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THE INTERNATIONAL SCIENTIFIC SERIES.
VOLUME XIX,
Il.
OU
EV:
VI.
VII.
WELT:
1X.
XI.
XII.
XIII:
XIV.
XV.
XVI.
DEVEL.
XVIII.
XIX.
THE INTERNATIONAL SCIENTIFIC SERIES.
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QL
157
R Ub ( THE INTERNATIONAL SCIENTIFIC SERIES.
1a er
aes
Inv ert. L0 d\.
ANIMAL PARASITES AND MESSMATES.
BY
P. J. VAN BENEDEN,
PROFESSOR AT THE UNIVERSITY OF LOUVAIN, COKRESPONDENT OF THE INSTITUTE OF
FRANCE.
WITH EIGHTY-THREE ILLUSTRATIONS.
NEW YORK:
eee ee LON. AND COMPANY,
549 & 551 BROADWAY.
1876.
CONT Pher Ss.
INTRODUCTION.
Adaptation of Food to Animals—Animal Manutiotitee = Petcdudesa"
Messmates—Mutualists—Theory of Spontaneous Generation ... Xiii
CHAPTER I.
ANIMAL MESSMATES.
Definition—Free Messmates—Fixed Messmates oa oon oo =o
CHAPTER II.
FREE MESSMATES.
Found in all Classes—Fierasfers in Holothuride—Pilot Fish—
Remora—Crustacean Messmates—Poisoning by Mussels—Pearl
Mussel and small Crab—Dromize—Turtle Crabs—Macrourous
Decapods—Hermit Crabs—Friendship of Pagurus and Anemone
—Isopods — Messmates on Whales — Molluscan Messmates—
Lerneans — Distomes—Messmates of the Echinodermata—Of
Sponges—Infusorial Messmates... eee soe ove vee
CHAPTER III.
IXED MESSMATES.
Cirrhipedes—Importatice of Embryology—Recurrent Development
—Messmates, characteristic of the various Species of Whales
—Cirrhipedes on Sharks — Crustaceans, Messmates on other
Crustaceans — Cirrhipedes on Molluscs — Bryozoa — Fossil
Messmates—Messmates on Sponges—Spicules of Hyalonema—
Ophiodendrum ae cee oe — eee
53
Vili CONTENTS.
CHAPTER IV.
MUTUALISTS.
Definition — Ricinidee— Trichodectes of Dog harbouring Larva of
Teenia—Areguli—Caliguli—A ncei— Pranize— Cyami—Nematode
Mutualists—Strange form of Histriobdelle—Kgyptian Distome
in Man “54 500 a
CHAPTER V.
PARASITES.
Distinction between Parasites and Carnivora—Parasites found on all
Classes of Animals—Males dependent on Females—Parasites on
Man—Abundant Parasites in Stork—All the Organs nourish
Parasites — Different size of Male and Female —Lerneans—
Diplozoa—Migration of Parasites—Corresponding Changes of
Form—Parasites restricted to certain Regions—Former Theory
of Spontaneous Generation ... eae ves eee eee
CHAPTER VI.
ae PARASITES FREE DURING THEIR WHOLE LIFE.
Leeches —Vampires—Cylieobdell:«—Branchellions —Gnats— Black-
flies—Mosquitoes—Gnats in high Latitudes—Tsetse—Ox-flies—
Pteropti—Nycteribie—Bugs—Lice—Fleas—ltch Insect—Acari
on Beetles and Bees—Cheyletus eruditus ese soe
CHAPTER VII.
PARASITES FREE WHILE YOUNG.
Isopod Parasites —Chigoe — Ticks— Pigeon-mite — Bopyridse — Ich-
thoxenus — Peltogasters —Tracheliastes—Penellee—Lerneans—
Guinea-worm — Leptodera of Snail— Nematodes in Bones—
Lichnophorse—Gregarinz
CHAPTER VIII.
PARASITES THAT ARE FREE WHEN OLD.
Utility of Ichneumons—Scolix of Tan-beetles—Scolyti of Seychelles
Cocoa-nut Trees— Elms at Brussels destroyed by Scolyti
PAGE
68
85
LOF
. 1838
CONTENTS. 1x
—Polynema in Eggs of Dragon-fly —Sphex — Platygaster —
Horse-fly —Livingstone—Animals in Paraguay destroyed by
Hippobosci—Dipterous Parasites on Sheep and Stag—Gordius—
Shower of Worms—Eels in Ears of Corn dan sas eee 162
CHAPTER IX.
PARASITES THAT MIGRATE AND UNDERGO
METAMORPHOSES.
Nostosites—Xenosites—Hosts serving as a Créche, a Vehicle, or a
Lying-in Hospital—Lamarck on Spontaneous Generation—Tre-
matodes—Monostomes—Sporocysts and Cercarize—Passage from
one Host to another — Distomes — Flukes — Hemistomes —
Amphistomes—Teeniz of the Dog and Wolf—Hydatids—Teenia
solium in Man—Cysticercus of Pig—Cysticercus of Rabbit and
Hare passing into Dog—Ccenurus of Sheep—Bothrio¢ephalus—
Linguatula in Negro—Strongyli—Trichine—Panic in Germany
—Vibriones in Corn—Kchinorrhynchus—Dicyema ap as AGG
CHAPTER X.
PARASITES DURING THEIR WHOLE LIFE.
Strepsitera—Stylops—Rhipiptera—Tristomidx— Epibdella — Diplo-
zoon, two Individuals—Polystomum of Frog—Gyrodactyles—
Cochineal Insect—Aphides—Phylloxera of Vine—An Acaris,
its Mortal Enemy—Ant-Cows— Bonnet’s Theory of Germs—
The Reduvius personatus, a valuable enemy to the Bed-bug ... 255
LIST OF ILLUSTRATIONS.
FIG.
1.—Ophiodendrum abietinum on Sertularia abietina ee
2.—Ricinus of the Pygarg
3.—Caligulus elegans, female: ditto, Pata ale size ...
4.—Different forms of the Bite of a Leech ...
5.—Sucker and jaws”... nee eee vee eee vee
6.—Anatomy of Leech ... 530 Sh en
7.—Antenna of Gnat
8.—Gnat, male and female
9, 10.—Lucilia hominivora
il; ieee és oe
12.—Antenna of ox HY: Ge
13.—Blue-fly
14.—Flesh-fly ae
15.—House-fly
16.—Bed-bug eat
17.— Louse ue si
18.—Louse—Suckers ws “sa a fale ean ate
19.—Ditto—Claw e's Sc sce Res sc3
20.—Flea (Pulex aii er ae ave eae 5
21.—Itch-mite te “ss
22.—Ditto, Pt ake view . a aes nee
23.—Ditto, male—back view
24.—Geographical water-mite
25.—Book-mite
26.—Chigoe, male So ais 40 mae ane ae
27.—Ditto, head ae oe aa
28.—Ditto, female mee son oes a A
29.—Phryxus Rathkei ... pee one ane :
PAGE
66
72
73
110
110
110
115
118
120
121
121
121
122
122
124
125
126
126
128
131
132
136
137
141
141
141
145
LIST OF ILLUSTRATIONS.
FIG.
30.—Tracheliastes of Cyprinids ied ove ee avs
31.—Lernea branchialis attached to Morrhua luscus
32.—Young Guinea-worm, showing Mouth, Tail, and section of Body
33.—Gregarinze of Nemertes f
34.—Sac with Psorospermiz from Sepia ofininnis st oe
35.—Stylorhynchus oligacanthus from Dragon-fly
36.—Horse-fly, showing also Anterior and Posterior Extremity
37.—Macaco Worm Lee es
38.—Melophagus of the Bhesp: ae ar
39.—Lipoptena of Stag Le vee
40.—Gordius aquaticus bate
41.—Monostomum ai aaah a acne with Gerona ses
42.—Liver fluke Ree
43.—Monostomum mutabile ..,. ate Bot ote
44,—Ditto, ciliated Embryo and young Cercariz
45.—Cercaria of Amphistoma sub-clavatum .., i ens
46.—Sporocyst of Amphistoma sub-clavatum .., vee he ee
47.—Ditto, from Frog... = eae ose Toe ee vee
48.—Polystomum integerrimum vee eu
49.—Cysticercus ae cee vee eee °
50.— Vesicular Worm ... fo
51.—Tape-worm (Tznia solium), showene Bealex cat Pr opiates
52.—Ditto, Rostellum and Suckers
53.—Tenia medio-canellata
54.—Coenurus of Sheep, and Hydatid .. _ See
55.—Scolex of Tzenia echinococcus ... was eee
56.—Tenia echinococcus from the Pig sea eee
57.—Ditto, from the Dog ae eos sa cee ah sue
58.—Bothriocephalus latus ee aa es ise eee
59.—Scolex of ditto ae ane nae coe
60.—Egg of ditto ae cee wag a:
61.—Tenia variabilis from Snipe a ase ae vee
62.—Ditto, more highly magnified ae ses
63.—Tetrarhynchus appendiculatus from the Plates.
64.—Hook of Linguatula ae ee
65.—Linguatula, showing Hooks Sad eee one ose ces
66.._Strongylus gigas, female ... ean - °
67.—Ascaris lumbricoides; also Head, Tail, and Boris cas eee
68.—Trichocephalus from Man : :
211
214
214
219
223
226
226
227
226
227
227
230
230
230
232
232
239
240
241
Xll LIST OF ILLUSTRATIONS.
FIG.
69.—Oxyuris vermicularis, natural size and magnified
70.—Trichina, free 300 ove
71.—Trichina encysted in Muselo es sic pee
72.—Echinorhynchus proteus... oes
73.—Sac with Psorospermiz from Sepia officinalis eee
74.—Gregarinz from Nemertes Gesseriensis
75.—Stylorhynchus oligacanthus Le Ea aa
76.—Dicyema Krohnii from Sepia officinalis ...
77.—Stylops sae a Sos
78.—Ditto, with embryos Shp spe
79.—Larva of Black Stylops
80.—Cochineal Insects, male... a aa
81 .— Ditto, female coo eoe eoe eee
82.—Aphis
83.—Rose Aphis, male AM female
PAGE
241
243
213
252
252
253
253
254
256
257
257
263
264
264
265
INTRODUCTION.
a ee
*‘ The edifice of the world is only sustained by the impulses of hunger
and love.” —ScHILLER.
In that great drama which we call Nature, each animal
plays its especial part, and He who has adjusted and
regulated everything in its due order and proportion,
watches with as much care over the preservation of the
most repulsive insect, as over the young brood of the
most brilliant bird. Hach, as it comes into the world,
thoroughly knows its part, and plays it the better
because it is more free to obey the dictates of its
instinct. There presides over this great drama of life
a law as harmonious as that which regulates the move-
ments of the heavenly bodies; and if death carries off
from the scene every hour myriads of living creatures,
each hour life causes new legions to rise up in order
to replace them. It is a whirlwind of being, a chain
without end.
This is now more, fully known; whatever the animal
may be, whether that which occupies the highest or the
lowest place in the scale of creation, it consumes water
and carbon, and albumen sustains its vital force.
XIV INTRODUCTION.
Therefore, the Hand which has brought the world
out of chaos, has varied the nature of this food; it has
proportioned this universal nourishment to the neces-
sities and the peculiar organization of the various species
which have to derive from it the power of motion and
the continuance of their lives.
The study whose aim is to make us acquainted with
the kind of food adapted to each animal constitutes an
interesting branch of Natural History. The bill of fare
of every animal is written beforehand in indelible cha-
racters on each specific type; and these characters are
less difficult for the naturalist to decipher than are
palimpsests for the archzologist.
Under the form of bones or scales, of feathers or
shells, they show themselves in the digestive organs. It
is by paying, not domiciliary, but stomachic visits, that
we must be initiated into the details of this domestic
economy. The bill of+fare of fossil animals, though
written in characters less distinct and complete, can
still be very frequently read in the substance of their
coprolites. We do not despair even to find some day
the fishes and the crustaceans which were chased by the
plesiosaurs and the ichthyosaurs, and to discover some
parasitic worms which had entered with them into the
convolutions of the intestines of the saurians.
Naturalists have not always studied with sufficient
care the correspondence which exists between the animal
and its food, although it supplies the student with infor-
mation of a very valuable kind. In fact, every organized
body, whether conferva or moss, insect or mammal,
becomes the prey of some animal; every organic sub-
stance, sap or blood, horn or feather, flesh or bone,
INTRODUCTION. XV
disappears under the teeth of some one or other of these;
and to each kind of débris correspond the instruments
suitable for its assimilation. These primary relations
between living beings and their alimentary regimen call
forth the activity of every species.
We find, on closer examination, more than one
analogy between the animal world and human society;
and without much careful scrutiny, we may say that
there is no social position which has not (if I may dare
to use the expression) its counterpart among the lower
animals.
The greater part of these live peaceably on the fruit
of their labour, and carry on a trade by which they gain
their livelihood ; but by the side of these honest workers
we find also some miserable wretches who cannot do
without the assistance of their neighbours, and who
establish themselves, some as parasites in their organs,
others as wninvited guests, by the side of the booty which
they have gained.
