, _a_, Œsophagus; _g_, testis; _h_, _h_, sucker; _i_, _i_, large
hooks; _k_, spines. Magnified. After Van Beneden.]
So much for Wedl, whose views I have elsewhere recorded at great length.
The genetic relations subsisting amongst the Gyrodactyles have given
rise to much controversy. Observing the singular mode of reproduction in
_G. elegans_, Von Siebold arrived at the conclusion that Gyrodactyles in
general were only nurse-forms of some higher organism, and he pointed
out, with undeniable accuracy, all the birth-stages of the young
one as it apparently pullulated within the parent and subsequently
emerged an almost perfect Gyrodactyle. Von Siebold also remarked that
the so-called “daughter,” at the time of birth, nearly equalled the
“parent” in respect of size, whilst, moreover, it contained within
its interior another very young Gyrodactyle, or, in other words, a
“grand-daughter.” Van Beneden interpreted these facts very differently.
I have myself noticed the second generation, or daughter, to contain
in its interior evidences of a third generation. This I observed
in specimens obtained from the tails of Gasterostei caught in the
Serpentine, Regent’s Park. Indications of the third progeny were seen
whilst the daughter still resided within the body of the nurse-parent,
and the so-called grand-daughter became much larger immediately after
birth. In one instance the “daughter” commenced showing herself by a
slight bulging at the centre of the parent’s body, whilst the integument
of the latter yielded on all sides of the bud-like projection, and in
such a manner as to convey the idea of a vaginal opening. There was an
evident struggle on the part of the young one to free itself from the
so-called parent envelope, but the tissues showed no signs of injury. On
partial protrusion it was seen that the budding portion corresponded
with the centre of the daughter’s body, and this, in a little while,
assumed the aspect of a semicircular band. Subsequently the upper end
became detached, the freed extremity being now recognised as the head.
An interval elapsed before the broad posterior end of the animal could
be disengaged, but immediately after this was effected the sides of
the parent envelope closed in upon the opening, and all that remained
was a small cavity or sac, indicating the position recently occupied
by the daughter. Altogether the process occupied about five minutes. I
carefully compared the so-called “parent” with the “daughter,” but in
regard to size I can scarcely say which was the larger of the two. As
before hinted, Van Beneden demurs altogether to Von Siebold’s views. He
does not admit the parent to be a kind of “nurse,” he does not consider
the primary young one to be a “daughter,” and, consequently, he does
not regard the embryo seen within the latter as a “grand-daughter.”
Van Beneden says:--“According to our researches there is here a false
interpretation; the little daughter is lodged within the side of its
pretended mother, and not in its interior; instead of being its mother,
it is its sister; there is a difference of shape because there is a
difference of age; the Gyrodactyles are viviparous, and as among the
Trematodes the eggs are formed one by one, one embryo is scarcely formed
when another commences its evolution, and the egg-deposition is effected
even whilst the embryo is being produced. The Gyrodactyles are therefore
viviparous worms, which beget a single embryo at a time, as those of
the trematode group, to which they are allied, beget a single egg at a
time, and before the first embryo is expelled another is already partly
developed. There, we believe, lies the correct interpretation of that
phenomenon; instead of a bud it is an embryo, which has escaped from
an egg. Here, therefore, we have no phenomenon of alternate generation
or of digenesis, as Von Siebold supposes, but a simple viviparous
reproduction.”
Passing on to notice the cestodes of fishes, I may remark that they
often display characters very distinctive from those inhabiting
birds and mammals, being commonly furnished with special tentacular
hook-appendages employed as supplementary organs of boring and
anchorage. In the cartilaginous sharks and rays these cestodes are
remarkably abundant, and in certain osseous species they are scarcely
less frequent. The only noteworthy kinds of fish which are commonly
free from the invasion of tapeworms are the sturgeons, blennies,
gobios, mullets, sparoids, and Sciænæ. Some few of them are infested by
_Ligulæ_, _Caryophyllæi_, &c. Cuttle fishes harbor a great variety of
tapeworm-larvæ, forming one of the chief sources whence sharks and rays
obtain the same parasites destined to arrive at sexual maturity within
their own bodies.
[Illustration: FIG. 80.--Section of the strobile of _Bothriocephalus
proboscideus_. Magnified. After Busk.]
Among the most interesting cestodes of fishes we may reckon the
pit-headed tapeworms and their allies (Bothriocephalidæ). One of the
most common species is _Both. proboscideus_ which is found, often in
considerable numbers, lodged within the pyloric appendages of the
salmon (_Salmo salar_ and _S. hucho_). It acquires a length of two
feet. When in large numbers it cannot fail to prove injurious to the
bearer. In this connection also must be mentioned _B. nodosus_. In the
adult state this worm infests a great variety of water-birds (herons,
gulls, and divers), but in the young or sexually-immature tænioid
condition it is a frequent inhabitant of sticklebacks (_Gastereosteus
aculeatus_ and _G. pungitus_), being also found in the salmon and
in the bull-head, or father-lasher (_Cottus scorpio_). The immature
tapeworm was formerly considered a separate species (_B. solidus_).
Some years back Creplin discovered the connection subsisting between
the two forms, and re-described the species in its two conditions under
the name of _Schistocephalus dimorphus_, but it was reserved for Von
Siebold to explain the full nature of this relationship. In his essay
on “Tape and Cystic Worms” he shows that it is not until the worm
reaches the intestine of the ultimate host that its segments acquire
sexual completeness. As Von Siebold observes, “the extent of development
in each individual will be found to be in proportion to the time the
parasite has passed in the bird’s alimentary canal after its passive
immigration.” A similar instance, it is added, “occurs in the case of
the _Ligula simplicissima_, infesting the abdominal cavity of various
species of carp, whose sexual organs are, and remain, undeveloped as
long as the worm resides within the fish; whilst, when the latter is
eaten by ducks, divers, waders, and other water-fowl, the entozoon
being thus conveyed into their intestine, it attains perfect sexual
development. In the older helminthological works the sexually-mature
_Ligula simplicissima_ is described under various specific names (_L.
sparsa_, _L. uniserialis_, _L. alternans_, _L. interrupta_).” These
results have been confirmed by later observers, but it is now usual
to recognise the sexually-mature worm as the _Ligula monogramma_ of
Creplin. In 1876 Dr Duchamp published his beautiful memoir on this
subject, treating the entire question exhaustively and adding important
experimental details. M. Duchamp gives a list of about twenty species
of fish that are infested by the immature worm, and amongst these the
_Cyprinidæ_ play by far the most conspicuous part. M. Duchamp has
recorded a fatal piscine epizoöty amongst tenches (_Tinca vulgaris_),
occurring in the ponds of La Bresse. This is produced by _Ligula
simplicissima_, which escapes by an aperture formed near the vent of
the infested fish. M. Duchamp also gives important anatomical and
embryological details, but the especially interesting part of his
memoir refers to his feeding experiments, seven in number. He succeeded
in rearing _L. monogramma_ in the domestic duck, by feeding this bird
with examples of _L. simplicissima_ obtained from the abdomen of the
tench (_Tinca vulgaris_). The interest of these experiments does not
cease here, since they afford a probable clue to the source of human
_Bothriocephali_, which in nearly all essential points of structure
correspond with the Ligules. As remarked in the first part of this work,
Leuckart long ago pointed to the Salmonidæ as probably furnishing the
intermediate host of this worm; and he disproved the views of Knoch, of
Petersburg, who thought he had reared _Bothriocephalus latus_ in the dog
in a direct manner. I have already called attention to the opinion of
Dr Fock, of Utrecht, who thinks the human bearer may become infested by
the consumption of the little fresh-water bleak (_Leuciscus alburnus_).
From the observations of Dr Bertolus, it is extremely probable that our
_Bothriocephalus latus_ is the sexually-mature condition of _Ligula
nodosa_ infesting the abdominal cavity and pyloric appendages of the
common trout (_Salmo trutta_).
Another cestode of general interest is the _Tricuspidaria_
(_Triænophorus_) _nodulosus_, infesting many of our fresh-water fishes.
It varies in length from one to two feet. The segmentation of the
strobila is very indistinct, but the reproductive organs occur at
regular intervals. All parts of the body are extremely contractile,
especially the head. The tricuspid hooks support thin chitinous laminæ,
which connect the two lateral horns of each hook to the central
apophysis. The object of this arrangement is to afford additional
security to the prong-like processes. Van Beneden appears to think it
an error that the cusps of the hooks should have been figured in ‘Règne
Animal’ as directed forwards, and he has drawn the hooks with the points
downwards. In regard to the calcareous corpuscles, narrow vessels may
be easily recognised passing off continuously from the capsules in
closing the particles. These vascular prolongations are single, having
their course directed towards the epidermis; doubtless they open at the
surface, but I did not detect any aperture. I have figured the tubes in
my ‘Entozoa’ (p. 132). Dr Guido Wagener figures similar structures as
occurring in _Cercaria macrocerca_.