Some years ago, one of our learned and ingenious
colleagues at the University of Utrecht, Professor Hart-
ing, wrote a charming book on the industry of animals,
and demonstrated that almost every trade is known in
the animal kingdom. We find among them miners,
masons, carpenters, paper manufacturers, weavers, and
we may even say lace-makers, all of whom work first
for themselves, and afterwards for their progeny. Some
dig the earth, construct and support vaults, clear away
useless earth, and consolidate their works, like miners;
others build huts or palaces according to all the rules of
architecture ; others know intuitively all the secrets of
the manufacturers of paper, cardboard, woollen stuffs or
XVi INTRODUCTION.
lace; and their productions need not fear comparison
with the point-lace of Mechlin or of Brussels. Who has
not admired the ingenious construction of the beehive
or of the ant-hill, or the delicate and marvellous struc-
’ ture of the spider’s web? The perfection of some of
these works is so great and so generally appreciated, —
that when the astronomer requires for his telescope a
slender and delicate thread, he applies to a living shop,
to a simple spider. When the naturalist wishes to test
the comparative excellence of his microscope, or requires
a micrometer for infinitely little objects, he consults, not
a millimetre, divided and subdivided into a hundred or
a thousand parts, but the simple carapace of a diatom,
so small and indistinct that it 1s necessary to place.a
hundred of them side by side to render them visible to
the naked eye: and still more, the best microscopes do
not always reveal all the delicacy of the designs which
decorate these Lilliputian frustules. Mons. H. Ph. Adan
has lately shown, with an artist’s talent, the infinite
beauties which the microscope reveals in this invisible
world.
To whom do the manufacturers of Verviers or of
Lyons, of Ghent or of Manchester, apply for their raw
materials? Hither to an animal or a plant; and even
up to the present time we have had sufficient modesty
not to have sought to imitate either wool or cotton. Yet
these animal manufacturers carry on their operations
every day under our eyes, the doors wide open to every-
body, and none of them is as yet marked with the trite
expression, ‘‘ No admittance.” }
‘‘The beau-ideal which we place before us in the
arts of spinning and weaving,” said an inhabitant of the
INTRODUCTION. XVil
South to Michelet, ‘‘is the beautiful hair of a woman:
the softest wool, the finest cotton, is very far from
realizing it.” The Southerner seemed to forget that
this soft wool, as well as this fine cotton, was not the
product of our manufacturers any more than the
woman’s hair.
Were these animal machines to sustain injury, or
even to be idle for a certain time, we should be reduced
to have nothing wherewith to cover our shoulders : -the
fine lady would have neither Cashmere shawl, silk, nor
velvet in her wardrobe; we should have neither flannel
nor cloth to make our clothes; the herdsman even
would not have his goat’s skin to protect him from the
inclemency of the season. Thanks to the animal which
gives us his flesh and his fleece, we are able to leave the
southern regions, to brave the rigour of other climes,
and establish ourselves side by side with the reindeer
and the narwhal, in the midst of eternal snow.
We have our science and our steam-engines, of which
we are justly proud; the animals have only their simple
instinct to enable them to fabricate their marvellous
tissues, and yet they succeed better than ourselves.
The so-called blind forces of nature produce thread, the
use of which the genius of man seeks in vain to super-
sede; and we do not even dream of entering into com-
petition with these living machines which we daily crush
under our feet.
All these occupations are openly carried on; and if
there are some which are honest, it may be said that
there are others which deserve another character. In
the ancient as well as the new world, more than one
animal resembles somewhat the sharper leading the
XVlll INTRODUCTION.
life of a great nobleman; and it is not rare to find, by
the side of the humble pickpocket, the audacious
brigand of the high road, who lives solely on blood and
carnage. A great proportion of these creatures always
escape, either by cunning, by audacity, or by superior
villany, from social retribution.
But side by side with these independent existences,
there are a certain number which, without being para-
sites, cannot live without assistance, and which demand
from their neighbours, sometimes only a resting-place
in order to fish by their side, sometimes a place at their
table, that they may partake with them of their daily
food; we find some every day which used to be con-
sidered parasites, yet which by no means live at the
expense of their hosts.
When a copepode crustacean instals himself in the
pantry of an ascidian, and filches from him some dainty
morsel, as it passes by; when a benevolent animal
renders some service to his neighbour, either by keeping
his rack clean, or removing detritus which clogs certain
organs, this crustacean or this animal is no more a para-
site than is he who cowers by the side of a vigilant and
skilful neighbour, quietly takes his siesta, and is con-
tented with the fragments which fall from the jaws of
his companion. We may say the same thing of the fish
which, through idleness, attaches itself, like the remora,
to a neighbour who swims well, and fishes by his side
without fatiguing his own fins.
The services of many of these are rewarded either in
protection or in kind, and mutuality can well be exercised
at the same time as hospitality.
Those creatures which merit the name of parasites
INTRODUCTION. X1x
feed at the expense of a neighbour, either establishing
themselves voluntarily in his organs, or quitting him
after each meal, like the leech or the flea.
But when the larva of an ichneumon devours, organ
after organ, the caterpillar which serves him as a nurse,
and at last eats her entirely, can we call him a parasite?
According to Lepelletier de Saint-Fargeau, who has so
successfully treated these questions, the parasite is he
who lives at the expense of another, eating that which
belongs to him, but not devouring his nurse herself. Nor
is the ichneumon a carnivorous animal, for the true
beast of prey cares nothing at any period of his exist-
ence for the life of his victim. .
True parasites are very commonly found in nature,
and we should be wrong were we to consider that they
all live a sad and monotonous life. Some among them
are so active and vigilant that they sustain themselves
during the greater part of their life, and only seek for
assistance at certain determinate periods. They are
not, as has been supposed, exceptional and strange
beings, without any other organs than those of self-
preservation. There is not, as was formerly supposed,
a class of parasites, but all the classes of the animal
kingdom include some among their inferior ranks.
We may divide them into different categories. -
In the first of these we will place together all those
which are free at the commencement of their life, which
swim and take their sport without seeking assistance
from others, until the infirmities of age compel them to
retire into a place of refuge. They live at first like true
Bohemians, and are certain of getting invalided at last
in some well-arranged asylum. Sometimes both the
XX INTRODUCTION.
male and female require this assistance at a certain age;
with others it is the female only, as the male continues
his wandering life. In some cases, the female carries
her partner with her, and supports him entirely during
his captivity; her host nourishes her, and she in her
turn feeds her husband. We find few female gill-
suckers which have not with them their Lilliputian
males, which, like a shadow, never quit them. But we
also find males, living as parasites of their females,
among those curious crustaceans known by the name of
cirrhipeds. All the parasitical crustaceans are placed in
this first category.
We find others, the ichneumons for example, which
are perfectly at liberty in their old age, but require pro-
tection while young. There are many of these, which
as soon as they escape from the egg, are literally put
out to nurse ; but from the day when they cast off their
larval robe, they are no longer under restraint, but,
armed cap-a-pie, they rush eagerly in quest of adven-
ture, and die like others on the high road. In this
category are generally found parasitical hymenopterous
and dipterous insects.
Other kinds are lodgers all their lives, though they
change their hosts, not to say their establishment, ac-
cordingly to their age and constitution. As soon as they
quit the egg, they seek for the favours of others, and all
their itinerary is rigorously traced out for them before-
hand. Fortunately we are at present acquainted with
the halting-places and magazines of a great number of
those which belong to the order of cestode and trema-
tode worms. These flat and soft worms begin life
usually as vagabonds, aided by a ciliary robe which
INTRODUCTION. XX1
serves as an apparatus for locomotion; but scarcely
have they tried to use their delicate oars, before they
demand assistance, lodge themselves in the body of the
first host that they meet, whom they abandon for
another living lair, and then condemn themselves to
perpetual seclusion.
That which adds to the interest inspired by these
feeble and timid beings is, that at each change of abode,
they change also their costume; and that when they
have reached the limit of their peregrinations, they
assume the virile toga—we had almost said, the wedding
robe. The sexes appear only under this later envelope ;
up to this period they have had no thoughts of the cares
of afamily. It has always been somewhat difficult to
establish the identity of those persons who frequent the
public saloons one day, and are found on the next in the
most obscure haunts, dressed as mendicants. Most of
the worms which have the form of a leaf or a tape
give themselves up to these peregrinations, and those
which do not arrive at their last stage, die usually with-
out posterity.
It is interesting to remark that these parasitical
worms do not inhabit the various organs of their
neighbours indiscriminately, but all begin their life
modestly in an almost inaccessible attic, and.end it in
large and spacious apartments. At their first appear-
ance they think only of themselves, and are contented
to lodge, as scolices or vesicular worms, in the connective
tissue of the muscles, of the heart, of the lobes of the
brain, or even in the ball of the eye; at a later stage,
they think of the cares of a family, and occupy large
vessels like the digestive or respiratory passages, always
XXil INTRODUCTION.
in free communication with the exterior; they have a
horror of being enclosed, and the propagation of their
species requires access to the outer air.
In the last category are found those Lh need
assistance all their lives; as soon as they have pene-
trated into the body of their host, they never remove
again, and the lodging which they have chosen serves
them both as a cradle and a tomb.
Some years since, no one suspected that a parasite
could live in any other animal than that in which it was
discovered. All helminthologists, with few exceptions,
looked upon worms in the interior of the body as formed
without parents in the same organs which they occupy.
Worms which are parasites of fish, had been seen a
long time before this in the intestines of various birds:
experiments had even been made to satisfy observers of
the possibility of these creatures passing from one body
to another; but all these experiments had only given a
negative result, and the idea of inevitable transmigration
was so completely unknown that Bremser, the first hel-
minthologist of his age, raised the cry of heresy, when
Rudolphi spoke of the ligule of fishes which could
continue to live in birds.
At a period nearer to our own times, our learned
friend, Von Siebold, deservedly called the prince of hel-
minthologists, was entirely of this opinion, and com-
pared the cysticercus of the mouse with the tape-worm
of the cat, considering this young worm as a wandering,
sick, and dropsical being.
In his opinion, the worm had lost its way in the
mouse, as the tenia of the cat could live only in the cat.
Flourens considered it a romance when I myself an-
INTRODUCTION. XX1ll
nounced to the “ Institut de France,’ that cestode worms
must necessarily pass from one animal to another in
order to complete the phases of their evolution.
At the present time, experiments respecting these
transmigrations are repeated every day in the labora-
tories of zoology with the same success; and Mons. R.
Leuckart, who directs with so much talent the Institute
of Leipzig, has discovered, in concert with his pupil
Mecznikow, transmigrations of worms accompanied by
changes of sex; that is to say, they have seen nematodes,
the parasites of the lungs of the frog, always female or
hermaphrodite, produce individuals of the two sexes
which do not resemble their mother, and whose habitual
abode is not in the lungs of the frog but in damp earth.
In other worcs, let us imagine a mother, born a widow,
who cannot exist without the assistance of others, pro-
ducing boys and girls able to provide for themselves.
The mother is parasitical and viviparous, her daughters
are, during their whole life, free and oviparous.
This observation leads us to another sexual singu-
larity, lately observed, of males and females of different
kinds in one and the same species, and which give birth
to progeny which do not resemble each other; the same
animals, or rather the same species, proceed from two
different eggs fecundated by different spermatozoids.
Now that these transmigrations are perfectly known
and admitted, the starting-point of the inquiry has been
so entirely forgotten that the honour of the discovery
has been frequently attributed to fellow-workers, who
had no knowledge of it till the demonstration had been
completed, and the new interpretation generally accepted.
But let us return to our subject.
XXIV INTRODUCTION.
The assistance rendered by animals to each other is
as varied as that which is found amongst men. Some
receive merely an abode, others nourishment, others
again food and shelter; we find a perfect system of
board and lodging combined with philozoic institutions —
arranged in the most perfect manner. But if we see by
the side of these paupers, some which render to one
another mutual services, it would be but little flattering to
them to eall all indiscriminately either parasites or mess-
mates (commensaux). We think that we should be more
just to them if we designated the latter kinds mutualists,
and thus mutuality will take its place by the side of mess-
table arrangements (commensalism) and of parasitism.
It would also be necessary to coin another name for
those which, like certain crustaceans, or even some birds,
are rather guests which smell out a feast from afar
(pique-assiettes) than parasites; and for others which
repay by an ill turn the assistance which they have
received. And what name shall we give to those which,
like the plover, render services which may be compared
to medical attendance ?
This bird in fact performs the office of dentist to the
crocodile. A small species of toad acts as an accoucheur
to his female companion, making use of his fingers as
a forceps to bring the eggs into the world. Again, the
pique-beuf performs a surgical operation, each time
that he opens with his lancet the tumour which encloses
a larva in the midst of the buffalo’s back. Nearer home,
we see the starling render in our own meadows the
same service as the pique-beuf (Buphaga) in Africa; and
we may see that among these living creatures there is
more than one speciality in the healing art.
INTRODUCTION. XXV
We must not forget that the occupation of a grave-
digger is equally general in nature, and that it is never
without some profit to himself or his progeny that this
sloomy workman inters the bodies of the dead. Certain
animals have an occupation analogous to that of the
shoeblack or the scourer, and they freshen up with care,
and even with a kind of coquettish pleasure, the toilet
of their neighbours.
And how must we designate the birds known by the
name of stercorarie, which take advantage of the
cowardice of sea-gulls in order to live in idleness ? It is
useless for the gulls to trust to the strength of their wings,
the stercorariz in the end compel them to disgorge their
food in order that they may partake of the spoils of their
fishery. When followed up too closely, these timid birds
throw up the contents of their crop, to render themselves
lighter, like the smuggler who finds no means of safety
except in abandoning his load.