Various species of _Tetrarhynchus_ dwell in the bodies of sharks and
rays, whilst their larvæ inhabit fishes on which the plagiostomi
feed. Immature tetrarhynchs occur in cuttle-fishes, but they are most
abundant in such fish as the cod, haddock, turbot, whiting (Fig. 81),
flounder, sole, gurnard, mackerel, mullet, and conger-eel. A tænioid
scolex constantly infests the muscles and viscera of the great sunfish.
The tetrarhynchs differ from one another as regards the form of their
proboscides and the relative number and disposition of the hooks. I
must refer to my ‘Entozoa’ for a full description, with figures, of
a larval tetrarhynch from the wall of the intestine of a haddock.
Some Tetrarhynchi exhibit a very complex armature, as may be seen
in _Tetrarhynchus longicollis_ infesting the tope or penny dog-fish
(_Galeus vulgaris_). In this species the hooks are uniform in size, and
arranged in spirally disposed circles carrying from twenty to thirty
hooks each. In the tetrarhynch from the whiting the hooks show much
irregularity both as regards size and arrangement. A remarkable scolex
infests the sun-fish (_Orthagoriscus mola_); it is a true tetrarhynch,
but has been variously classed. According to view all the following
titles refer to this parasite:--_Gymnorhynchus reptans_, Rudolphi;
_G. horridus_, John Goodsir; _Acanthorhynchus reptans_, Diesing;
_Bothriorhynchus continuus_, Van Lidth de Jeude; _Bothriocephalus
patulus_, Leuckart; _Acanthocephalus elongatus_, Rudolphi; _A.
macrourus_, Bremser; _Floriceps saccatus_, Cuvier; _F. elongatus_,
Blainville; _Scolex gigas_, Cuvier; _Tetrarhynchus reptans_, Cobbold.
[Illustration: FIG. 81.--Portion of the proboscis of a scolex of
_Tetrarhynchus_ infesting _Merlangus vulgaris_. Magnified. After Busk.]
Five or six examples of the sunfish have been examined by me in the
fresh state, all of them being infested by tetrarhynchs. In the fish
here drawn (fig. 82) the liver and lateral muscles were extensively
tunnelled by the parasite. In all instances the anterior part of the
worm was found surrounded by a thick, clear, transparent cyst, which
gradually diminished in thickness towards the tail. When liberated from
its investing capsule the head of the worm presents a quadrilateral
figure, each lateral half being furnished with a bipartite facet. The
retractile boring organs are club-shaped, each supporting about 1600
hooks. Nearly all the hooks display a uniform length and thickness, but
at the lower part of each proboscis there are two conspicuous circles,
the hooks of which are at least twice as large as the others. The
joints of the immature strobile are well formed, but exhibit no trace
of sexual organs. If it be asked “what is the object of this perpetual
tunnelling,” and “does the boring cause suffering to the host,” I
reply:--“The object of tunnelling is apparently twofold; first, that
the parasite may constantly obtain fresh nourishment; and secondly,
that it may acquire another residence.” It furnishes an example of
a parasite perpetually striving to perform an act which it cannot
accomplish; for, in order to arrive at sexual maturity, it must wait
until the sunfish is devoured by a shark. In regard to the question as
to the boring action giving rise to pain, one cannot, of course, speak
with absolute certainty. When there are many parasites occupying the
liver, or other important viscera, then, doubtless, they create pain,
and cause decay of the organs infested; thus they enfeeble the vital
powers of the host. At such a time the sunfish would be easily overcome
by its natural enemies, and be the first to succumb in the struggle for
existence. These wandering tetrarhynchoid scolices never escape the body
of the intermediate host until they are passively transferred into the
alimentary canal of the ultimate entertainer. In the sharks and rays
they acquire sexual maturity. From these animals the proglottides pass
into the water in the ordinary way. The ova are subsequently swallowed
by sunfishes and other intermediate hosts, within whose stomachs the
six-hooked embryos are liberated, and the scolices become developed in
the ordinary manner. As obtains in _Cysticercus fasciolaris_ of the
mouse the scolex of _Tetr. reptans_ becomes tænioid. I have seen the
liver of an adult sunfish so infested by these parasites that the whole
organ might be fitly described as a mere bag of worms, the immature
strobiles being inextricably coiled together and defying separation. One
of the parasites which I removed from this particular fish is preserved
in the Hunterian Collection.
[Illustration: FIG. 82.--_Tetrarhynchus reptans_. 1, Reduced figure of a
sunfish, showing the worms _in sitû_; 2, head of a worm in its capsule;
3, tænioid scolex; 4, section of the immature strobile, 5, proboscis; 6,
row of hooks; 7, 8, large and small hooks (magnified 260 diameters); 9,
head of the scolex viewed from above. Original.]
In reference to the nematoids of fishes I can say but little. They are
excessively abundant; sexually-immature filariæ being found in almost
every marine fish that one examines. Even at our dinner and breakfast
tables nothing is more common than to observe the little _Filaria
piscium_ spirally coiled within the tissues of herrings, haddocks,
cod-fish, and whiting. All the sexually-immature nematoids are, as it
were, waiting to be passively transferred to their ultimate hosts. These
final bearers are usually either fishes, birds, cetacea, or seals.
Amongst fresh-water fishes the _Cucullanidæ_ play an important rôle.
These parasites closely resemble the strongyloid _Sclerostomata_, but
the absence of a true bursa seems to justify their separation into a
distinct family. In most of them the body is truncated in front and much
narrowed or drawn out posteriorly. The head is, broad and globular,
and furnished with a powerful muscular pharynx. The mouth is seldom
round; it is often subterminal, opening by a transverse slit. The tail
of the male is recurved, and usually supplied with membranous winged
appendages; sometimes there is a pre-anal sucking disk. In the female
the tail is simple, and more or less sharply pointed.
[Illustration: FIG. 83.--_Cucullanus foveolatus._ Female. From the
plaice (_Platessa vulgaris_). Magnified. After Busk.]
The facts relating to the development of these parasites are especially
interesting as having afforded Leuckart and Fedschenko a clue to what
obtains in the guinea-worm (_Dracunculus_). The Cucullanus of the perch
(_C. elegans_) is a viviparous species. The embryos are supplied with
little boring teeth, or styles, which enable them to perforate the
bodies of entomostracous crustaceans. Having in a direct manner gained
access to the perivisceral cavity of _Cyclops_, they remain coiled
within the intermediate bearer until it has been pursued, captured,
and transferred to the stomach of the ultimate or piscine host. Once
liberated within the stomach of the fish the young _Cucullani_ soon
acquire sexual maturity.
[Illustration: FIG. 84.--1, _Echinorhynchus angustatus_ (natural
size and enlarged); 2, _Echinorhynchus nodulosus_ (natural size and
enlarged), with (3) two eggs (magnified 1000 diameters). Both species
from a trout. After Busk.]
The acanthocephalous _Echinorhynchi_ are very abundant in fishes.
They also, like the _Cucullani_, require a change of hosts in order
to ensure the continuance of the species. No less than six species of
Echinorhynchi are known to infest the trout (_Salmo fario_). As many
as four species likewise infest the eel (_Anguilla_); the same number
of distinct forms being also found in the turbot (_Rhombus_) and ling
(_Lota_), whilst three species may be met with in the common sole
(_Solea_). What we at present know respecting the mode of development
of Echinorhynchi infesting fishes is principally due to the researches
of Leuckart. Some years back Dr Guido Wagener supplied admirable
illustrations of the eggs and embryos of Echinorhynchi, but he was
erroneously led to conclude that the larvæ were developed in a direct
manner. The notion of a simple metamorphosis was entirely disproved
by the experiments of Leuckart, who found the growth and development
of the young to be accompanied by a true alternate generation. He
showed this to obtain in _Echinorhynchus proteus_, a species abundant
in the trout and in many other fresh-water fishes. The embryo of
this parasite is broad and obliquely truncated at the ventral surface
anteriorly, being gradually narrowed to a blunt point posteriorly, and
at the front part, on each side of the middle line, there are five or
six spines biserially disposed. Similar characters are seen in _E.
filicollis_. Prof. Leuckart introduced a number of eggs into a vessel
of water containing several small crustaceans (_Gammarus Pulex_). These
little animals readily swallowed the ova, and in a few days the embryos
were found emerging from their shells, boring their way through the
intestinal walls, then passing into the general cavity of the body, and
even into the appendages themselves. During the next fourteen days the
embryos within the Gammari exhibited an increase of size; and in course
of the third week a further metamorphosis caused the embryos to assume
the readily recognisable characters of a young _Echinorhynchus_. Thus,
in Leuckart’s own words, “the ultimate animal arises in the interior of
the primordial body, by a process which presents so close an analogy
with the production of an embryo, and, consequently, with the act of
generation, that one feels inclined at once to identify it with such an
act, and therefore, also, to regard the _Echinorhynchus_ as exhibiting
an alternation of generation in its mode of development rather than a
metamorphosis.”
The young _Echinorhynchus_ afterwards grows rapidly, its several
internal organs, proboscideal sac, and muscular apparatus, gradually
coming into view. At last the young entozoon completely fills the
interior of the embryo, the latter having scarcely undergone any
change, and still remaining, of course, within its crustacean host.