We must not, however, be too hard upon all this class,
since very often, as in the case of the gnat, it is only
one of the sexes which seeks a victim.
All animals usually live for the passing day; and
yet there are some which practise economy, which are
not ignorant of the advantages of the savings bank, and,
like the raven and the magpie, think of the morrow, to
lay up in store the superfluity of the day’s provision.
As we have before said, this little world is not always
easy to be known, and in its societies, to which each
brings his capital, some in activity, others in violence or
in stratagem, we find more than one Robert Macaire who
contributes nothing, and takes advantage of all. Every
species of animal may have its parasites and its mess-
XXV] INTRODUCTION.
mates, and each may perhaps have some of different
sorts, and in diverse categories.
But whence come those disgusting beings, whose
name alone inspires us with horror, and which instal
themselves without ceremony, not in our dwellings, but
in our organs, and which we find it more difficult to
expel than rats or mice? They all derive their existence
from their parents.
The time has passed when a vitiated condition of the
humours, or the deterioration of the parenchyma was
considered a sufficient cause for the formation of para-
sites, and when their presence was regarded as an
extraordinary phenomenon resulting from the morbid dis-
positions of the organism. We have reason to hope that
this language will, during the next generation, have
entirely disappeared from works on physiology and
pathology. Neither the temperament nor the humours
have any influence on parasites, and they are not more
abundant in delicate individuals than in those who enjoy
the most robust health. On the contrary, all wild
animals harbour their parasitical worms, and the greater
part of them have not lived long in captivity, before
nematode and cestode worms completely disappear. It
is only the imprisoned parasites which do not desert
them.
All these mutual adaptations are pre-arranged, and
as far as we are concerned, we cannot divest ourselves of
the idea that the earth has been prepared successively
for plants, animals, andman. When God first elaborated
matter, He had evidently that being in view who was
intended at some future day to raise his thoughts to
Him, and do Him homage.
INTRODUCTION. XXVil
This is the answer which I would give to the ques-
tion recently propounded by Mons. L. Agassiz. ‘‘ Were
the physical changes to which our globe has been sub-
jected effected for the sake of the animal world, con-
sidered in its relations from the very beginning, or are
the modifications of animals the result of physical
changes? in other words, has the earth been made and
prepared for living beings, or have living beings been ag
highly developed as was possible, according to the phy-
sical vicissitudes of the planet which they inhabit ?
This question has always been discussed, and that
science which cannot look beyond its scalpel, will never
succeed in resolving it. Hach one must seek by his own
reason the solution of the great problem.
When we see the newly-born colt eagerly seeking for
its mother’s teats, the chick as soon as it is hatched
beginning to peck, or the duckling seeking its puddle of
water, can we recognize anything but instinct as the
cause of these actions, and is not this instinct the libretto
written by Him who has forgotten nothing ?
The statuary who tempers the clay from which to
make his model, has already conceived in his mind the
statue which he is about to produce. Thus it is with the
Supreme Artist. His plan for all eternity is present to
His thought. He will execute the work in one day, or in
a thousand ages. Time is nothing to Him; the work is
conceived, it is created, and each of its parts is only the
realization of the creative thought, and its predetermined
development in time and space.
‘The more we advance in the study of nature,” says
Oswald Heer in ‘‘ Le Monde primitif” which he has just
published, ‘the a profound also is our conviction, that
XXVIll INTRODUCTION.
belief in an Almighty Creator and a Divine Wisdom, who
has created the heavens and the earth according to an
eternal and preconceived plan, can alone resolve the
enigmas of nature, as well as those of human life. Let
us still erect statues to men who have been useful to
their fellow-creatures, and have distinguished themselves
by their genius, but let us not forget what we owe to Him
who has placed marvels in each grain of sand, a world
in every drop of water.”
At first we shall treat of animal messmates, secondly
of mutualists, and thirdly of parasites.
ANIMAL PARASITES
AND MESSMATES.
CHAPTER I.
ANIMAL MESSMATES.
THE messmate is he who is received at the table of his
neighbour to partake with him of the produce of his day’s
fishing; it would be necessary to coin a name to desig-
nate him who only requires from his neighbour a simple
place on board his vessel, and does not ask to partake
of his provisions.
The messmate does not-live at the expense of his
host ; all that he desires is a home or his friend’s super-
fluities. The parasite instals himself either temporarily
or definitively in the house of his neighbour ; either with
his consent or by force, he demands from him his living,
and very often his lodging.
But the precise limit at which commensalism begins
is not always easily to be ascertained. There are
animals which live as messmates with others only at a
certain period of their lives, and which provide for their
own support at other times; others are only messmates
2, ANIMAL PARASITES AND MESSMATES.
under certain given circumstances, and do not usually
merit this appellation.
In the higher animals, this relation between them is
generally well known, and justly appreciated, but it is not
the same in the inferior ranks; and more than one
animal may pass for a messmate or a parasite, for a
robber or for a mendicant, according to the circum-
stances under which he isobserved. The sharper passes
for an honest man as long as he has not been taken in
flagrante delicto. Thus; in order to be just, we must
carefully examine the indictment, and not pronounce
sentence without strict examination.
The greater part of those animals which have estab-
lished themselves on each other, and live together on
a good understanding and without injury, are wrongly
classed as parasites by the generality of naturalists.
Now that the mutual relations of many of these are
better understood, we know many animals which unite
together to render each other mutual assistance; while
there are others which live like paupers on the crumbs
which fall from the rich man’s table. There are many
relations between the different species which can be dis-
covered only after minute examination, but which have
recently been appreciated with greater impartiality.
Animal messmates are rather numerous, and com-
mensalism has been observed, not only in animals of the
present age, but in those of the primary epoch. Wyville
Thomson explained to me, while I was myself his mess-
mate at Edinburgh, at the meeting of the British Asso-
ciation in 1871, that the polyps of the Silurian age
already practised it. We do not class among animal
messmates those living creatures which, like the birds
ANIMAL MESSMATES, 3
which we keep in cages, charm the ear with their song,
or which, in spite of our care, live at the expense of our
pantry; we will only refer to veritable messmates, which,
sometimes through weakness of constitution, sometimes
for want of activity, can neither feed themselves nor
bring up their family without seeking help from their
neighbours.
There are some free messmates which never renounce
their independence, whatever may be the advantages
which their Amphitryon enjoys; they break their alliance
with him for the slightest motive of discontent, and go
and seek their fortune elsewhere. Their susceptibility
or their love of change guides them. They are recog-
nized by their fishing implements or their travelling
gear, which they never lay aside. These free messmates
are the more numerous. The others, the fixed mess-
mates, instal themselves with a neighbour, and live at
their ease, having completely changed their dress, and
renounced for ever an independent life. Their fate is
thenceforward bound to him who carries them.
Under these two categories we shall cite several ex-
amples, and glance at the differences which the various
classes of the animal kingdom present in this respect,
beginning with the higher ranks.
4 ANIMAL PARASITES AND MESSMATES,
CHAPTER II.
FREE MESSMATES.
We meet with free messmates in various classes of
the animal kingdom. They sometimes mount on the
back of a neighbour, sometimes occupy the opening of
the mouth, the digestive passages, or the exit for the
excreta; at times they place themselves under the
shelter of the cloak of their host, from whom they
receive both aid and protection.
Among the vertebrates, there are few except fishes
which merit a place here ; it is only amongst these that
we meet with species at the mercy of others, and
dependent on acolytes, which are in every respect
inferior to themselves.
An interesting messmate belonging to this first
category is a fish of graceful form, named donzelina,
which goes to seek its fortune in the body of a holo-
thuria. Naturalists have long known it under the name
of Fierasfer. It has a long body like that of an eel,
entirely covered with small scales; and as it is quite
compressed, it has been compared to the sword which
conjurors thrust into their cesophagus. They are found
in different seas, and all have similar habits. This fish
is lodged in the digestive tube of his companion, and,
FREE MESSMATES. 5
without any regard for the hospitality which he receives,
he seizes on his portion of all that enters. The Fier-
asfer contrives to cause himself to be served by a
neighbour better provided than himself with the means
of fishing.
Dr. Greef, at present Professor at Marbourg, found
at Madeira a holothuria of a foot in length, in which a
vigorous Fierasfer lived in peace. Quoy and Gaimard,
in the account of their voyage round the world, have
remarked long since, that the Ficrasfer hornet is found
in the Stichopus tuberculosus.
The holothurize seem to exist under very advan-
tageous conditions in this respect, since we see Fier-
asfers, which are themselves tolerable gluttons, accom-
panied by Palemons and Pinnotheres in the same
animal. Professor C. Semper has seen holothurize
in the Philippine Islands which bore a considerable
resemblance, in this respect, to an hotel with its
table d’hote.
These singular fishes have been long noticed, but it
was not till recently that their presence in a host so low
in the scale as a holothurian could be explained.
But if naturalists are agreed as to the bond which
unites these fishes to the holothurie, they do not agree
as to the organs which they inhabit in their living hotel.
Do they lodge in the digestive cavity of the holothuria,
or do they inhabit the arborescent respiratory processes
which open at the posterior extremity of the body ?
Until recently it was thought that it was in their
stomach, but a doubt has arisen. Professor Semper,
who: has studied these animals with particular care
at the Philippine Islands, had the curiosity to open
6 ANIMAL PARASITES AND MESSMATES.
the stomach of some of them, and found there, not the
animals taken by the holothurie, but the remains of
its respiratory processess which they were in the act of
digesting. Is it then merely a messmate? We must
have more information on this point; and if it were not
accidentally that the fierasfer swallowed the walls of the
compartment in which he was lodged, he ought rather
to take his place among parasites. Though it lodges in
the respiratory processes, as the learned professor at
Wurtzburg asserts, the fierasfer may also be a mess-
mate after the fashion of so many others which inhabit
the neighbourhood of the rectum, in order the more con-
veniently to snap up those animals which are attracted
by the odour.
The fierasfers are not the only fishes which seek
assistance from the holothurie; a species lives at
Zamboanga, to which the specific name of Scabra has
been given, and in the stomach of which, says Mons.
Johannes Muller, usually lives a myxinoid fish, called
Enchelyophis vermicularis. Unfortunately, we are not
told in what part of the stomach it resides; for all is
stomach in these animals.
It is less degrading for a fish to ask assistance from
one in his ownrank. The Mediterranean offers a curious
instance of this. Risso saw at Nice, at the commence-
ment of this century, the monstrous fish known under the
name of Beaudroie (the angler, or fishing-frog) lodging
in its enormous branchial sac a fish of the family of the
Murenide, the Apterychtus ocellatus. He is found there
evidently under the condition of a messmate. Although
the eels generally get their living easily, the Angler pos-
sesses fishing implements which are wanting in them, and
FREE MESSMATES. vf
when both of them are immersed in the ooze, it carries
on a fishery sufficiently abundant to enable it to share
the spoil with others. This same angler lives in the
northern seas, and there it harbours an amphipod crus-
tacean, which until lately has escaped the vigilance of
carcinologists. We shall speak of it further on.
Dr. Collingwood saw a sea anemone in the Chinese
Sea, which was not less than two feet in diameter, and
in the interior of which lodges a very frisky little fish,
the name of which he could not tell.
Lieut. de Crispigny has observed a sea anemone
(Aectinia crassicornis) living on good terms with a
malacopterygian fish, the Premnas biaculeatus. This
fish penetrates into the interior of the anemone; the
tentacles close round it, and it lives thus for a consider-
able time enclosed as in a living tomb. Mons. de
Crispigny has kept these animals alive for more than a
year, in order to make careful observations on them. A
fish known by the name of Oxybeles lumbricoides has been
also found in the Indian Seas, which modestly takes up
his quarters in a star-fish (Asterias discoida). Another
case of commensalism has been made known to us by
Professor Reinhardt of Copenhagen. A siluroid of Brazil,
of the genus Platystoma, a skilful fisherman, thanks to
his numerous barbules, lodges in the cavity of his mouth
some very small fishes, which were for a long time con-
sidered as young siluroids; it was supposed that the
mother brought her progeny to maturity in the cavity
of the mouth, as marsupials do in the abdominal pouch,
or as some other fishes do. These messmates are per-
fectly developed and adult, but instead of living on the
produce of their own labour, they prefer to instal them-
S$ ANIMAL PARASITES AND MESSMATES.
selves in the mouth of an obliging neighbour, and to take
their tithes of the succulent morsels which he swallows.
This little fish has received the name of Stegophilus
insidiatus. We see that in the animal world it is not
always the great which take advantage of the litle.
Still, let us not be deceived; there are fishes in the
latitude of the Island of Ceylon which really hatch their
eggs in the cavity of the mouth, and we have seen some
in the museum at Edinburgh, labelled with the name of
Arius booket. Louis Agassiz has made the same observa-
tion on a fish of the Amazon, which has also been
recognised by Jeffreys Wyman. One fish wraps up its
eggs in the fringes of its branchiz, and protects them till
they are hatched; another lays its eggs in holes hollowed
out by itself in the steep banks of the river, and protects
the young ones after they are hatched.
To hatch the eggs in the mouth is not more extra-
ordinary than to hatch them in any other part of the
body. The Sygnathide hatch theirs in a pouch behind
the anus; and it is a curious circumstance that the
females do not undertake this duty. The males alone
carry their progeny with them. This recalls to our
recollection that curious example of the birds known
under the name of Phalaropes, among which the males
only hatch the eggs. The female of the cuckoo abandons
her eggs, and entrusts them to the female of another bird.
The cuckoo suggests to us the mound-making Mega-
pode and the Talegalla of Latham, both of which
inhabit Australia; these birds deposit their eggs in an
enormous mass of leaves or grass, which grows warm
by decomposition, and the temperature of which is great
enough to hatch them. The young ones when they come
FREE MESSMATES, 9
out of the egg are sufficiently developed to be able to
provide for their own wants, and to do without a mother’s
care.
To return to our animal messmates: let us notice
the result of the observations of a learned and skilful
naturalist who has rendered great services to ichthyology.
Dr. Bleeker has described a still more remarkable
association in the Indian seas; it is that of a crustacean,
the Cymothoa, taking advantage of a fish known under
the name of Stromatea ; too imperfectly organized to fish
for itself at large, but more skilful in snapping up all
that comes within its reach, it makes its home in the
buccal cavity of the Stromatea.
But of all crustaceans, the most cruel is the isopod
named Ichthyoxena, which hollows out for itself and its
female a large dwelling-place in the coats of the stomach
of a cyprinoid fish. We will return again to these
examples.
The Physaliz, those charming living nosegays of the
tropical regions, also give lodging in their cavities, and in
the midst of their long cirrhi, to little adult and perfect
fishes, belonging to the family of the Scombridz, a family
to which are attached the tunny and the mackerel. These
sea-butterflies flutter away their indolent existence at the
expense of their host. Voyagers tell us that they have
seen them by dozens concealed in these animated fes-
toons. Mons. Al. Agassiz has mentioned, in his illus-
trated catalogue, another fact, quite as extraordinary,
observed in the Bay of Nantucket, in the United States ;
it relates to a nocturnal Pelagia (Dactylometra quinque-
cirra, Ag.) always accompanied, not to say escorted, by
a species of herring. The two neighbours constitute
10 ANIMAL PARASITES AND MESSMATES.
together an association which probably redounds to the
advantage of both.
Without quitting our own sea-coast, we find an asso-
ciation of the same kind between young fishes (Caranz:
trachurus) and a beautiful medusa (Chrysaora isocela).
This sea nettle often encloses several young specimens
of Caranx, which we are surprised to see issuing full of
life from the transparent bodies of these polyps. Indeed,
it is not rare to find other fishes in the meduse. Dr.
Gunther, who has arranged with so much care the rich
collection of fishes in the British Museum, has shown us
some specimens of the Labraxz lupus, and of the Gaster-
osteus, which had been obtained from the interior of
different meduse; and these associations have been also
remarked by various distinguished observers, among
whom we may mention Messrs. Sars, Rud. Leuckart, and
Peach. The captain of the frigate Jowan, when in the
Indian Sea, on October 26th, 1871, in 13° 20’ N. lat.,
and 60° 30’ E. long., that is to say, about 200 leagues
to the west of the Laccadive Islands, saw, in very fine
weather, the sea, which was at that time very calm, covered
with meduse, and the greater part of these were escorted
by many little fishes of the genus Ostracion, the species of
which he was unable to ascertain. It is probable that
the school of medusz set in motion certain animals which
are eagerly sought after by the Ostracions.
The Pilot is a fish of which much has been recorded ;
fishing for it is one of the principal recreations of sailors
during their long voyages. Some assure us that it
snaps off the bait, without touching the murderous hook
which threatens the shark; and as it never quits its
companion, others have supposed that it lives on the
FREE MESSMATES. ll
morsels abandoned by it. Neither of these suppositions
is correct; and as the shark does not need its services to
point out the danger, we must content ourselves with
mentioning this curious association without endeavour-
ing to.explain it.
In fact, we have had the opportunity of examining
many well-preserved specimens, the stomach of which
contained potato parings, the carapaces of crustaceans,
the débris of fishes, marine plants (fuci), and a piece of
cut fish, which had evidently served as a bait. The pilot
does not, therefore, live on the leavings of his companion,
but on his own industry, and doubtless finds some advan-
tage in piloting his neighbour. Through the great
kindness of Dr. Gunther we have been able to make
this interesting examination in the rich galleries of the
British Museum. We desire to take this opportunity of
expressing our gratitude to this learned man and to his
illustrious colleagues, who have the direction of that vast
establishment, which is ever open to those who labour
for the advancement of science.
The pilot has sometimes been confounded with a very
different fish, which does not merely remain in the neigh-
bourhood of the shark, but establishes itself upon him,
and moors himself to him by the aid of a particular
apparatus, for a longer or shorter time; we may even
say during the whole of the voyage. This is the Remora.
Is this fish the messmate of the shark to which he is
attached? As in the case of the pilot, an examination
alone could decide the question. We have opened at the
British Museum the stomachs of several remoras of
different sizes, and we have been able to ascertain that
they also fish on their own account; their food was
12 ANIMAL PARASITES AND MESSMATES.
composed of morsels of fish which had served as bait,
of young fish swallowed whole, and of some remains of
crustacea. ‘The remora is simply anchored to his host,
and asks from him nothing but his passage. He is
contented, like the pilot, to fish in the same waters as
the shark which transports him. Sailors, even now, are
convinced that if any one of these remoras should attach
itself to the ship, no human power could cause it to
advance, and that it must of necessity stop. It is certain
that the fishermen of the Mozambique Channel take ~
advantage of this faculty, to fish for turtles and certain
large fish. They pass through the tail of the remora a
ring to which a cord is attached, and then send it in
pursuit of the first passer-by which they consider worthy
to be caught. This kind of fishing resembles in some
degree the sport of hawking with falcons.
So extraordinary a being could not fail to attract the
attention of those among the ancients who were students
of nature. Pliny assures us that the remora was used
in the preparation of a philtre capable of extinguishing
the flames of love.
There must be many free animal messmates among
insects, and entomologists should make them known;
for example, many of them live with ants, as the Psela-
phide and Staphylinide. Certain hairs of these insects,
it is said, secrete a sweet liquid of which ants partake
ereedily. If we may believe a skilful observer, Mons.
Lespés, there are some among them, as the Clavigers,
which in exchange for the services which they render are
fed by the ants themselves. We may also mention the
larve of the Meloé, which seem to live as parasites, and
the true nature of which was so long unknown.
FREE MESSMATES. 13
The females of the Meloé lay their eggs near the
ranunculus and other plants whose flowers are regularly
visited by bees. After these are hatched, the larve
ascend into the flowers and wait patiently till a bee takes
them on his back, and carries them into the interior
of the hive. This insect was formerly known under
the name of the bee-louse, but this appellation is im-
proper, for the bee is not the host of the meloé, but simply
its beast of burden. According to recent observations,
flies perform the same office for Chelifers, and certain
aquatic and land coleoptera for several kinds of acaride.
In the class of animal messmates we find also a
coleopterous insect that lodges in a manner similar to
the paguri, of which we shall presently speak. The
female of the Drilus, a species allied to glowworms,
attacks the snail, and when it has devoured it, instals
itself in the shell, to pass through its metamorphoses ;
when necessary, it frequently changes its shell and chooses
successively more spacious lodgings. like a_ true
Sybarite, the drilus weaves a curtain of tapestry before
the entrance of its habitation, and remains there peace-
ably surrounded by the vestment of its youth.
Remarkable examples of free messmates are found
more especially among crustaceans. It is well known
that this class includes lobsters, crabs, prawns, and those
lesions of small animals which serve as the police of the
sea-shore, purifying the waters of the ocean of all or-
eanic matters, which otherwise would corrupt them.
They do not, like insects, shine with variegated colours ;
their forms are hardy and varied, and they are often
pleasing on account of the singularity of their move-
ments. Professor Verrill has recently studied some of
14 ANIMAL PARASITES AND MESSMATES,
these creatures, and has clearly shown how interesting
they are, not only to naturalists, but to people in
general.
Crustaceans and worms furnish the greatest number
of paupers and infirm individuals; and a great many of
them need the continual assistance of their neighbours
to enable them to get their living. While other animals
advance towards perfection as they grow older, it is far
different with many crustaceans, and we should be
tempted to refer to the vegetable kingdom many of them
at the very period when they are approaching the adult
condition. Cuvier placed all the class of cirrhipedes
among the mollusca, and the lerneans among the
worms. Many of these animals which are but indif-
ferently adapted to live without help from others, have
recourse to benevolent neighbours; from one they seek
only shelter, from another a part of his booty, from
a third both an asylum and protection. They are often
reduced to a mere skin; everything else has disappeared,
and there remains no proper organ except that which is
necessary for the reproduction of the species. Corpulent,
blind, impotent, legless cripples, their existence is more
precarious than that of those miserable mutilated beings
found in our cities; they only live on the blood of the
neighbour which gives them an asylum. Yet when they
first quit the ege they are all free; they frisk, they swim
with the rapidity of lightning, and at the close of life
we find them deformed, and crouched in some living
refuge, as if a foul leprosy had atrophied within them all
the organs which served as a means of communication
with the outer world. Parasites and messmates, fur-
nished at first with the same kind of limbs and the
FREE MESSMATES. 15
same habits, can sometimes only be distinguished from
each other when we have made our observations on
them in their first swaddling clothes. The child has
given a clue to the history of the old man.
We will not examine these animals in all the details
of their private life, and yet we are strongly tempted to
confess to our readers some of the indiscreet acts of which
we have been guilty, in watching them while changing
their dress. Notwithstanding their shyness and their
desire to escape observation during the moulting period,
we have more than once made observations on them
while quitting their garment which has become too small.
The old tunic generally splits down the back, and falls
off all in one piece as it gives the animal egress. The
crustacean is extended quite soft and supple by the side
of its rigid carapace.
Of all the free crustacean messmates, one of the
most interesting, though among the smallest of them, is
a tiny crab, about as large as a young spider, which
lives in mussels, and which has been often accused,
though evidently wrongfully, as the cause of the indis-
position so well known by those who are fond of this
mollusc. Very many of them have been seen within the
last few years, and yet accidents have been very few.
The mussels themselves are guilty; they produce on
some persons an injurious effect, through idiosyncracy.
We have at least a word to serve as an explanation, and
at present we must content ourselves with it.
Under what conditions do those crabs, called by
naturalists Pinnotheres, and which we do not find else-
where, inhabit mussels? Are they parasites, pseudo-
parasites, or messmates? It is not a taste for voyaging
16 ANIMAL PARASITES AND MESSMATES.
which tempts them, but the desire of having always a
secure retreat in every place. The pinnothere is a
brigand who causes himself to be followed by the cavern
which he inhabits, and which opens only at a well-known
watchword. The association redounds to the advantage
of both; the remains of food which the pinnothere aban-
dons are seized upon by the molluse. It is the rich
man who instals himself in the dwelling of the poor, and
causes him to participate in all the advantages of his
position. The pinnotheres are, in our opinion, true
-messmates. They take their food in the same waters as
their fellow-lodger, and the crumbs of the rapacious
crabs are doubtless not lost in the mouth of the peaceful
mussel. There is no doubt that these little plunderers
are good lodgers, and if the mussels furnish them with
an excellent hiding-place and a safe lodging, they them-
selves profit largely by the leavings of the feast which
fall from their pincers. Little as they are, these crabs
are well furnished with tackle, and advantageously
placed to carry on their fishery in every season. Con-
cealed in the bottom of their living dwelling-place (a
den which the mussel transports at will) they choose
admirably the moment and the place to rush out to the
attack, and always fall on their enemy unawares. Some
of these pinnotheres live in all seas, and inhabit a
great number of bivalve molluscs. The northern seas
contain a large species of Modiola (Modiola Papuana)
which is especially found in deep and almost inaccessible
parts, and which always encloses a couple of pinno-
theres about the size of a hazel-nut. We have opened
hundreds of these modiole, and we have never met with
any without their crabs. We have long since deposited
FREE MESSMATES. ive
some specimens of these pinnotheres in the galleries of
the Natural History Museum at Paris.
The large mussel, which furnishes fine pearls (Avicula
margaritifera), lodges also pinnotheres of a particular
species by the side of another messmate more allied to
a lobster than a crab. It is not even impossible that
these crustaceans, with other messmates or parasites,
contribute to the formation of pearls, since these gems,
so highly prized in the fashionable world, are only the
result of vitiated secretions, and are usually the result of
wounds.
We also meet with a little crab (Ostracotheres tri-
dacnz, Ruppel) in the acephalous mollusc, whose immense
shell sometimes serves as a vessel for holy water ; and it
lives doubtless in many other bivalves which have not
yet been examined.
Dr. Léon Vaillant has written a very interesting
memoir on the Tridacne, and informs us that the crab
takes shelter in their branchial chamber. Therefore,
since the molluscs live only on vegetable substances,
while the Ostracotheres feed entirely on animal matter,
Mons. Vaillant supposes that the latter take their choice
of the food as it enters, and seize on its passage that
which suits them best. Mr. Peters, during his abode
on the coast of Mozambique, studied a great many
of these acephala and pearl-mussels, and found their
interior inhabited by three crustacean decapods, a pin-
nothere, and two macroure allied to the Pontonia, to
which he has given the name of Conchodytes; the
Conchodytes tridacne inhabits the Zridacna squamosa ;
the Conchodytes mcleagrine, as its specific name indicates,
lives in the shell of the pearl-mussel.