What may be regarded as even more extraordinary is the circumstance
that the embryonic body next becomes firmly adherent to the young
_Echinorhynchus_, thus ultimately forming the true integument of the
adult _Echinorhynchus_. The original skin of the embryo, however,
is cast off “as soon as the _Echinorhynchus_ occupies the whole
interior of the embryo.” After this the sexual differences become
clearly established. Leuckart remarks that the passage of the young
Echinorhynchi into their ultimate host is probably unattended by any
striking changes, whilst the metamorphosis of the embryo, as thus
far detailed, occupies a period of about six weeks. In general the
crustacean hosts appear to suffer little from the borings of the embryo
parasites, but when the latter have assumed the Echinorhynchus-condition
and happen to be particularly numerous they not unfrequently prove
fatal to the unsuspecting Gammari. After their transference to the
intestine of the ultimate host a period of about one week more is
required for the completion of their development.
From the large number of species of _Echinorhynchi_ infesting our
fresh-water fishes, they present quite a feature of piscine parasitism.
Almost every perch, chub, carp, pike, barbel, bream, or roach that
one opens is found to have its intestines occupied by parasites which
exhibit a light yellow color. These are Echinorhynchi, the common forms
being _E. proteus_, _E. angustatus_ (Fig. 84, No. 1), _E. clavæceps_,
_E. globulosus_, and _E. tuberosus_. In the Salmonidæ, besides several
of the above, we may also find _E. clavula_, _E. fusiformis_, and _E.
pachysomus_. As a group these parasites are more attractive looking than
most other helminths, and they will well repay the zoological collector.
The species infesting marine fishes are almost as numerous as those
found in fresh-water hosts.
BIBLIOGRAPHY (No. 59).--(Anonymous), “Note by ‘An Inquirer’ respecting
Worms in Fish,” in the ‘Lancet,’ March 7, 1868, p. 336.--_Baer, K. E.
von_, “On the Tapeworms found in the Waters of the Pregel by Linneus,”
from the German, in ‘Edin. New. Phil. Journ.,’ 1829, p. 374, and in
the ‘Edin. Nat. and Geo. Sci. Journ.,’ 1829-30, p. 311; also from the
‘Trans. of Nat. Soc. of Dantzig,’ in the ‘Lancet,’ 1829.--_Badcock_;
see _Slack_.--_Baird_, ‘British Entomostraca,’ London, 1850.--_Beneden,
J. P. van_, “Les vers cestoides,” ‘Mém. de l’Acad. Roy. de Belg.,’ tom.
xxv, 1850.--_Idem_, ‘Mém. sur les vers intest.,’ Paris, 1858.--_Idem_,
“On Echinobothrium,” in ‘Bull. de l’Acad. de Brux.,’ 1849.--_Idem_,
(with Hesse), ‘Rech. sur les Bdellodes ou Hirudinées et les Trématodes
marins,’ 1863-65.--_Idem_, ‘Rech. sur les Turbellaries,’ 1861.--_Idem_,
“On a new Lerneonema,” ‘Bull.,’ l. c., 1851, and in ‘L’Institut,’
1851.--_Bertolus_, ‘Mém. sur le développement du _Dibothrium latum_
(Bothriocéphale de l’homme),’ App. to Dr Duchamp’s work quoted
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“On the occurrence of Gyrodactylus on Sticklebacks,” ‘Proc. Linn. Soc.,’
1861.--_Brullé_, “Note on the Reproduction of Ligula,” from ‘Comptes
Rendus,’ in ‘Ann. Nat. Hist.,’ 1855.--_Chatin_, ‘On _Amphibdella
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Fluke-larvæ from Coregonus,” in ‘Bull. de la Soc. Vaud. des Sci.
nat.,’ tom. iii.--_Claparède, E._, “Ueber die Gattung Tetracotyle,”
&c., in ‘Zeitsch. f. wiss. Zool.,’ 1857, s. 99 _et seq._--_Cobbold_,
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1862.--_Idem_, “Notes on the Calcareous Corpuscles of Tricuspidaria,”
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Pentastoma,” _ibid._, 1859.--_Idem_, “Note on _Gyrodactylus elegans_,”
_ibid._, 1862; see also Wedl.--_Idem_, “On _Distoma clavatum_ from the
Sword-fish,” ‘Proc. Linn. Soc.,’ 1867 (Zool. Sect., p. 200).--_Idem_,
“Tapeworms in Trout,” letter to the ‘Field,’ July 26, 1873; see also
F. Francis (below).--_Idem_, “Remarks on the Entozoa and Ectozoa of
Fish,” the ‘Veterinarian,’ Oct., 1867, p. 671.--_Idem_, “On _Agamonema
crenilabri_,” in ‘Science Gossip,’ 1876; see W. W. Wilson.--_Idem_, in
‘Linn. Trans.,’ 1858.--_Idem_, ‘Note on Parasites from the Wolf-fish
(Annarhicas) and Lump-sucker (Cyclopterus), collected by Mr Devis’ (l.
c., Bibl. No. 57).--_Idem_, “Descr. of the Scolex of a Tetrarhynchus,”
in a paper on ‘Parasite Larvæ,’ ‘Intell. Observer,’ 1863.--_Idem_,
“Synopsis of the Distomidæ,” ‘Proc. Linn. Soc.’ (Zool. Div.),
1860.--_Idem_, “Remarks on _Bothriocephalus latus_, in relation to Dr
Fock’s supposition that the Bleak (_Leuciscus alburnus_) is concerned in
its Production,” the ‘Veterinarian,’ July, 1878.--_Cornalia, E._, ‘Sopra
una nuova specie di Crostacei Siphonostomi (_Gyropeltis doradis_),’
Milano, 1859.--_Coughtrey, M._, “On the absence of Tapeworm in the
Salmon-trout of New Zealand,” letter to the ‘Otago Daily Times,’ dated
from the Otago University, Dec. 6, 1875.--_Diesing_, ‘Vierzehn Arten
von Bdellideen,’ Wien, 1858; see also ‘Revisions,’ quoted in Bibl.
No. 58.--_Donnadieu, A._, “Étude sur les Ligules,” in ‘Archives Zool.
Expériment.,’ 1876.--_Duchamp, G._, ‘Recherches anat. et physiol. sur
les Ligules,’ Paris, 1876; see also Bertolus.--_Fock_, ‘The Bleak as a
source of the Broad Tapeworm.’ See Cobbold.--_Francis, F._, “Tapeworm in
Fish” (with report by myself), in the ‘Field,’ June 28, 1873.--_Idem_,
in the ‘Field’ for July 12, 1873.--_Garsin_, ‘Histoire de l’Acad.
des Sci.,’ Paris, 1730, p. 44.--_Goodsir, J._, “On _Gymnorhynchus
horridus_, a new Cestoid Entozoon,” ‘Edin. New Phil. Journ.,’ p. 9,
1841.--_Houghton, W._, “On the occurrence of _Gyrodactylus elegans_ in
Shropshire,” ‘Ann. Nat. Hist.,’ 1862.--_Huxley_, “Note on Gyrodactylus,”
‘Proc. Roy. Inst.,’ April 20, 1852, and ‘Edin. New Phil. Journ.,’
1852, p. 172.--_Knoch, J._, ‘Entwickelungsgeschichte d. _Both.
proboscideus_,’ 1862.--_Knox, J. F._, “Note respecting the occurrence
of a peculiar Microscopic Entozoon in the Textures of the Herring,”
‘Lancet,’ 1838.--_Kölliker_, “Zwei neue Distomen,” ‘Ber. v. d. K.
Zoot. Anstalt zu Würzburg,’ 1849.--_Idem_, ‘Ueber Tristoma,’ _ibid._,
1849.--_Leidy, J._, “Notice of a Tetrarhynchus (_T. tenuicaudatus_)
in the Remova;” ‘Proc. Acad. N. S. Philad.,’ Oct. 15, 1878; and in
‘Ann. Nat. Hist.,’ Feb., 1879.--_Leydig_, “Ueber Argulus,” ‘Sieb.
und Köll. Zeitsch.,’ 1850.--_Maddox, R. L._, “Some Remarks on the
Parasites found in the Nerves (and other parts) of the Common Haddock
(_Morrhua æglefinus_),” ‘Trans. of the Roy. Micr. Soc.,’ 1867, p.