18 ANIMAL PARASITES AND MESSMATES.
Professor Semper has recently observed pinnotheres in
holothurians at the Philippine Isles, and Mons. Alphonse
M. Edwards has described some from New Caledonia
(P. Fischerit) ; so that these little crabs, the friends of the
molluscs, are known in both hemispheres.
Do not these conditions seem to authorize the con-
clusion that the same thought has presided over the
appearance of all living creatures; that they have all
come into existence, not according to the chance ar-
rangement of surrounding media, but according to the
laws established from the very origin of all things ?
The shell which lodges both these pinnotheres, in the
Mediterranean as well as the Atlantic, is a large acepha-
lous mollusc, known under the name of Jambonneau
(a small ham or gammon), and which, according to
Aristotle, harbours two different kinds of messmates.
This illustrious natural philosopher also described a Pon-
tonia (Pontonia custos, Guérin—P. Pyrrhena, M. Edw.)
about an inch and a half long, of a pale rose colour,
more or less transparent, and which lives with its com-
panion, the pinnothere, in the cavity of the Pinna
marina. This is the same animal which a naturalist of
the last century named the Cancer custos.
We have wished to ascertain whether Pliny knew
these crustaceans. He has spoken of them in the fol-
lowing terms :—‘‘ The Chama is a clumsy animal with-
out eyes, which opens its valves and attracts other fishes,
which enter without mistrust, and begin to take their
pastime in their new abode. The pinnothere seeing his
dwelling invaded by strangers, pinches his host, who
immediately closes his valves, and kills one after another
these presumptuous visitors, that he may eat them at
his leisure.” )
FREE MESSMATES. 19
Cuvier did not believe that the pinnothere brought
any food to the molluse, since the latter, in his opinion,
lives entirely on sea-water.
Other zoologists regard the pinnothere as an intruder
whom chance has brought into this mysterious position.
Others again consider mussels as acquaintances possessed
of a very curious disposition, and that having no eyes,
they have interested in their fate this little crab, which is
perfectly provided with eyesight. In fact, in common
with other crustaceans of his species, he carries on each
side of his carapace, at the end of a movable stalk, a
charming little globe, provided with some hundreds of
eyes, which he can direct upon his prey, as the astro-
nomer turns his telescope on any point of the firma-
ment. These later naturalists consider, in fact, their
crab as a living journal which supplies his host with
the news of the day. Rumphius, a Dutchman, the
first who described the animal of the nautilus, also
understood the habits of pinnotheres. In his ‘‘Am-
boinche Rariteit Kamer,” published in 1741, he says
that these crustaceans inhabit always two kinds of shell-
fish, the Pinna and the Chama squamata. According to
him, when these molluscs have attained their growth,
one pinnothere (one only at least in the Chama) lives in
their interior and does not abandon its lodging till the
death of its host. Rumphius regards this crustacean as
a faithful guardian, fulfilling the duties of a door-keeper.
In 1638 he found actually two sorts of keepers: by the
side of a Brachyuron, carrying an embossed buckler,
slender in front, he discovered a Macrouron of the length
of his finger-nail, of a yellowish orange colour, semi-
transparent, with white and very slender claws. It is
x
20 ANIMAL PARASITES AND MESSMATES.
without doubt the same animal that Mons. Peters, of
Berlin, found on the coast of Mozambique, and of which
we have spoken before.
A little crab is known to live near the coast of Peru
(Fabia Chilensis, Dana), which exists under somewhat
different conditions. He chooses, not a bivalve mollusc,
but a sea-urchin (Huriechinus imbecillus, Verrill), and
lodges in the intestine, near its termination, so as to
seize as they pass by all those living creatures which are ~
attracted by the odour. Doubtless, the delicacy of our
sense of smell is disgusted by such a mode of seeking
food; but this predilection may have a reason with which
we are not acquainted. There are a considerable number
of other species which live under similar conditions.
On the coast of Brazil, my son found two couples of
crabs in the tube of a very long annelid, narrow at the
ends, and wide in the middle. The tube was too small
at the end to allow them to escape. These crustaceans
had, no doubt, penetrated thither before they had at-
tained their full size.
A crab of the family of the Maide conceals itself in
the substance of a polypidom very common in the Viti
Islands, in company with a gasteropod molluse, and
both of them assume the exact colour of the polypidom.
This is a new kind of mimicry. This crab is known by
the name of Pisa Styx, the gasteropod is a Cyprea, the
polyp is the Melithea ochracea. A decapod crustacean,
the Galathea spinirostris, seeks for a Comatula, the
colour of which it exactly imitates, and with which it
lives on the most friendly terms. :
The holothuriz, of which we have already spoken,
appear to afford an abode to many animals: indepen-
FREE MESSMATES. o1
dently of the Fierasfer, the Holothuria scabra of the
Philippine Islands regularly lodges in its interior a
couple, and sometimes, though rarely, a greater number
of pinnotheres belonging to two distinct species. They
choose this domicile at an early period, and must be highly
delighted with this obscure abode, since they are seen
no more, and when they have once entered never quit
this hying cavern. This observation is due to Professor
Semper, who has made us acquainted with so many
curious facts of the China Sea and the Pacific Ocean.
In the midst of the slender branches of a coral of the
Sandwich Islands, the Pzxcilopora cespitosa of Dana,
there lives a little crab (Hopalocarcinus marsupialis,
Stimpson), which is at last completely enclosed by the
vegetation of the coral. It only keeps up sufficient
communication with the exterior to enable it to procure
food. The coral, however, furnishes it nothing but a
resting-place in the midst of its tissues.
Among the Philippine Islands, also, a brachyurous
crustacean lives in the branchial cavity of one of the
Haliotide, and another on the body of a holothuria. On
the coasts of Brazil, F. Muller, during his abode at
Desterro, saw some Porcellane inhabiting star-fish, not
as parasites, as had been supposed, but as true mess-
mates. A crustacean possessed of but little generosity
is the Lithoscaptus of Mons. Milne-Edwards. Provided
with beak and claws for the purpose of attack, it instals
itself, sad to say, in the pantry of a medusa, and instead
of making use of its own weapons, takes advantage of
the perfidious nematocysts of its acolyte, in order to live
quietly at his expense.
Under the name of Asellus medusx, Sir J. G. Dalyell
=
oF ANIMAL PARASITES AND MESSMATES.
has made us acquainted with another messmate of the
medusx which greatly resembles an Ldothea.
Another kind of commensalism is that of the
Dromize. These crabs are of the ordinary size, and
lodge, from their earliest youth, under a growing family
of polyps, which increases with them. This colony has
for its principal foundation a living Alcyonium, which
covers the carapace, and as it develops, adapts itself
perfectly to all the inequalities of the cephalothorax ;_
one might consider it an integral part of the crab.
Sertulariz, Corynes, Algz, develop themselves on this
Aleyonium, and the Dromia, masked by this living rock
which it carries on its shoulders like the fabled Atlas,
marches gravely in pursuit of her prey. She has no
fear of arousing the attention of her enemies. The
ereatest vigilance cannot prevent the sudden attack of
these dangerous neighbours. There is in the Mediterra-
nean a species which sometimes comes to our coast.
They are also known in the Indian Seas and in the
Northern Pacific. Rumphius named the dromia Cancer
lanosus ; it is, said he, a crab which carries grass or
moss on its back. It is also mentioned by Renard.
Dana has observed a sea-anemone covering a crab in the
same manner as the Alcyonium does the dromia, and
which is not less dangerous. The mode of life of this
anemone has procured for it the name of Cancrisocia
expansa. In the north of California, a crab (Cryptoli-
thoides typicus) covers itself in the same manner with a
living cloak which hides it from view, and under cover
of which it surprises those whom it attacks. It has
already cleared the ground of its prey before any alarm
has been given to the neighbourhood.
FREE MESSMATES, 23
We should perhaps speak here of an association of
another kind, the nature of which it is difficult to ascer-
certain ; I refer to the little crab, the Turtle Crab of
Brown, which is met with in the open sea on the cara-
pace of turtles, and sometimes on sea-weeds. It may be
supposed that it takes advantage of the carapace of its
neighbour, in order to transport itself at little expense
into different latitudes, and it is asserted that the sight
of this crustacean gave confidence to Christopher Colum-
bus, eighteen days before the discovery of the New
World. Besides this animal, a whole society chooses
this movable habitation: in addition to the cirrhipedes
we also find the Tanais, which is not, however, con-
demned to live there always.
The macrourous decapods are more rarely found as
messmates, but still a Palemon is sometimes seen on
the body of an Actinia, according to Semper, and another
in the branchial cavity of a Pagurus. But that which
is more generally known, is the presence in the Euplec-
tella aspergillum of the palemon which lodges in this
fairy palace. It is probable that the Euplectella of the
Atlantic, recently observed near the Cape Verd Islands
by the naturalists on board the Challenger, also conceals
this crustacean in its interior. We may also allude here
to the Hypoconcha tabulosa, a crab whose carapace is too
soft to allow it to venture out undefended, and which
covers itself with the shell of a bivalve mollusc.
Among the various associations of this kind, none is
more remarkable than that of the soldier-crabs, so abun-
- dant on our coasts, and called by the names of Bernard the
Hermit and Kakerlot by the Ostend fishermen. It is
well known that these crabs are decapod crustaceans,
3
94 ANIMAL PARASITES AND MESSMATES.
very like miniature lobsters, which lodge in deserted
shells, and change their dwelling-place as they grow
larger. The young ones are content with very little
habitations.
The shells which give them shelter are such as have
been shed, which they find at the bottom of the sea, and
and in which they conceal their weakness and their
misery. These animals have an abdomen too soft to
bear the dangers which they meet with in their warfare,
and that they may be less exposed to the claws of their
numerous enemies, they take shelter in a shell which
serves at the same time both as a dwelling and a buckler.
Armed cap-a-pie, the soldier-crabs march boldly on the
the enemy, and know no danger, since they always have
a secure retreat. |
But this animal does not live alone in this asylum.
He is not so much of an anchorite as he appears to be,
for by his side an annelid usually instals himself as a
messmate, which forms with the Pagurus one of the
most terrible associations that areknown. ‘This annelid
is a long worm, like all the nereids, whose supple and
undulating body is armed along its sides with arrows,
lances, pikes, and poniards, the wounds of which are
always dangerous. It is a living panoply which glides
furtively into the enemy’s camp without giving the
alarm.
When a pagurus is on the march it resembles a nest
of pirates, who never cease their exploits till all has been
ravaged around them. ‘This shell is so innocent in its
appearance, that it introduces itself everywhere without
provoking the least suspicion. It is usually covered with
a colony of Hydractinie, and in the interior, Peltogasters,
FREE MESSMATES. 25
Lyriopes, and other crustaceans often establish them-
selves. The paguri are not messmates of an ordinary
kind, for they inhabit only a deserted shell. They are
spread over all seas. They are found in the Mediter-
ranean, the Northern Sea, on the coasts of the Pacific, of
New Zealand, and of the East Indian islands: thirty
species and even more have been inserted in the catalogue
of crustaceans.
Naturalists have given the name of Cenobite to some
pagurians inhabiting the seas of warmer latitudes; these
have an abdomen like the pagurus, antenne like the
Birgus, and like it they inhabit shells. The Cenobita
Diogenes is a species found in the Antilles.
Other pagurians, the Birgi, grow very large, and con-
ceal their abdomen no longer in a shell, but in the
crevices of the rocks, as lobsters do at the moulting time,
to protect their body while deprived of their defensive
armour. In the East Indies they remain on land, and
even climb into trees. They have so much strength in
their pincers, that Rumphius relates of one of these
crustaceans, that, while stretched on a branch of a tree,
it raised a goat by the ears.
Side by side with the pagurians which instal them-
selves in a shell with thick and completely opaque walls,
we recognize crustaceans of the order of amphinods,
the Phronime, which choose for themselveg not an aban-
doned hovel, but a veritable crystal palace, and take
possession of it without inquiring whether or no it is
inhabited. The daylight penetrates through the walls of
their dwellings, and it can scarcely be discerned in
the water whether or no their body is protected by a
covering. They usually take the dwelling of a Salpa, a
26 ANIMAL PARASITES AND MESSMATES.
Beroé, or a Pyrosoma, and from within this lodging they
cive themselves up to the pleasures of fishing.
The Phronima sedentaria which lodges with the salpa
seems to be scattered over the warm seas of both hemi-
spheres. For the honour of the species, the females
alone seek the assistance of their neighbours, without at
the same time abandoning their characteristic robe.
The sexes differ little from each other except in size,
in the abdomen, and in the antenne. Maury has de-
scribed certain amphipod crustaceans which also inhabit
the Salpe.
Another phronima described by Professor Claus, the
Phronima elongata, lives in the same manner; but instead
of occupying a living house, it generally seeks an empty
lodging, in which it establishes itself like a pagurus.
The ‘‘ Bernard the Hermit” of the Marseillaise fisher-
men, the Pyades, becomes the messmate of an anemone
which Dugés has called Actinia parasitica. According
to the observations of the learned professor at Montpelier,
the mouth of this anemone is always situated opposite to
that of the crustacean, to take advantage of the morsels
which escape from his pincers. Both of them profit
by this association; and the opening of the shell is pro-
longed by a horny expansion furnished by thé foot of the
actinia.