87.--_Menzies_, ‘Linn. Trans.,’ 1790, p. 187.--_Miescher_, “On _Filaria
piscium_,” &c., in ‘Excerpta Zoologica,’ communicated by Dr Frances,
in ‘Ann. Nat. Hist.,’ 1842.--_M’Intosh, W. C._, “Notes on the Food
and Parasites of the _Salmo salar_ of the Tay,” ‘Proc. Linn. Soc.,’
1863; repr. in the ‘Zoologist,’ Feb., 1864.--_Müller, J._, “Note on
a Parasitic Formation (Gregarina) in the Pike, with a statement from
his ‘Neurologie der Myxinoiden,’ that _Diplostomum rachineum_ is to be
found alive under the cerebral membranes of _Petromyzon fluviatilis_,”
from ‘Müller’s Archiv,’ in ‘Micr. Journ. and Struct. Record,’ p. 20,
1842.--_Nardo_, in ‘Heisinger’s Zeitsch.,’ 1827, s. 68, and in ‘Isis,’
1833, s. 523.--_Olsson, P._, “Researches on the Flukes and Tapeworms
chiefly of Marine Fishes,” ‘Entozoa, iakttagna hos Skandanaviska
Hafsfiskar,’ Lund (aftr. ur ‘Lunds Univ. Årsskrift,’ tom. iii, iv),
1867-68.--_Owen_, ‘Zool. Soc. Trans.,’ 1835, p. 382.--_Pallas_,
‘Spicilegia Zoologica,’ fasc. x, p. 18, 1774.--_Siebold, C. von_,
‘Band und Blasenwürmer,’ s. 41, Huxley’s edit., p. 32.--_Idem_, “On
_Diplozoon paradoxum_,” from ‘Zeitsch. f. wiss. Zool.’ (by Huxley), in
‘Ann. Nat. Hist.,’ 1851.--_Idem_, “Ueber den Generationswechsel der
Cestoden nebst einer Revision der Gattung Tetrarhynchus,” ‘Zeitschr. f.
wiss. Zool.,’ 1850, s. 198.--_Idem_, “Gyrodactylus, ein ammenartiges
Wesen,” _ibid._, 1849.--_Slack, H. J._, “On _Bucephalus polymorphus_,”
in ‘Monthly Microsc. Journ.,’ April, 1875, p. 141.--_Van Beneden_ (see
Beneden).--_Verrill, A. E._, “On the Parasitic Habits of the Crustacea,”
from ‘American Naturalist,’ in ‘Scientific Opinion,’ Aug. 4, 1869, p.
185.--_Idem_, “New Flukes (_Tristoma læve_ and _T. cornutum_) from
the Mouth and Gills of _Tetrapturus albidus_,” ‘American Journ. of
Science,’ p. 40, 1875.--_Von Baer_ (see Baer).--_Von Siebold_ (see
Siebold).--_Wagener, R. G._, “Helminth. Bemerkungen,” in ‘Sieb. und
Köll. Zeitsch.,’ 1857.--_Idem_, “Enthelminthica,” ‘Müller’s Arch.,’
1851.--_Idem_, “Ueber Eingeweidewurm (Amphiptyches) in _Chimæra
monstrosa_,” ‘Müll. Arch.,’ 1852.--_Idem_, ‘Beiträge zur Entw.-Gesch.
der Eingeweidewürmer (Preisschrift),’ 1857.--_Wedl_, “On Gyrodactylus”
(see reference to my paper on ‘_G. elegans_’), ‘Quart. Journ. Micr.
Sci.,’ 1862; trans. from his ‘Anhang,’ “Ueber die Gattung Gyrod.,” to
‘Anat. Beobachtungen ueber Trematoden,’ Wien, 1858.--_Idem_, ‘Hæmatozoa
in Fishes,’ &c. (l. c., Bibl. No. 58).--_Wigham, R._, “Note on
_Holostomum cuticola_ from Roach and Bream,” ‘Ann. Nat. Hist.,’ p. 235,
1851.--_Wilson, W. W._, “On a Parasitic Worm infesting a Marine Fish
(_Crenilabrus rupestris_),” in ‘Science Gossip,’ Jan., 1876.--_Yarrell,
W._, “Note on _Tristoma coccineum_,” in his work on ‘Brit. Fishes,’ vol.
ii, p. 353, 1836.
PART IV (EVERTEBRATA).
[Illustration: FIG. 85.--_Sphærularia bombi._ Showing the supposed male
_in sitû_. After Lubbock.]
Since a large proportion of all those helminths that require a change
of hosts must needs pass into the bodies of insects, crustaceans,
mollusks, or other evertebrated animals, it is evident that these
lower creatures are almost as liable to be infested by parasites as
the vertebrates themselves. As a rule, no doubt, the parasitic forms
infesting individual evertebrated hosts are not numerous; nevertheless
the water-snails form a noteworthy exception. Thus, some ten different
species of parasite are found either in or upon the common _Planorbis
corneus_; whilst _Lymnæus stagnalis_, _Paludina vivipara_, and _P.
impura_, each support at least a dozen species. Of course, the parasites
are not sexually mature, since nearly all of them are _Cercariæ_ or
larval trematodes. Snails, oysters, mussels, whelks, and other mollusks
afford harbour and anchorage to a variety of parasites and messmates;
but, fortunately, few or it may be none of the strictly human parasites
require to pass through these intermediate bearers. _Distoma crassum_
is possibly an exception. Save the cuttle-fishes, not many evertebrated
animals are infested by sexually-mature worms. One of the most notable
exceptions is that of a nematoid infesting bees. This worm was known
to John Hunter, who spoke of it as “the animal that breeds in the
humble bee.” In the year 1836, M. Léon Dufour first applied the term
_Sphærularia_ to this remarkable worm, which he discovered in the
abdominal cavities of two species of bee (_Bombus terrestris_ and
_B. hortorum_). The worm was subsequently found by Von Siebold in
two other species of bee (_B. muscorum_ and _B. sylvarum_), but it
remained for Sir John Lubbock to demonstrate that this parasite not
only infests these insects, but also _Bombus lucorum_, _B. lapidarius_,
_B. pratorum_, _B. subterraneus_, and _Apathus vestalis_. I possess
specimens from _Vespa vulgaris_ and _V. rufa_. Sir J. Lubbock and Mr.
Cole have separately given full anatomical descriptions of the worm.
According to Lubbock the so-called female is about an inch in length,
of a whitish color, and 1/15″ in thickness, being bluntly pointed at
either extremity. _Sphærularia_ is everywhere covered by small warts
or button-like projections, in all numbering about 800. The warts are
transparent, each, according to Lubbock, projecting from 4/1000″ to
6/1000″ above the general surface of the integument. There is neither
mouth, œsophagus, intestine, nor anus; but in their place a large fatty
mass or _corpus adiposum_. Sir J. Lubbock remarks that this peculiar
organ “is homologous, not with the whole intestinal canal of nematodes,
but only with the intestine; and we find, in fact, that in Gordius the
œsophagus is very short, and opens at once into the anterior end of the
_corpus adiposum_; so that to pass from this genus to _Sphærularia_ it
would be necessary to shorten the œsophagus a little more, and then the
wall of the _corpus adiposum_ would be immediately attached to that of
the body. So far, therefore, as concerns the _corpus adiposum_ and the
œsophagus, _Sphærularia_ agrees neither with Gordius nor Mermis, nor,
indeed, with one more than the other; since, if it agrees with _Mermis
albicans_ in the double series of large fat cells, it has no œsophagus,
and in this respect more nearly resembles Gordius.” The reproductive
organs consist of a single ovary, uterus, and terminally situated vulva.
These organs in the full-grown females contain ova in all stages of
development up to the condition of advanced yolk segmentation; but it
does not appear that embryonic formation takes place whilst the eggs
are still _in utero_. “The young animals are born soon after the eggs
are laid. They are about 1/60″ in length, and 1/2500″ in diameter at
the broadest part. Before Sir J. Lubbock conducted his inquiries the
so-called male appears to have been overlooked. The male, if male it be,
is extremely minute; that is to say, about 28,000 times smaller than
the female.” Notwithstanding this very circumstantial account based on
Lubbock’s determinations, Schneider has sought to show that the facts
have been entirely misinterpreted. What Lubbock regards as the male
worm is, in Schneider’s opinion, a female, whilst the so-called female
is nothing more than a gigantic prolapsed uterus which has become many
thousand times larger than the body of the worm whence it proceeded.
It must be allowed that Schneider’s description and accompanying
figures are very convincing. When revising the entozoa of the Hunterian
Collection in 1866 I explained the specimens and dissections in
accordance with Lubbock’s views. In the following year Prof. Huxley
in his College Lectures supported the view of Schneider, but in his
recently published manual the opinions of the Berlin helminthologist are
not so much as alluded to.
Another point of special interest in connection with the parasites of
insects concerns the development of _Mermis albicans_. At or near the
time of the maturation of the ova, the parent worm, hitherto lodged
within the body of some insect, buries itself in the soil. It commences
its migration by boring its way out of the body of the host. Some
difference of opinion exists as to the condition of the parent at the
time of its wandering, for Von Siebold asserted that it quitted its
parasitical mode of life “in order to become sexually mature away from
the animal” infested; whereas Van Beneden states that the embryos are
always formed at the time of the wandering.
From Von Siebold’s experiments it would appear that incompletely
developed Mermes can become mature whilst still in the soil; but
the normal condition requires the wandering to commence, as we have
said, at or near the full time of embryonal development. The embryos
are reproduced viviparously, and being set free, they pass a certain
period of their existence in the soil. Here they grow rapidly, acquire
sexual organs, and subsequently seek to “gratify their immigrative
propensities,” as Von Siebold says, by selecting and penetrating the
soft-bodied larvæ of lepidopterous and other insects. This entrance they
accomplish by means of a sharply-pointed dentule or boring stylet, which
at the time of disuse is concealed within the head. Having once gained
access to the host they remain within its body until the caterpillar has
become transformed into the perfect butterfly, or until their own sexual
maturity is completed. Van Beneden thinks it probable that the males
quit the host some time before the females, a view which, if correct,
might alone account for the comparative scarcity of the males. According
to Von Siebold, sexual congress occurs before the entrance of the
worm into the caterpillar. This observation agrees with the generally
admitted fact that hitherto no male Mermes have actually been detected
in the bodies of insects. The Gordii, like Mermes, become free in damp
earth and penetrate the bodies of certain insects or their larvæ. Some
of them gain access to fishes. Like the free nematodes (_Anguillulidæ_),
many of the Gordii will survive complete desiccation. The eggs of the
mature worms are deposited in long agglutinated chains in water or damp
situations.
I must conclude. In the body of this work will be found many notices
of insect parasites that are awaiting transference to some vertebrate.
I need only allude to the rôle of the mosquito, to that of the
louse of the dog, and especially to that of the little myriapod
(_Glomeris_) which, like the common glow-worm (_Lampyris_), possesses
phosphorescent properties. I mention this again partly in correction of
an entomological error (at p. 296) which escaped me at the time of going
to press. Leidy has described a mature nematode (_Ascaris infecta_)
from _Passalus cornutus_, and numerous Filariæ are known to infest
insects (_Blatta_, _Forficula_, _Phosphuga_, &c., &c.). From an earwig I
obtained a filaria nearly five inches in length.
We have seen that the larvæ of _Dracunculus_, _Cucullanus_, as well as
those of other important nematodes, dwell in bodies of entomostracous
crustacea, whilst those of _Echinorhynchus_ attack the Gammari and
their allies. The well-known _Udonella caligorum_ attaches itself to
crustacea that are themselves parasitic.
As many of the so-called free nematodes live in the slime of animals,
Villot is of opinion that no very distinct line of demarcation can
fairly be drawn between the parasitic and free species. This work,
however, having dealt only with genuine parasites, I have purposely
omitted any detailed account of the so-called free nematoids. I mention
this lest it should be supposed that I had shown a studied neglect
of the more or less remarkable labours of Bütschli, Bastian, Eberth,
Linstow, Marion, Villot, Claus, De Man, Carter, and many others.
BIBLIOGRAPHY (No. 60).--_Bastian, H. C._, “Monograph on the
Anguillulidæ, or free Nematoids, marine, land, and freshwater, with
description of 100 new species,” ‘Linnean Trans.’ for 1865, vol.
xxv, p. 73.--_Idem_ (see Bibliog. No. 2).--_Idem_, “Free Nematoids,”
being an article in the ‘Popular Science Review’ for 1868, vol. vii,
p. 163.--_Brady, G. S._, ‘Monograph of the free and semiparasitic
Copepoda,’ London, 1878.--_Bütschli, O._, “Untersuchungen ueber
freilebende Nematoden und die Gattung Chætonotus,” ‘Sieb. und Köll.
Zeitschrift,’ 1876.--_Carter, H. J._, “On a Bisexual Nematoid Worm
which infests the common House-fly (_Musca domestica_),” ‘Ann. Nat.
Hist.,’ 1861, and in the ‘Bombay Med. and Phys. Soc. Trans.,’ new
series, 1860.--_Claparède_ (see Panceri).--_Claus, C._, ‘Beobachtungen
ueber d. Organis. und Fortpflanz. v. _Leptodera appendiculata_,’
1869.--_Cobbold_, “Note on Insect Parasites,” in ‘Rep. of Entomological
Club,’ in the ‘Midland Naturalist,’ March, 1878, p. 80.--_Cole, W._,
“Remarks on a Parasite of Humble Bees,” in ‘Journal of the Quekett
Microscopical Club,’ 1875.--_Dufour, L._, “Sphærularia,” ‘Ann. des Sci.
Nat.,’ 1836.--_Dujardin_, “On Mermis,” ‘Ann. des Sci. Nat.,’ 2e sér.,
tom. 18, p. 129.--_Eberth_ (see Bibliog. No. 2).--_Garner, R._, “Note on
a Distoma,” in his paper ‘On the Lamellibranchiate Conchifera,’ ‘Trans.
Zool. Soc.,’ 1841.--_Ghaleb, O._, “Observations and Experiments on the
Migrations of _Filaria rhytipleurites_, a Parasite of Cockroaches and
Rats,” ‘Comptes Rendus,’ July 8, 1878, and ‘Ann. Nat. Hist.,’ Aug.,
1878.--_Idem_, “Note sur l’anat. et les migrations de deux Nématoides
parasites, le _Pæcilogaster blatticola et Fil. rhytipl._,” Paris,
1876 (quoted by O. von Linstow).--_Giard, M. A._, “On the parasitic
Isopoda of the genus Entoniscus (infesting Crustacea),” from ‘Comptes
Rendus,’ Aug., 1878, in ‘Ann. Nat. Hist.,’ Otc., 1878.--_Idem_,
“On the Orthonectida, parasitic on Echinodermata and Turbellaria
(Rhopalura),” ‘Ann. Nat. Hist.,’ Feb., 1878.--_Grube, A._, “On Cyclops
as a new Cestoid-bearing Host,” from ‘Zoologisch. Anzeiger,’ Bd. i,
s. 74, in ‘Journ. Royal Microsc. Soc.,’ Nov., 1878, p. 254.--_Hunter,
J._, “Filaria of the Bee,” in ‘Catal. (by Owen) of the contents of the
Mus. Royal Coll. Surg.,’ part iv, fasc. i, p. 37, 1830.--_Kynston_,
“Worms attached to a Grasshopper,” ‘Proc. Ashm. Soc.,’ in ‘Corbyn’s
India Review,’ and in ‘Journ. of Foreign Sci.,’ 1837, p. 172.--_Lima,
J. F. da S._, “Remarks on the _Filaria medinensis_ or Guinea-worm;
on the occurrence of this parasite in the Province of Bahia; and on
its entrance into the human body by drinking water;” trans. from the
Portuguese by Dr J. L. Paterson, and pub. in the ‘Veterinarian’ for
Feb., 1879 _et seq._--_Linstow_, “Helminthologische Beobachtungen,” in
‘Archiv für Naturgeschichte,’ 1876.--_Lubbock, Sir J._, “On _Sphærularia
bombi_,” ‘Nat. Hist. Rev.,’ 1861.--_Idem_, “Notes,” &c., _ibid._, 1864,
p. 265.--_Mason, J. W._, “Note on the Geographical Distribution of
the _Temnocephala chilensis_ (parasitic upon a freshwater crayfish,
_Paranephrops setosus_, in New Zealand),” ‘Annals Nat. Hist.,’
1875, p. 336.--_Marion, A. F._, ‘Revision des Nématodes (&c.),’
Marseilles.--_Maund, B._, “A description of _Filaria forficulæ_,” ‘Rep.
Proc. Linn. Soc.,’ in ‘Zool. Journ.,’ 1832-34, p. 263.--_Meissner_
(see Thomson).--_Owen, R._ (see Hunter).--_Pagenstecher_ (see Bibl.
No. 58).--_Panceri, P._ (e di E. D. Claparède), “Nota sopra une
alciopide parassito dell _Cydippe densa_,” ‘Mem. della Soc. Ital. di
Sci. Nat.,’ 1867.--_Sars_, “Intestinal Worm in an Acaleph.,” from
‘Wiegmann’s Archiv,’ in ‘Ann. Nat. Hist.,’ 1845.--_Siebold, C. J. von_,
in ‘Wiegmann’s Arch.,’ 1835.--_Idem_, in ‘Ray Soc. Rep.’ (by Busk),
1847.--_Idem_, “Worms,” &c., _ibid._, p. 503, 1847.--_Idem_, “Report
on Helminthology, and on the Nemertinæ” (trans. by W. B. Macdonald, in
‘Ray Soc. Rep. on Zool.,’ 1842, p. 280), Edinburgh, 1845.--_Idem_ (see
Thomson).--_Thomson, A._ (for review of the writings of Meissner, Von
Siebold, and others, respecting the development of Mermis, Gordius,
&c., see the classical and elaborate art. “Ovum”), in ‘Supp. to Todd’s
Cyclop.,’ 1859.--_Vogt, C._, “On some Inhabitants (Cercariæ) of the
Fresh-water Mussels,” from ‘Ann. des Sci. Nat.,’ in ‘Ann. Nat. Hist.,’
1850.--_Whitman, C. O._, “The Embryology of Clepsine (with valuable
Bibliography),” ‘Quart. Journ. Micr. Sci.,’ July, 1878.