On the coast of England lives another soldier-crab
(Pagurus Prideauxii), which has as its principal messmate
a sea anemone called Adamsia, which Mons. Greeff found
at the island of Madeira. This pagurus is especially
remarkable for the good understanding which exists
between himself and his acolyte—he is a model Amphi-
tryon. Tieut.-Col. Stuart Wortley has watched it in its
FREE MESSMATES. . 27
private life, and thus relates the result of his observa-
tions: this animal after he has fished, never fails to offer
the best morsels to his neighbour, and often during the
day, ascertains if it is not hungry. But more especially
when he is about to change his dwelling, does he re-
double his care and his attention. He manceuvres with
all the delicacy of which he is capable, to make the
anemone change its shell; he assists it im detaching
itself, and if by chance the new dwelling is not to its
taste, it seeks another until the Adamsia is perfectly
satisfied. This association is not confined to the union
of a decapod with a nereid and an actimia; a curious
cirrhipede often establishes itself on the body of the
pagurus, and on the outside of the shell we generally
find a colony of polyps, of a rose or yellow colour, which
extend like a living carpet round this habitation. Thirty-
six years ago we have given the name of Hydractinia to
these polyps, which were till then entirely unknown to
naturalists, and which form habitually a double overcoat
for the paguri, if I may employ the expression of my
learned colleague, Mons. Ch. Desmoulins.
In the Mediterranean lives the Perella di mare of the
Italian fishermen, the Reclus marin of the Marseillaise ;
this Alcyonium ought, by its manner of life, to be
placed near the Hydractinie, and has been carefully
studied by Mons. Ch. Desmoulins. It is the Alcyoniwm
(Suberites) domuncula of Lamarck and Lamouroux.
The abdomen of these paguri is not only sheltered
in a shell, but habitually visited by isopod crustaceans,
described under the names of Athelca, Prosthetes, and
Phryxus, which have entirely lost the livery of their
order,
28 ANIMAL PARASITES AND MESSMATES.
tn the same association we also find the Liriope, a
little isopod crustacean, of which much has been said, ©
but which for a long time obstinately resisted all
attempt at observation.
This latter personage is an isopod crustacean, of
moderate size, which chooses the Peltogaster as a place
of abode, after having undergone a very curious regressive
metamorphosis. In fact, the young lyriope has at first
its little feet like other isopods, but in the adult state,
the female loses her antenne, and changes her buccal
as well as her branchial appendages, so as to assume a
different appearance. Several naturalists have already
endeavoured to give the life-history of this singular
Bopyrian. The illustrious Rathke of Konigsberg dis-
covered it; Professor Lilljeborg, of the University of
Upsal, gave the first account of it; and finally Professor
Steenstrup of Copenhagen made known its true origin.
In short, the Lyriopes are Bopyrian Isopods, living
of cirrhipedes (Sacculinidez) as real messmates, if not
as parasites; the male preserves his dignity and his
prestige, but the female strips herself of all the attri-
butes of her sex, and descends to the lowest degree of
servitude.
Faujas de Saint-Fond has mentioned a fossil hermit-
erab as found in the mountain, St. Pierre de Maestricht;
but he called by this name a crustacean of the genus
Callianassa and not a pagurus. These Callianasse are
always completely isolated in the chalk, and it is pro-
bable that they have no other domicile than the sand or
ooze at the bottom of the sea, in which they hollow
out galleries for themselves. Lobsters act in the same
manner after moulting. The Gebiz live like the Callia-
FREE MESSMATES 29
nasse, hidden in the mud. The Limnaria lignorum and
the Chelura terebrans dig out a retreat for themselves in
wood, like the Teredines.
We have just seen that the higher crustaceans, with
their well-mounted eyes, their enormous antenne, and
their formidable pincers, are not all of them the great
lords they pretend to be ; more than one of them has to
hold out its hand and to accept humbly the assistance of
its neighbours.
In the group of isopod crustaceans we find many
necessitous beings, which, too proud to ask for food, are
contented to take their place on some fish which is a
good swimmer, which they abandon as soon as their
interest demands it; if their host conducts them to
regions that do not suit them, or if they have otherwise
to complain of him, they give him up, and begin their
maritime peregrinations with a fresh colleague. They
always preserve all their fishing tackle and their sailing
gear, and the female does not change her dress any more
than the male. We have to notice that these crustaceans
often identify themselves so entirely with their host
that they seem to be a portion of him, and even to
assume his peculiar colour. This is not a sign of
servility, but a means of passing unobserved, and of
escaping from the sight of the enemy that is watching
them. Naturalists have given the name of Anilocre to -
some of these free messmates.
Any one who has remained for some time on the
coast of Brittany, especially at Concarneau, and who
does not look with indifference on the many superb
fishes which are taken every day, cannot fail to have
been struck with the presence of a rather large crusta-
30 ANIMAL PARASITES AND MESSMATES.
cean, which clings to the sides of several kinds of Labra,
especially the smaller species. This crustacean is an
Anilocrian so common that we can scarcely imagine it to
have escaped the attention of any naturalist. Neverthe-
less, no work makes mention of the regular attendance
on the Labra by the Anilocra, which bears, we know not
why, the specific name of Mediterranean. Rondelet was
probably acquainted with it, when he spoke of the fish-
lice, which do not derive their birth from these fishes,
but from the sea mud. We often see males by the side
of females on the same individual.
Some years ago a school of large cetaceans, known
under the name of Grindewhalls or Globicephale were
pursued in the Mediterranean, and those which were
captured contained in the cavity of their nostrils, isopods
closely allied to the Cirolana spinipes, if not identical
with it. Till then the isopods had only been found on
sea fishes; fresh-water fish are not, however, entirely
exempt; in fact, a species of Giga (Giga interrupta of
Martens) has just been found on the skin of a fresh-
water fish of Borneo, the Notopterus hypselonotus. This
same genus includes a species (Ciga spongiophila) which
lives in the magnificent sponge, the Huplectella. We
know also a certain number of isopods which prefer the
interior of their neighbour’s body, and instal themselves
in the cavity of the mouth, either to fish at the same
time as their host, or to seize the food on its passage ;
others are of such a cruel nature, that they make no
seruple to establish themselves in the stomach of a
peaceable white fish. Without injuring any important
organ, they penetrate in couples between the intestines,
and, concealed in this retreat, they seize by the narrow
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entrance door, which they keep half open, all the little
animals which are sufficiently bold to pass by. The
cruelty of these beings knows no bounds. To instal
themselves conveniently, they pierce the body of their
host, skilfully open his stomach, and live there as
Sybarites; their lodging is in future assured to them,
and their fate is bound, up with that of their host. Dr.
Herklots, who has unfortunately been recently lost to
science, communicated in 1869, to the Academy of the
Netherlands, a very interesting memoir on two crusta-
ceans of a new species, the Epichtys giganteus, which lives
on a fish of the Indian Archipelago, and the Ichthyoxenus
Jellinghausit, which lodges in a fresh-water fish of the
Island of Java. It is to the latter that we refer here,
and it seems that in this species we are approaching
the limits at which commensalism commences.
The Cymothoes constitute another category of very
interesting Isopods; they lodge with their female in the
cavity of a fish’s mouth. Dr. Blecker, who has so suc-
cessfully explored the Indian seas, obtained more than
twenty species of these; but unfortunately he has not
made a note of the fishes which harbour them. He has,
however, made one exception with regard to a fish from
the roadstead of Pondicherry, which is two feet long, and
is called a Bat. It is known to naturalists under the
name of Stromatea Nigra; its flesh is much esteemed,
and it carried in its mouth a Cymothoe called by Dr.
Bleeker Cymothoe Stromater. A cymothoe has also
been observed in the mouth of an Indian Chetodon.
De Kay found one in a Rhombus in the United States,
and De Saussure saw another at Cuba; and lately,
Mons. Lafont discovered one in the Bay of Arcachon, on
32 ANIMAL PARASITES AND MESSMATES.
the Boops, and on the T'rachina vipera. These cymothoes
are about fifteen millimetres in length, and often fill all
the cavity of the mouth. The most curious of all is
that which is found in the mouth of the flying-fish, a kind
of herring with elongated fins, which it uses as wings to
rise into the air, when too closely pursued in the water.
My son, when examining these fishes, in his passage
from Cape Verd to Rio de Janeiro, found in the cavity of
their mouth an enormous female, firmly wedged in the
branchial arches, with its head inclined outwards, and
the male, which was rather smaller, installed at her side.
Their dwelling thus by pairs, as well as the entire con-
formation of the animal, plainly shows that these crusta-
ceans make themselves at home, and live as true mess-
mates. Cunningham has given them the name of
Ceratothoa exoceti. A short time since, these Cymothoes
were only known on marine fishes, but it appears from
recent observations, that fresh-water fish are far from
being exempt from them. Mons. Gertsfeld has recently
noticed some on the Cyprinus lacustris of the river
Amour, and another in the Rio Cadea in Brazil, on a
Chromida. Other isopods also resort to fishes, and to
animals of their own class, but they live as true para-
sites, and change their form as soon as they have
chosen a resting-place. We shall return to this subject
again. Some which are very common on prawns, are
known under the name of Bopyrus.
An interesting division of amphipods have received
the name of Hyperine. These crustaceans generally
swim with facility, but walk with difficulty. They there-
fore usually have recourse to fishes, or even to medusa,
in order to gain support. We find on our own coasts the
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Hyperina Latreillii, lodged in the superb Lhizostoma,
which regularly appears in the later season of the year
on the coast of Ostend; and a long time since, in 1776,
QO. F. Miller gave to a species of this genus the name of
Hyperina medusarum. Mr. Alexander Agassiz once
found a Hyperina on the dise of an Aurelia. The medusa,
when extended, forms for them a balloon with its
parachute, which supports and conveys them with
greater or less rapidity. Professor Mobius has but
lately remarked the presence of Hyperina galba, Mont.,
in the Stomobrachium octocostatum, Sars, a small species
of medusa which appears in the Bay of Kiel in October
and November. ‘This naturalist supposes that these
messmates at first inhabited the Medusa aurita, and |
then migrated into this species.
Besides these, there are Gammari, which, according to
Semper, live in the Avicula meleagrina (pearl mussel),
and are perhaps the principal manufacturers of fine
pearls. The immense buccal cavity of the fishing-frog
(Lophius piscatorius) is the abode in the Mediterranean
of an Apterychta, andin the Northern Ocean of a curious
amphipod of the ordinary size of the Gammarus, which
takes a voyage without expense, and with no fear of
wanting provisions. My son discovered it at Ostend,
and proposes the name of Lophiocola to distinguish it.
The Gammari give lodging themselves to a great
quantity of parasites, which they must introduce into
the bodies of those to whom they serve as food. It
has been long known that whales have lice, to which
naturalists have given the name of Cyami. They are
found on the whales of both hemispheres, and on some
other cetaceans. It is very remarkable that they are
o4 ANIMAL PARASITES AND MESSMATES.
seen on the true whales of the north and of the temperate
regions, on the Megaptera, and on several Catodonta, and
that none are found in the Balenoptera. Myr. Dall has
just noticed some on the singular Grey Whale of Cali-
fornia. In general, we may say that each cetacean
which harbours them, has its own species. “Are they
parasites or messmates? If we are to believe Roussel
de Vauzeme, they feed on the skin itself of the whale,
the remains of which, it. is said, are found in their
stomach. According to this naturalist, the parts of the
mouth are not adapted for suction, and the stomach
contains ruminating apparatus. We think that a fresh
examination is necessary before this question can be
determined. The Cyamt seem to us to live on the
whale, as the Argult and the Caligi do on fish; and if
these living creatures derive their nourishment only from
the mucous products secreted by the skin, we may ask
whether they ought not to be classed in a separate cate-
gory, for they ought not to figure on the list of paupers.
We have found the orifice of the T’ubicinella covered with
cyami of every age, and their abundance in this place
seems to indicate that their food was not supplied to
them by the skin of their host. Mons. Ch. Lutken has
recently published a very interesting monograph on
these curious animals; according to him the Cyamus
rhytine, which was thought to proceed from a piece of
the skin of a Stellerus, appears to have been found on
the skin of a whale.
The Picnogonons, the nature as well as the kind of |
life of which has been so long time problematical,
deserve to be ranked among messmates, at least during -
their youth; in fact, after being hatched, they live on
FREE MESSMATES. 35
the Corynes, the Hydractiniz, and other polyps, while at
a later period they frequent molluscs or higher classes;
Allman mentions the case of a Phoxichilidium coccineum
lodged in a Syncoryne.
There are, perhaps, many other crustaceans which,
placed among messmates, like the Pandarus and others, |
would have a right to claim a further inquiry. It is a
fact that they are never seen except on the skin of their
host, where they are always visible, preserve their
colours entire, and never change their costume for the
undress of a parasite. The Pandari live especially on >
the Squalide. Some which are found in our seas are of ©
rare elegance of form. We must, perhaps, place among
messmates the crustacean which Siebold found in the
Adriatic, at Pola, on the belly of the worm Sabella
ventilabrum, and it is not impossible that the Stawrosoma
observed by Will on an actinia, should have its place
here rather than among the parasites.
A Rotifer without vibratory cilie, the Balatro calvus
of Claparéde, lives as an epizoon on the same annelids
which lodge the Albertia in their interior. The Dar-
winists, observes Claparéde, will not fail to remark the
presence of these Rotifers of the genus Albertia in the
interior of the animal, and of the genus Balatro on the
exterior. The parasite Balatro, like a shadow, never
quits his Mecenas, says the learned naturalist of
Geneva; who has observed it on the limicolous Oligochets
of the Seime, in the Canton of Geneva.