APPENDIX.--The memoirs announced by Dr T. R. Lewis in the January
issue of the ‘Microscopical Journal,’ and referred to at the close
of my account of _Filaria Bancrofti_, having appeared, I fulfil the
promise previously made (p. 202). In the few lines at my disposal I
may observe that the beautiful brochure (quoted below) supplies fuller
details of the results already announced by Lewis in the ‘Proceedings
of the Asiatic Society of Bengal.’ In respect of the nematoid
hæmatozoa, the memoir is chiefly important as confirming Manson’s
observations regarding the changes undergone by the Filariæ that have
been transferred to the stomach of the mosquito, and especially also,
as advancing some novel facts in reference to the occurrence of bird’s
blood-corpuscles, associated with embryonic nematoids, in the same
viscus of the insect. The worms are regarded by Lewis as transferred
avian hæmatozoa, a view which gains strength by their comparison with
the similar larvæ which he had detected in the blood of Indian crows
(_Corvus splendens_). In Egypt, as Sonsino had himself informed me by
letter, similar hæmatozoa are to be found in crows, and avian filariæ
of this kind were long previously described, as Lewis and Sonsino point
out, by Borell, Herbert, Schmidt, and Virchow. Facts of this order
undoubtedly complicate matters, and suggest that extreme measure of
caution in drawing conclusions, which Lewis himself everywhere displays.
Respecting the final changes undergone by the mosquito-filariæ before
their re-entrance into the human body, Lewis does not appear to have
gone further than Dr Manson. By rupturing the body of the most advanced
larvæ, Lewis readily recognised the œsophagus and intestine, but he
remarks, significantly, “I have not been able to distinguish any other
differentiated viscus in any of the specimens, and certainly, nothing
suggestive of differentiation of sex” (p. 83). In an earlier part of the
memoir Dr Lewis takes objection to my view that the urinary nematoids
found by me in a case of Bilharzia are genetically related to _Filaria
sanguinis hominis_. His distinguished coadjutor, Dr D. Cunningham,
also denies the possibility of such relationship. No doubt, if the
urinary maternal worm was really oviparous my view is untenable; but the
proved presence of imperfectly formed ovarian ova, in which no trace of
embryonic formation was discernible, has forced upon me the conviction
that prolapsus and rupture of the uterine tubes of the parent worm had
occurred, and that their rupture had occasioned the escape of ova in
various stages of growth. As free embryos were also detected, the adult
worm was probably viviparous. There is an error in the representation
of the oval-shaped ovum given in the figure (p. 183). I retain drawings
of eighteen perfect nematoid ova from the Bilharzia case, and not one
of these shows any double contour of the chorional envelope. In the
case of the imperfect ova, the double contour is obviously due to the
close apposition of the yelk-membrane to the shell-membrane, there being
no true shell. As regards “a correction” which Lewis makes in respect
of the question of priority of description of the mature _Filaria
sanguinis hominis_ I can only find space to state frankly, that Lewis
is perfectly correct. The error was quite unintentional on my part. The
adult worm was first discovered by Bancroft, and upon the strength of
his admittedly scanty record I named the worm _Filaria Bancrofti_. In
the matter of supplying a proper diagnosis and an anatomical description
I was completely anticipated by Lewis. No doubt, Dr Bancroft could have
furnished a fuller description of the parasite, had he desired to do so,
but here is what he says in the letter addressed to me from Melbourne on
the 20th of April, 1877:--“I thought it better to send you this account
of filariæ than to publish it _direct_, as you so kindly set me on the
track of the investigation.” Here I feel constrained to remark that
few, if any, of my many correspondents in helminthology, have displayed
more engaging candour. Whilst actually writing this Appendix (April
15th, 1879) I have received a new record of filarious cases from Dr
Bancroft, who also sends me some mosquitoes captured by a victimised
patient whose blood swarmed with filariæ. In one of the captured
insects Bancroft himself detected forty-five filariæ. The cases have
been forwarded to the ‘Lancet’ for publication. Lastly, in reference
to the closing paragraph of Bancroft’s previous letter to me (pub. in
the ‘Lancet,’ Feb. 1st), I have received the following interesting
commentary at the hands of Dr Silva Araujo, whose letter is dated from
Bahia, March 3rd, 1879:--“Je dois vous communiquer que ce fait vient
confirmer l’idée qui existe chez nous, où le peuple croit et affirme
que--quand une personne qui souffrait auparavant d’erysipèle a un abcès
cela la préserve de nouveaux accès. La raison ne sera-t-elle pas que
dans ce cas, avec l’ouverture de l’abcès, le ver sort? Je le crois.
Ces faits viennent démontrer que la cause de la maladie est le ver.
Cependant nous avons ici à Bahia plusieurs confrères qui ne le croient
point! Et à Rio-de-Janeiro aussi il y en a, peut-être davantage (!).” I
will only add that Dr Araujo deceives himself if he imagines that the
full etiological significance of parasites in relation to disease will
receive general professional recognition for many years to come.
SUPPLEMENT TO BIBLIOGRAPHY No. 23, p. 202 (with emendations).--_Araujo_,
‘Memoria sobre a Filariose ou a molestia produsida por uma nova especie
de parasita cutaneo,’ Bahia, 1875.--_Idem_, “Da filariose,” ‘Globo,’
Jornal do Rio de Janeiro, 1876, e ‘Revista Medica do Rio de Janeiro,’
1876, anno 3o, No. 2, 15 de Julho, p. 107.--_Idem_, “Caso de chyluria,
elephancia do escrôto, escrôto lymphatico, craw-craw e erysipela em
um mesmo individuo; descobrimento da Wuchereria filaria na lympha do
escrôto. Tratamento pela electricidade com excellentes resultados,”
‘Gaz. Med. da Bahia,’ 2a serie, vol. 2o, No. 11, Nov. de 1876.--_Idem_,
“A _Filaria Wuchereri_ no sangue,” ‘Gaz. Med. da Bahia,’ Mar. de 1878,
p. 106, e seguintes.--_Idem_, “A muriçoca e as filarias Wuchereri,”
‘Gaz. Med. da Bahia,’ Setembro de 1878.--_Idem_, “La _Fil. immitis_,”
&c., Transl. of Mem. (_l. c._, Bibl., No. 45) in ‘Lyon Médical,’ Nov.,
1878, p. 319 et 363.--_Bancroft_, “Instance of a European having taken
leprosy in Queensland,” in a letter to myself; see “Case from Bancroft,”
quoted at p. 203.--_Chassaniol, A._ (et _F. Guyot_), “Hématurie
graisseuse ou chyleuse,” in their “Notes de Géographie Méd. recueillies
à Taïti,” in ‘Archives de Méd. Navale,’ Jan., 1878, p. 65.--_Cobbold_,
“Worms in the Heart of Dogs,” letter in the ‘Lancet,’ April 5, 1879,
p. 498.--_Coles_, “On Lymph-scrotum,” ‘Brit. Med. Journ.,’ March 9,
1878.--_Fayrer, Sir J._, “Lecture on Elephantiasis Arabum,” in the
‘Lancet,’ March 29, 1879, p. 433.--_Idem_, ‘Report of Pathol. Soc.,’
‘Lancet,’ Feb. 22, 1879, p. 267.--_Idem_, ‘Rep. of Epidemiological
Soc.,’ _ibid._, p. 269.--_Idem_, ‘Letter on Filaria;’ see
_Hoysted_.--_Ghaleb, O._ (with P. Pouquier), “On _Filaria hæmatica_,”
from ‘Comptes Rendus,’ Feb. 5, 1877, in ‘Annals Nat. Hist.,’ April,
1877.--_Hoysted, J._, “Notes of a Case of _Filaria sanguinis_ in a Dog;”
see Bibliog. No. 49, p. 311.--_Lewis, T. R._, ‘The Microscopic Organisms
found in the Blood of Man and Animals, and their relation to Disease,’
Calcutta, 1879.--_Idem_, “The Hæmatozoa of Man (excerpt of the above),”
‘Quart. Journ. of Microsc. Sci.,’ April, p. 245 (both from ‘14th Ann.
Rep. of the San. Commissioner with the Govt. of India’).--_Makuna_,
‘Letter respecting _Fil. sang. hom._ in Chyluria’ (l. c., Bibliog. No.
23).
INDEX.
_Acanthia lectularia_, or the common bed bug, 273
_Acanthocephala_ in birds, 446
" include but one family, 5
" in the Hunterian Museum, 413
_Acanthotæniadæ_, a family of tapeworms, 4
_Acaridæ_, a family of Arachnida, 5
Acephalocysts in cattle, Hunterian specimens of, 140
Agricultural societies, their indifference to helminthology, 412
Aguti, _Spiroptera mediospiralis_ from the, 403
Alligator, entozoa from an, 455
_Amphistoma_ and _Polystoma_ in the frog, 452
" _hominis_, notice of Lewis’s and McConnell’s, 36
" _subclavatum_, ciliated embryo of, 49
Amphistomes infesting deer, 332
" " elephants, 395
" " the horse, 357
_Amphistomidæ_, a family of flukes, 4
Anæmia, tropical, due to Anchylostomata, 203
Anchylostomum-helminthiasis, Wucherer’s account of the, 213
_Anchylostomum_ (_Dochmius_) _duodenale_, description of, 212
Aneurism of the horse, Bollinger’s account of, 368
_Anguillula_ (_Leptodera_) _stercoralis_, description of, 234
_Anguillulidæ_, a family of round worms, 5
Annelid parasites, ectoparasitic character of the, 5
_Anoplocephala perfoliata_ as a synonym, 401
Ant-eaters, internal parasites of, 321
Antelopes and deer, Pentastomes found in, 350
_Anthomyia canalicularis_ as a human parasite, 271
Arachnid parasites, various families of, 5
_Argulidæ_, a family of parasitic crustaceans, 6
_Arhynchotænia critica_ of the hyrax, 403
_Arhynchotæniadæ_, considered as a group, 4
Armadillo, parasites found in the, 321
_Ascaridæ_, a family of round worms, 4
Ascarides infesting cetaceans, 426
" (Oxyurides) in relation to cleanliness, 232
_Ascaris alata_, Bellingham’s so-called, 237
" _Cornelyi_ from the vulturine pintado, 447
" _halicoris_ from the Indian dugong, 429
_Ascaris infecta_ from _Passalus cornutus_, 483
" _lumbricoides_ as a human parasite, 243
" " Davaine’s experiments with, 244
" " development of the, 244
" " Heller’s “find” respecting the young of, 244
" " remarkable cases caused by the, 248
" _maculosa_ causing avian epizoöty, 441
" " Unterberger’s experiments with, 245
" _megalocephala_ and _A. lumbricoides_ not identical, 243
" " experiments with the eggs of, 246
" " of solipeds, 378
" _mystax_ considered as a human parasite, 237
" " Leuckart’s experiments with, 244
" " researches of Nelson respecting, 240
" _nigrovenosa_, parthogenesis of, 452
" _suilla_ considered as a synonym, 243
" " of the hog, a synonym, 405
" _tentaculata_ of opossums, 433
" _tetraptera_, development of the embryos of, 245
" _vesicularis_ from the ring-necked pheasant, 442
_Aspidocephalus scoleciformis_ of opossums, 433
_Aspidocotylus mutabilis_, a parasite of fish, 360
Ass, frequency of aneurism in the, 367
" liver-fluke frequent in the, 356
" strongyles from the stomach of the, 383
Australian entozoa, Mr Krefft’s _brochure_ on, 431
" hedgehog, tapeworm from the, 433
Avian hæmatozoa, observations by Lewis on, 486
" parasites in the British Museum, 448
" " in the Hunterian Museum, 448
_Bacteria_, the best known forms of, 277
_Bacteridæ_, as a family of protozoa, 7
_Balantidium_ (_Paramecium_) _coli_ of man, 282
" semiparasitic character of, 7
_Balæna_, flukes occurring in the genus, 421
" _rostrata_ infested by _Ascaris angulivalvis_, 426
_Balænoptera rostrata_, filariæ from, 425
" " fluke from, 421
Bats, entozoa and ectozoa infesting, 294
Bear, Cysticerci in the heart of a, 140
Beef, cyst-infected, quantity destroyed in India, 76
" in India, prevalence of “measled”, 61
" tapeworm, description of the so-called, 56
Bee, parasite of the, known to John Hunter, 480
Beetles (_Passalus_) infested by nematodes, 483
_Beluga leucas_, worm from the ear of, 427
_Bilharzia hæmatobia_, history and development of the, 38
Birds, frequency of entozoa in, 434
" _Spiroptera helicina_ in the feet of, 440
" the gape disease in, 443
Blackbirds, tapeworms destructive to young, 440
Blackcap, flukes reared by Zeller in the, 436
Blackfish or tursio, cestode from the, 422
Bladderworms and measles in cattle, 62
_Blaptidæ_ as parasitic insects, 7
_Blaps mortisaga_ as a human parasite, 270
Bleak, the (_Leuciscus_), a possible source of tapeworm, 301
" the, in relation to _Bothriocephalus latus_, 470
Bonito, parasites from the, 458
_Bopyridæ_, a family of parasitic crustaceans, 6
_Bothriocephali_ of water-birds obtained from fish, 468
" researches of Bertolus and Duchamp on, 110
_Bothriocephalus cordatus_, brief description of, 111
" _cristatus_, brief description of, 111
" in Holland, Dr. Fock’s remarks on, 109
" _latus_, distribution and characters of, 106
" " source and proscolices of, 107
" _proboscideus_ of the salmon, 468
" _tropicus_, note on the so-called, 96
Bot infesting the stomach of the rhinoceros, 401
Bottle-head (_Hyperoödon_), flukes from the, 421
Brain, Cysticerci occurring in the human, 92
Bronchi of whales, worms in the, 425
_Bucephalus_ probably a larval state of Gasterostoma, 462
" regarded as a germ-sac, 453
Bug, the common, as a human parasite, 273
Cachalot, cestode from the high-finned, 422
_Calceostoma_, hooks of the suckers of, 464
_Caligidæ_, a family of crustaceans, 6
_Campula oblonga_ regarded as a synonym, 419
Capercaillie, entozoa of the, 440
" _Trichosoma_ and _Ligula_ from a, 447
_Carnivora_, internal parasites of the, 297
_Cataphractus_ infested by _Aspidocotylus_, 360
Cat, Australian, _Bothriocephalus_ from, 309
" flukes and tapeworms infesting the, 308
Cattle diseased by parasites, natural cure of, 83
" measles and bladderworms in, 61
" of the Upper Punjab infested by cysts, percentage of, 75
" plague bodies, nature of the so-called, 280
" species of lice infesting, 352
" tapeworms found in, 332
_Cercaria diplocotylea_ of water-snails, 452
" of the common fluke, 325
_Cercariæ_ and _Rediæ_, Pagenstecher’s remarks on, 452
_Cercomonas hominis_ in cholera dejections, 282
_Cestoda_, families of the order, 4
Cestode (larval) in _Delphinus delphis_, 422
_Cetacea_, external parasites of, 428
" parasites of, 416
" " in Hunterian collection, 427
" worms in the lungs of, 423
" " in the cranial sinuses of, 425
Chacma, strongyles found in the, 291
Charbon, an anthracoid disease associated with bacterids, 278
Cheetah, tapeworm found in the, 300
_Cheiracanthidæ_, a family of round worms, 4
_Cheiracanthus robustus_ in Indian dogs, 305
" " mistaken for _Echinorhynchus_, 257
_Cheiroptera_ or bats, parasites of, 293
Chigoe or jigger as a human parasite, 274
Chinese missionary, flukes in the family of a, 21
Cirrhipeds, parasitic, upon whales, 428
Civets, parasites found in, 299
Classification of Schneider referred to, 4
_Clepsinidæ_, a family of suctorial annelids, 5
Coati, intestinal worms of the, 298
Cochin-China diarrhœa due to _Leptodera_, 235
Cockchafers harbor young Echinorhynchi, 413
Cockroaches (_Blatta_) infested by nematodes, 483
Codfish, frequency of filariæ in the, 472
_Cœnuri_ from rabbits in Guy’s Museum and at Oxford, 140
" researches of Rose and Numan respecting, 334
_Cœnurus cuniculi_, specimen of, from Ayrshire, 140
" _serialis_ of the hyrax, 408
_Conocephalus typicus_ from a dolphin, 426
_Conopidæ_, the larvæ of, as parasitic insects, 6
_Conorhinus nigrovarious_ or pampas benchucha, 273
_Cotylogaster cochleariforme_ not an equine parasite, 360
Crane, entozoa from a, 447
_Crossophorus collaris_ of the hyrax, 403
Crocodile, worm from beneath the skin of a, 456
Crows, hæmatozoa in Indian, 486
_Crustacea_, parasitic, upon whales, 428
" the, as alleged human parasites, 269
Crustacean parasites, families of, 6
Crustaceans, entozoa infesting, 480
_Cucullanidæ_, a family of round worms, 4
" development of the, 474
_Culex_, various species of, attacking man, 273
Curlew, entozoa from the, 447
_Cuterebra noxialis_, or Macaco worm, 271
Cuttle-fishes, tapeworm larvæ found in, 468
_Cyamidæ_ included with Pycnogonidæ, 5
_Cyamus balænarum_ or whale-louse, 428
_Cyclobdella lumbricoides_, the, of Brazil, 259
_Cyclops_ considered as an intermediate host, 223
_Cymothoidæ_, a family of parasitic crustaceans, 6
“Cyst”-affected meat in the Punjab, quantity of, 76
Cystic disease in cattle, Dr J. Fleming on, 76
" entozoa are larval tapeworms, 4
Cysticerci, common situation of, in ration meat, 78
" destruction of, by calcareous degeneration, 83
" detected in the living animal, 78
" from sheep, Dr Maddox on, 98
" from the nasal sinuses of a porpoise, 421
" from the skin of _Physeter_, 421
" in the heart of a bear, 140
" in the human body, seat of, 91
" in the psoas muscles, Dr Joseph Fleming on, 75