The Nebalia of Geoffroy is an interesting crustacean,
Abundant on the coast of Brittany. This charming
animal gives lodging habitually to a messmate which
Mons. Hesse considered as an animal allied to the
36 ANIMAL PARASITES AND MESSMATES.
Mistriobdelle, but which is only an imperfectly described
Rotator. We believe that it is the same animal to
which Professor Grube has given the name of Seison
nebalia. It appears to,assume the aspect of the Histriob-
delle, and may perhaps be adduced as an example of
mimicry.
The molluscs, whatever their name may imply, are
those which show the most independence among all the
inferior ranks of animals; not only are they contented
with the slowness of their pace and the wretchedness of
their food, but they only very rarely seek help from their
neighbours. It is not, however, uncommon to find
some living among corals, which have even been desig-
nated coralligenous molluscs. There exists a group
of Gasteropods, the Eulime, which lodge in certain
Hichinoderms, and in every respect deserve to be classed
among messmates; it was a long time before the relation
which exists between them and the animals which shelter
them had been thoroughly appreciated. Dr. Griiffe
found one species, the Hulima brevicula, on the Archaster
typicus of the Uvea Islands, in the Pacific Ocean. The
molluscs, known by the name of Stylifer, have the same
mode of life; they have been observed in the Asterie,
the Ophiure, the Comatule, and even in the Holo-
thurie; and as they inhabit the digestive cavity of
these animals, it was believed that they frequented them
as parasites. This was the opinion expressed first by
d’Orbigny, and adopted by most naturalists. Professor
Semper found some in the skin of a holothurian
(Stichopus variegatus), which he considered incapabl®
of nourishing themselves otherwise than at the expense
of their host. However this may be, these molluscs,
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ranged alternately among the Phasianellz, the Turritelle,
the Cerithia, the Pyramitdelle, the Scalariz, the Ris-
soairia, cr in a distinct family, seem to belong rather
to messmates than to parasites. We meet with Stylifers
at the entrance of the mouth (Montacuta); more
frequently they prefer, like the Fierasfers, to lodge
themselves deeply in the digestive cavity in the midst
of the débris of the prey. The Melania (M. Cambesse-
desti, Risso), which Delle Chiaie found in the Bay of
Naples, on the foot of some comatulx, belongs probably
to this group of molluscs.
Among the gasteropod molluses which are not able
to maintain themselves, we may mention another, a
curious parasite, which instals itself in one of the rays
of a star-fish, and whose presence is revealed by a swell-
ing which is not produced in the other rays. This
molluse has received the name of Stylina.
The molluses which are the most remarkable from the
point of view from which we are now considering them,
are the Entoconche; they live in Enchinoderms, and it was
thought for a while that we could see in them an example
of the transformation of one class into another. Some
years since J. Muller found in a Synapta from the Adriatic,
tubes with male and female organs, without any other
apparatus, and in these tubes appeared eges, whence this
ereat physiologist saw molluscs proceed, with a helicoid
shell, similar to that of a small natica; he gave them
the name of Entoconcha mirabilis. Professor Semper
has since discovered another species of these, which he
thas dedicated to the illustrious physiologist of Berlin,
and which he found attached to the cloacal sac of the
Holothuria edulis.
388 ANIMAL PARASITES AND MESSMATES,.
The true relation between these moliuses and the
holothurians remains to be discovered, and how the
entoconche become at last simple sexual tubes. At
present we must admit that it is the result of a retrogres-
sive development like that of the peltogasters, which, like
them, lose all the attributes of their class. They ought,
perhaps, to be placed farther on, among parasites.
Some years since, some molluscs were observed
which have compromised more or less the dignity of their
class. Graffe cites a species of the genus Cyprza, which
one would certainly not expect to find in this category ;
it lives among the Viti Islands, in the compartments of
the Milithea ochracea. We have referred to it before.
Naturalists have given the name of Melithea to a very
beautiful polyp which. forms colonies of two or three
metres in height. Mons. Steenstrup, with that perspi-
cacity which discerns the most complex phenomena, has
also described Purpure which live as messmates with the
Antipathes and the Madrepores. Quite recently, indeed,
Mr. Stimpson has observed in the port of Charleston, a
gasteropod mollusc, similar to a Planorbis (Cochliclepsis
parasitus) which lives as a messmate in the body of an
annelid (Ocates lupina).
It is not the same with a molluse called Magilus,
which naturalists considered for a long time to be the
calcareous tube of an annelid. All conchologists know
the shell of the Magili, so valued by collectors. This
gasteropod when young takes up its lodgings in the
substance of a madrepore which grows more quickly than
he, and in order not to die, stifled in this living wall, he
constructs a caleareous tube similar to the shell, of which
it appears to be the continuation, and which allows it
FREE MESSMATES. 89
to procure for itself water, air, and food. The animal,
protected by the madrepore, can do without its calcareous
mantle, and only shows the end of the tube at the outside.
It is this organ which sustains the struggle against the
exuberant growth of the polyp, since it is by means of it
that the molluse obtains nourishment. The Magilus is
hke an oyster which is living in contact with a bank
of mussels, with this difference, that the oyster almost
always succumbs, while the magilus is. always victorious
in the struggle. We might also cite as well as the
Magili, some Vermeti, certain Crepidule and Hipponices,
which struggle with the same success against those which
pilot or receive them.
As there exist parasites which only depend on others
during their youth, so there are messmates which are
completely independent when fully grown. Jacobson, of
Copenhagen, wrote, in or about 1830, a memoir to show
that the young bivalves which are found in the external
branchial processes of the Anadontex are parasites, and he
proposed for them the name oi Glochidium. Blainville
and Duméril were charged to make a report on this
memoir, which the author had sent to the Académie des
Sciences. But his opinion had not many supporters,
and it is now thoroughly known that the young anodonts
differ considerably in their early and their full-grown
state. During their stay in the branchial tubes, each
young animal carries a long cable which descends from
the middle of the foot, and serves to attach the anodont
to the. body of a fish, and yet permits it to move to
a certain distance.* iu fact the young anodonts have,
* I owe this observation to Dr. W. S. Kent, who showed me, in London,
anodonts attached in this manner to sticklebacks,
40 ANIMAL PARASITES AND MESSMATES.
not like the other acephala, vibratory wheels in order to
move themselves; they are conveyed in this manner by
their neighbours. There are also messmate acephala, as
the Modiolaria marmorata, which lodge on the mantle of
ascidians. Professor Semper found attached to the skin
of a Synapta similis, a mollusc which possesses a pecu-
liarity rare among these animals, that of carrying its
shell in the interior and not on the outside.
There are few-animals so infested with parasites as
the Ascidians in general. Not only does their surface
sometimes become a microcosm, as the name of one Medi-
terranean species indicates, but even in the substance of
their testa lodge Crenell# and other molluscs and polyps,
which choose by preference to place their dwelling there.
There are also Annelids which hollow out galleries in
their interior, Lerneans which establish themselves in
their respiratory cavity, Nematodes, Pycnogonide,
Ophiure, and many others besides. Mons. Alfred Giard
has described several Amphipods and Isopods which
establish themselves on Tunicates. One cannot say
that there is always such a complete agreement between
animals of such different kinds, for Mons. Alfred Giard
gives examples of grave disagreements which he has
seen break out, and which have caused the death of
several among them.
Another association is that of a gasteropod with one
of the acephala. In the environs of Caracas lives an
Ampullaria (Crocostoma) which lodges in the umbilicus
of its shell another mollusc, the only fluviatile species
of those countries, called the Sphaeriwm modioliforme.
We have every reason to suppose that the Sphaerium
lives on good terms with the Ampullaria, since they are
usually found associated.
FREE MESSMATES. 41
The Bryozoaria, the animal mosses, establish them-
selves on all solid bodies at the bottom of the sea, like
true mosses on stones or on trees. One species, a Mem-
branipora, is usually found on the common mussel. These
animals are of small size, group themselves in colonies
on the surface of shells and of polyparies, or even on
crustaceans, and form by their union a fine kind of lace,
the dazzling whiteness of which often comes out sharply
on the varying and glittering colour of the shell. This
is because each animal lodges in a cell which is not
larger than the head ofa pin, and all the cells of a colony
are grouped together with the symmetrical regularity of
the facade of a Gothic building.
Many Bryozoaria live in such a manner that it is’
impossible to say whether they are messmates, or have
installed themselves by chance in a hiding-place for
which they have no predilection. A charming bryo-
zoon is developed in abundance on the carapace and the
claws of the Arcturus Baffini, on the coast of Greenland,
and propagates itself with extreme rapidity. On a single
Arcturus we have found, scattered over its claws by the
side of each other, Balani, Spirorbes, Sertularie, and
vast colonies of Membranipora. One can see, merely by
this example, the great zoological riches of the polar seas.
Certain annelids off the coasts of Normandy and
Bretagne are the abodes of a bryozoary known under
the name of Pedicellina, or Loxosoma. This interesting
animal, which my fellow-labourer, Mons. Hesse, took
for a Trematode, and whose drawings had led me into
error, lives like others at liberty while young, and soon
fixes itself to a Clymenian, in order to pass as a mess-
mate the later period of its life. We have called it
42, ANIMAL PARASITES AND MESSMATES.
Cyclatella annelidicola, because of its residence in a Clyme-
nian annelid. Claparede and Keferstein have observed a
species, the Loxosoma singulare, on a capitelliian annelid,
of the genus Notomastus, at St. Vaast-la-Hogue, on the
coast of Normandy. After this, Claparede found another
species, the Loxosoma Kefersteinit, in the bay of Naples,
on an Acamarchis, a bryozoarian mollusc. Mons.
Kowalewsky has observed in the Bay of Naples the
Loxosoma Napolitanum. |
We found some years ago the Pedicelline in so
creat abundance in the oyster beds of Ostend, that the
baskets and other things floating on the water were lite-
rally covered with them. We have several times since
endeavoured to procure them again, but it was in vain
to search in the same places where they were formerly so
abundant: we have not been able to discover a single cne.
The class of worms includes not only parasites, it
contains also, as we shall see, true messmates; we find
some on crustaceans, on molluscs, on animals of their
own class, on Echinoderms, and on Polyps.
One of the most curious of these worms is the
Myzostoma, whose true nature has just been revealed by
the excellent researches of Mons. Mecznikow. These
myzostomes resemble trematode worms, but they have
symmetrical appendages, and are covered with vibratory
cilia. They live on the comatule, and run upon these
echinoderms with remarkable rapidity. They have not
hitherto been found elsewhere; they are evidently no
more parasites than the last mentioned, and their place
is among free messmates. Two great annelids are
found, the one, the Nereis bilineata, by the side of Paguri
in the sam2 shell, the other, the Nereis succinea, accord- —
FREE MESSMATES. 43
ing to Grube, in the tubes or galleries of the Teredines.
These dangerous acolytes introduce themselves furtively
into the retreat of their host; and, always on the watch,
they obtain at all times, and in every place, a certain
prey, and a hiding-place from which they can take their
share of their neighbour’s goods. Another nereis, ob-
served by Delle Chiaie, Nereis tethycola, lives in the
cavities of a sponge, the Tethya pyrifera, which is visited
by so many messmates and parasites, that it becomes a
kind of hotel, where every one establishes himself at his
ease. Risso also mentions a Lysidice erythrocephala
which lives in sponges.
In the same class is found an Amphinoma, a beauti-
ful red-blooded worm, which proudly wears a plume of
red branchie on its head, and which Fritz Muller ob-
served on the coast of Brazil, begging assistance from a
poor Lepas anatifera. Many Polynoés live upon other
~ annelids; the Harmothoé. Malmgreni on the sheath of
the Cheetopterus insignis, the Antinoe nobilis on the case
of the Terebella nebulosa. Prof. Ray Lankester has
lately communicated some observations on this subject
to the Linnean Society of London, and Dr. M’Intosh
mentions some new species leading the same kind of life
on the coast of Scotland.
Grube found at Trieste, in a star-fish (Astropecten
aurantiacus), between its rows of suckers, a Polynoé
malleata, with its stomach attached to the animal; and
Delle Chiaie has lately observed on an asteria, a Nereis
squamosa by the side of a Nereis fleruosa. Mons. Grube
thinks that the nereis of Delle Chiaie is no other than
the Polynoé malleata. Lobsters are often covered with
very small tubicular worms, which invade the whol;
44 ANIMAL PARASITES AND MESSMATES.
carapace, and which, as true messmates, give themselves
up to the caprices of their host. These are a kind of
Spirorbis, which, under the form of small spiral tubes,
instal themselves, by preference, on the limbs, the
antenne, or the claws.
Mr. A. Agassiz has seen on the coast of the United
States, a Beroé (Mnemiopsis Leidyi) which gives lodging
in its interior to worms which somewhat resemble the
Hirudinide, and which doubtless live there as mess-
mates. Mr. A. Agassiz has remarked to me another
example of commensalism. On the coast of the territory
of Washington, as far as California, is found a worm
of the genus Lepidonotus, which always lives near the
mouth of a star-fish, the Asteracanthion ochraceus of
Brandt ; sometimes as many as five are found together
on a single individual, and are placed on different parts
of the ambulacral rays. Mr. Pourtalis and Mr. Verril
have observed annelids lodged in the polypidoms of the
Stylaster.