" in meat, Pellizzari’s and Tommasi’s researches on, 62
" investigations of Lewis respecting, 66
" monstrous varieties of, 105
" of the sheep alleged to contain eggs, 98
" prophylactic measures respecting, 83
" researches by Perroncito on, 67
" said to be capable of swimming, 97
" temperature necessary to destroy, 69
" voluntarily swallowed by Italian gentlemen, 71
_Cysticercus bovis_ found in the liver and lungs, 59
" " human feeding experiments by Oliver with, 72
" _delphini_, nature of the so-called, 422
" found in the dog, 302
" from the Red River hog, 405
" in the brain, cases of, 92
" of the sheep, discovery of the, 97
" report by Dr Neill respecting, 80
" (_telæ_) _cellulosæ_, or pork measle, 89
" _tenuicollis_ found in man, 101
" " , the self-feeding experiment by Möller with, 72
Cysts at the root of the tongue, diagnostic value of, 80
" of the liver containing psorospermiæ, 282
_Dactylogyrus_, allusion to the eggs of, 42
Dasse (_Hyrax_), parasites of the, 403
_Dasyprocta aguti_, stomach excrescences in, 403
Deaths from worms, Registrar General’s returns of, 285
Deer, abundance of amphistomes in, 332
" filariæ found in various kinds of, 350
_Delphinus Forsteri_, tapeworm found in, 422
" _phocæna_, cestode (_Diphyllobothrium_) from, 422
" _rostratus_, tapeworm from, 422
" _tacuschi_, flukes found by Natterer in, 417
_Demodex folliculorum_ of man and dog, 266
_Dermatophagoides Schérémétewsky_, the so-called, 266
_Dibothridæ_ and _Bothriocephalidæ_ as synonyms, 4
_Dibothrium hians_, supposed monstrous state of, 105
_Dichelestidæ_, a family of crustacean parasites, 6
_Dicotyles_ (Peccary), parasites of the genus, 404
_Dicrocœlium Buskii_ as a synonym, 20
_Didelphys philander_, acanthocephalous worm of, 434
_Diphyllobothridæ_, a family of tapeworms, 4
_Diphyllobothrium stemmacephalum_ from a porpoise, 422
_Diplodiscus subclavatus_, water-vessels of the larvæ of, 51
_Diplozoon_ in the _Diporpa_ condition, 464
Diseased meat from “rot”, 331
_Distoma Andersoni_ from _Platanista_, 420
" _campula_ of the porpoise, 418
" _clavatum_, particulars respecting, 458
" _conjunctum_ as a human parasite, 30
" _crassum_ or Busk’s fluke, 20
" _cygnoides_, ciliated embryo of, 49
" _gigas_ of Nardo, description of the, 460
" _hepaticum_ a synonym of Fasciola, 15
" _heterophyes_, description of the, 34
" _lancea_ infesting dolphins, 416
" _lanceolatum_ as a human parasite, 17
" " ciliated embryo of, 49
" " description of the, 18
" _leptosomum_ and _D. brachysomum_, source of, 438
" _macrostomum_, development of, 435
" _megastoma_, ciliated embryo of, 49
" _militare_, development of, 436
" _neuronaii Munroii_, the so-called, 52
" _ophthalmobium_, notice of the so-called, 36
" _sinense_, or the Chinese fluke, 29
" species of, in _Delphinus Forsteri_, 421
_Distomata_ confounded with proglottides, 16
_Distomidæ_, a family of flukes, 4
_Distomum spatulatum_ as a synonym, 28
_Dochmius duodenalis_, discovery of, by Dubini, 211
" _Sangeri_ from the elephant, 399
Dogs, destruction of dogs by heart-worms, 304
Dog, ectozoa and follicle mites of the, 307
" internal parasites of the, 300
Dolphin, remarkable worm from the stomach of a, 426
Dolphins, fluke parasites of, 416
Dorado, _Fasciola fusca_ from the, 459
_Dracunculus_, description of the embryos of, 221
" Fedschenko’s discovery respecting, 223
" _medinensis_, description of the, 217
Duck, worms from a dusky, 447
Dugong, parasites of the, 429
Ear of the porpoise, worms found in the, 427
Earth-wolf, remarkable parasite from the, 299
Earth-worms as intermediate bearers, 346
Earwig, _Filariæ_ found in the, 483
Echidna, tapeworm from the, 433
Echinococci described by Leuckart and Naunyn, 117
Echinococcus brood-capsules known to Wilson and Busk, 117
_Echinococcus hominis_, synonyms of, 112
" _multilocularis_ found in a calf, 116
_Echinorhynchidæ_ abound in fishes and reptiles, 5
Echinorhynchi found by John Hunter, 427
" infesting monkeys, 292
" in trout, frequency of, 475
" of water newts, 455
_Echinorhynchus angustatus_ and _E. hominis_, 413
" _gigas_ as a human parasite, 256
" " of the hog, 412
" _hominis_, Lambl’s so-called, 256
" in man, Welch’s supposed case of, 256
" Leuckart on the development of, 476
" _microcephalus_ from an opossum, 434
" _Muriei_ from a whale, 427
" _pellucidus_ and _E. brevicollis_, 428
" _porrigens_ from whales, 427
" _spirula_ of monkeys, 413
" _transversus_ in birds, 446
_Echinostoma hispidum_ from a sturgeon, 462
Ectozoa of swine, 414
" of the elephant, 399
" of whales, 428
Edentata, parasites of the, 321
Eel, _Echinorhynchi_ in the, 475
Eggs, entozoa found in the interior of, 440
Elephants destroyed by “rot” in Burmah, 394
" earth-eating habits of worm-infected, 395
" ectozoa of, 399
" in England destroyed by worms, 399
" parasites infesting, 393
" parasitic diseases of, 397
_Entozoa_ do not result from diseased states, 1
" of game birds, list of, 440
" their relation to the helminths, 8
Epidemics of rot disease, 327
_Epizoa_, haustellated crustacean parasites, 6
Epizoöty amongst elephants from flukes, 394
" amongst pigeons, 441
" in birds, very destructive to life, 435
" in cats, Dr Romano’s account of, 308
" in swine from _Echinorhynchus_, 413
" in tenches from _Ligulæ_, 469
" in the hog from _Stephanurus_, 411
" in the Mauritius from worms, 382
" in the pig from _Strongyli_, 412
" in young blackbirds from tapeworms, 440
_Eustrongyli_ within the skull of water-turkeys, 446
_Eustrongylus gigas_, description of, 207
" " in dogs and wolves, 305
" " source of the, 208
" " wild animals infested by, 207
" _papillosus_ from a crane, 447
Eye-worms in cattle, 349
Eye of the fowl infested by filariæ, 440
_Fasciola clavata_, description of the so-called, 459
" _hepatica_ as a human parasite, 14
" " as a “zoological” individual, 325
" " ciliated embryo of, 48
" _Jacksoni_ infesting elephants, 397
_Fauna_, parasites form a peculiar, 2
Ferret, ectozoon infesting the ears of the, 307
_Filaria acuta_ in the limbs of birds, 447
" _Bancrofti_, history of the discovery of, 180
" _gracilis_ infesting monkeys, 291
" _hominis oris_, description of the, 206
" _horrida_ from the American ostrich, 447
" _immitis_ in the heart of dogs, 304
" _inflexicaudata_ from _Balænoptera_, 425
" " of the porpoise, 425
" _labialis_, description of the, 206
" _lacrymalis_ as a synonym, 206
" _lentis_, notice of the so-called, 205
" _loa_, notice of the so-called, 205
" _macropodis gigantei_ in the Hunterian Museum, 433
" _Mansoni_ in the eye of a fowl, 441
" _medinensis_ considered as a synonym, 217
" _microstoma_ and _F. megastoma_,
temperature necessary to kill, 70
" _oculi_ considered as a synonym, 383
" _papillosa hæmatica canis domestici_, 184
" " in the horse, 383
" _Salisburyii_ considered as a synonym, 187
" _sanguinis_, Bancroft’s account of the, 189
" " _equi_, the so-called, 384
" " _hominis_, correction respecting, 487
" " " discovery by Lewis of, 183
" _spelæa_ from a wallaby, 433
" (_Strongylus_) _bronchialis_, description of, 207
" _terebra_ in the black-tailed deer, 349
" _trachealis_, remarks on the, 207
" _Websteri_ proposed as a synonym, 433
_Filariæ_ as a cause of abscess and erysipelas, 487
" discovery of microscopic, by Wucherer, 183
" hæmatozoal, of Grube and Delafond, 303
" in human blood, Sonsino’s verification of, 185
" of the mosquito, Manson’s description of, 194
_Filaridæ_, a family of round worms, 5
Fishes largely infested by _Echinorhynchi_, 477
" of Brazil, amphistomes in the, 463
" parasites of, 457
Flea, the common, of man, 274
Fluke, description of the common liver, 15
" description of the large human, 24
" origin and meaning of the term, 4
Flukes abundant in the great kangaroo, 431
" causing “rot” in elephants, 394
" found in fishes, 457
" found in ruminating animals, 323
" Pagenstecher’s researches on, 452
" their destiny favored by mimetism, 436
Fox, fluke of the American red, 299
" source of tapeworms infesting the, 300
Fowl, entozoa infesting the common, 440
Free nematoids, Villot’s opinion respecting the, 483
Frog, _Ascaris nigrovenosa_ of the, 452
_Galeodes araneoides_ or canal tick, 267
_Gallinula chloropus_, worms in the limbs of, 447
_Gamasidæ_, a family of Arachnida, 5
Game birds, list of entozoa infesting, 440
_Gammarus pulex_ as an intermediate host, 476
Gape disease, methods of preventing and treating the, 445
“Gapes” in birds due to _Sclerostoma_, 443