There are few fish on which are not found Caligi,
charming crustaceans which please the eye by their -
attenuated shape and their graceful movements. On
these Caligi, which sometimes literally cover the skin of
| cod-fish coming from the north, we often find a curious
' trematode, the Udonella, which resembles one of the small
' hirudinide. Should this worm be placed among mesgs-
mates? What is the part which it plays? We are
persuaded that it is the same as that of the histriobdelle
under the tail of lobsters, that is to say, that it clears
off the eggs of caligi which do not arrive at perfection,
but perish in the course of their evolution.
Roussel de Vauzéme has mentioned another worm, a
FREE MESSMATES. 45
nematode, to which he has given the name of Odontobius,
and which lives on the palatal membranes (the whale-
bones) of the southern whale. It is evidently a mess-
mate. It can get nothing from the whalebones, but it
snaps up on their passage in the interstices of the
baleen, small animals of all kinds which swarm in these
waters. When we open the Pylidium girans, we often
find in the interior of its digestive cavity a larva, which
was once thought to be descended from it, but instead
of being allied to the Pylidium, this larva comes from a
nemertian known by the name of Alardus caudatus.
The young nemertian never abandons his host until it
approaches the period of puberty, and then all the in-
dividuals living under the same conditions emancipate
themselves at once, to pass the rest of their days free
and roving like their mother.
Worms which have less freedom, like the Distomians,
are sometimes both messmates and parasites. We
find a remarkable example of this in the Distomwm
ocreatum of the Baltic. According to the observations of
Willemoes-Suhm, this trematode passes its cercarial life
freely in the sea, and instead of encysting itself in the
body of a neighbour, it attaches itself to a copepod
crustacean, the whole of the inside of which it devours, in
order to clothe itself afterwards with the carapace of its
victim. Itis under the cover of its prey that it passes
into the herring, and completes its sexual evolution.
Mons. Ulianin has recently found another Distome
(Distomum ventricosum) which passes its cercarial life in
freedom in the bay of Sebastopol, and completes its evolu-
tion in the fishes of the Black Sea. J. Miller has long
since found Cercaria living freely in the Mediterranean.
46 ANIMAL PARASITES AND MESSMATES.
We ourselves, some years ago, while making some
researches among the Turbellaria, found among the
egos of some ordinary crabs of our coasts (Carcinus
- meznas), an interesting worm which we named Polia
involuta, but which Prof. Kolliker appears to have known
before, and designated by the name of Nemertes carcino-
philus. Itis not known whether it plays the same part
as the Histriobdellez and the Udonelle. Delle Chiaie, as
well as Prof. Frey and Prof. Leuckart, make mention of
another nemertian which inhabits the Ascidia mamillata.
Among the nemertians, we may allude to the Anoplodium
parasita, which lives in the Holothuria tubulosa, and the
Anoplodium Schneiderii, inhabiting the intestines of the
Stichopus variegatus.
According to Mr. A. Agassiz, a species of Planarian
(Planaria angulata, Mull.), lives as a free messmate
‘on the lower surface of the Limulus, and prefers to
establish itself near the base of the tail. Mons. Max
Schultze recognized last year this same messmate on a
limulus, which had died at Cologne in the large aqua-
rium, and which had been sent to him for his anatomical
studies. He showed at the congress of German natural- -
ists at Wiesbaden, in 18738, the drawing which he had
made of this animal, which he thought new to science.
We may remark in passing, that he arrived, by means of
his anatomical observations on Limuli, at the same
result as did my son by his embryogenic observations,
namely, that these supposed crustaceans are to be re-
garded as aquatic scorpions. Mr. Leidy also makes
mention of Planarian parasites (Bdellura), with a sucker
at the extremity of the body; and Mons. Giard noticed
a blue one on the body of a Botryllus.
FREE MESSMATES. 47
But of all the Turbellaria, the genus which appears to
us the most interesting is the Temnophila, which Gay first
observed on crabs at Chili, and which Professor Semper
afterwards found on the crabs of the Philippine Islands.
Gay and Phillipi found colonies of these animals on the
body, the claws, and more especially the abdomen, of
the Giglea. This messmate resembles a trematode by
its form and by its posterior sucker, but by its entire
character, and especially by its sexual organs, it belongs
to the Turbellarie. Mons. Blanchard calls it Temnophila
Chilensis. Professor Semper saw at the Philippine
Islands these Temnophile on river crabs, at five thou-
sand feet above the level of the sea.
The Cydippe densa, a charming polyp of the Gulf
of Naples, lodges in its gastro-vascular apparatus larve
of annelids, which may as well be cousidered parasites
as messmates. We owe to Panceri the first observations
on these worms, of which two genera, Alciopina and
Rhynconerulla, seem to live in the same manner in their
youth. A naturalist, whose loss is profoundly deplored
by the scientific world, Claparéde, occupied himself with
observations on these annelids during the last years of
his life. It appears that these worms are so common in
these polyps, that four have been found at once in the
same animal.
The Spoon-worm, named by Cirsted, Sipunculus con-
charum, ought doubtless to find its place here. An oligo-
chete worm, Hemidasys agaso, from the Gulf of Naples,
lives on the Nereilepas caudata, and Claparéde did not
think it unworthy of his attention. The surest means
of finding it, says this philosopher, is to look for it on
this annelid; and our much regretted fellow-labourér
4
48 ANIMAL PARASITES AND MESSMATES.
at Geneva did not abandon this messmate before he had
completely studied it. Let us remark in passing, that
Professor Grube published in 1831, at Konigsberg, a
special work on the abodes of annelids in general.
Cases of commensalism among the Echinodermata
are still more rare. ‘These animals are sufficiently
provided with organs, both with respect to their food
and their skin, not to require the assistance of their
neighbours. We cannot rank as a phenomenon of com-
mensalism, the conduct of the young Comatule, which
fasten themselves, as Mr. A. Agassiz informs me, to the
basal cirrhi of the adult echinoderms, and there form a
little colony of young Pentacrinites.
We only know one Ophiurus (Ophiocnemis obscura),
which lives as a messmate on a comatula, and con-
sequently seeks assistance from an animal of its own
rank. Another kind of. Ophiuride (Asteromorpha levis,
Lym.) fixes itself on a Gorgonella Guadelupensis of Bar-
badoes. Everything induces us to suppose that we
shall find more than one species of echinoderm, which
will take its place among these when their mode of life
has been studied with greater care. Professor Lutken
has just proved this by quite recently making known
another Ophiothela, which lives in the straits of Formosa,
and seems to be the messmate of an Isidian polyp,
known under the name of Parisis loxa. Another species
(Oph. mirabilis) from Panama, infests certain Gorgoniz
and sponges; a third is found in the Fiji Islands on the
Melitodes virgata; a fourth at the Isle of France on
Gorgonie ; and a fifth at Japan on the Mopsella Japonica.
There is also another in the Pacific Ocean, but its com-
panion is not known.
FREE MESSMATES. 49
Professor Mobius, as well as Dr. F. Martens, has
noticed a Hemieuryale pustulata on a polyp of Jamaica,
known under the name of Verrucella Guadelupensis. This
is a curious instance of mimicry.
The class of polyps includes several species which
seek for assistance from others, and are classed among
messmates. One of the most remarkable is the Gigantic
Medusa, which can extend its arms downwards to a
hundred and twenty feet, and bears the name of Cyanea
arctica; the dise is seven feet and a half in diameter,
and when the animal is on the surface of the water, the
fringes, which surround the cavity at its mouth, occa-
sionally afford lodging in the midst of them to a species
of actinia, which lives there as messmate. Sometimes
three, and even four or five, are found on a single Cyanea.
This also is an observation due to Mr. A. Agassiz,
which he has published in his interesting work, ‘‘ Sea-side
Studies.” Prof. Haeckel supposed that the Geryonix
produce Giginide by means of buds; but it appears
that the learned professor was mistaken as to the
nature of these buds; that instead of being produced
one from the other, they have, according to Steenstrup,
a completely different genealogy, being only united by
conditions of good-fellowship. They may be truly called
messmates.
Mons. Lacaze-Duthiers, who went to the coast of Africa
to study corals, met with a young polyp which requires
the assistance of another polyp in its early condition.
This animal, to which he has given the name of Gerardia
Lamarckii, lives on one of the Gorgonie, which it invades
and stifles, as the lianas strangle the tree over which
they spread themselves. But these same Gerardiz can
50 ANIMAL PARASITES AND MESSMATES.
also develop themselves on the eggs of the Plagiostoma,
and are then capable of living separately. In the sub-
stance of this polyp lives a crustacean, the nature
of which Mons. Lacaze-Duthiers has not yet made
known. |
The superb sponge, Huplectella aspergillum, the
elegant structure ‘of which cannot be sufficiently ad-
mired, is, unlike the Aleyonium of the Dromia, rooted to
the soil, but nevertheless gives shelter to three kinds of
crustaceans: Pinnotheres, Palemonide, and Isopods.
These supposed plants have been known for many years
under the Spanish name of Regadera, or the English
‘Venus’ Flower-basket;”’ they were first brought from
Japan, and afterwards from the Moluccas, and more
recently from the Philippine Islands. In almost all the
individuals which Professor Semper was able to study in
those parts, were found the same crustaceans. These
Euplectelle have just been met with to the south-west of
Cape St. Vincent, by Wyville Thomson, who has brought
up some from a depth of 1090 fathoms, while on board
the Challenger. This skilful professor has discovered
another sponge to the north-west of Scotland, at a
depth of 460 fathoms; it bears the name of Holtenia
Carpentert; and I have in my possession a fine specimen
which I owe to his generosity, and keep as a souvenir of
the delightful hospitality which he extended to me at
the Edinburgh meeting.
There are also sponges which construct a dwelling
in the abode of their neighbour. We find, among others,
a small sponge known under the name of Clione, which
establishes itself in the substance of the shell of oysters,
and hollows out galleries as the teredo does in wood.
FREE MESSMATES, 51
Mr. Albany Hancock found twelve species of Clione on
a single Tridacna. They are evidently not parasites,
and I am not sure if their place is properly among
messmates. The oyster, and more especially the Ostrea
hippopus, lodges three or four different sorts in its shell.
These Cliones possess siliceous spicules, by means of
which they hollow out galleries in the substance of
shells. Mr. Hancock has published a monograph of
this genus, in which he recognizes twenty-four species
collected from different shells, and two other species,
which he refers to the genus TJ'hoasa.
The cliones are real lodgers which lead us to the
Saaxicave, the Pholades, and the Teredines; they seek
their lodging in rocks or in wood; these lead directly
to the sea-urchins, which also hollow out lodgings in
rocks, but without penetrating deeply. Professor Allman
has just observed a very remarkable case of commen-
salism between a sponge and one of the tubularie.
The crown of the tubularia is extended at the entrance
ofthe canals of the sponge; and the association is so
complete, that the Edinburgh professor imagined that
he had before his eyes a true sponge with the arms of a
tubularia.
In the lowest ranks of the animal scale, there are
certain kinds of animalcules, which establish them-
selves on the bodies of obliging neighbours, and take
advantage of their fins in order to swim at their expense.
Thus we often find the bodies of certain crustaceans
covered with a forest of vorticelle and other infusoria.
They cause themselves to be towed like cirrhipedes, but
they do not change their toilet like them, so that it
cannot be said that they put on the livery of servitude.
52 ANIMAL PARASITES AND MESSMATES.
The kind of life led by several of these animalcule is as
yet little known.
Mons. Leydig has found in the stomach of the Hydatina
Senta a messmate which much resembles an Huglena,
and still more the Distigma tenax, Khr. -
( 53)
CHAPTER III.
FIXED MESSMATES.
THe animals- of which we have just spoken usually
_ preserve their full and entire independence; from the
time of their leaving the egg, till their complete develop-
ment, they are subject to no other outward changes than
such as belong to their class. If they sometimes renounce
their liberty, it is only for a limited time; and they all
preserve not only their peculiar appearance, but their
organs intended for fishing or for locomotion. It is not
thus with those which we are now about to consider;
they are free in their youth, but as they draw near to
puberty they make choice of a host, instal themselves
within him, and completely lose their former appear-
ance: not only do they throw aside their oars and their
pincers, but they cease sometimes to keep up any com-
munication with the outer world, and even give up the
most precious organs of animal life, not even excepting .
those of the senses; they are installed for life, and their
fate is bound up with the host which gives them shelter.
The number of these messmates is considerable.
We shall first allude to some crustaceans named
Cirrhipedes by Lamarck. The metamorphoses which
they have undergone since they left the egg have so
54 ANIMAL PARASITES AND MESSMATES.
much changed them, that Cuvier and all the zoologists
of his age placed them in the class of mollusca. The
incrustations of their skin resembled shells, which these
creatures generally carry in the substance of their
mantle.
These ambiguous creatures are far from being micro-
scopic; there are Balani which attain the size of a
walnut, and some have been found not less than ten
inches high, as the Balanus psittacus. Some years since
we saw on a piece of floating wood, found by fishermen
in the North Sea, Anatifee on the end of stalks from
six to seven feet in length. The anatife themselves
were of the usual size. These cirrhipedes belonged to
every geological period; they have already been found
in the Silurian formation, but, unlike the trilobites their
contemporaries, they pass through all the ages, and, far
from decreasing, they reign as masters at the presens
time in the two hemispheres.
It was an English naturalist, Thomson, who first
made known the true nature of these singular organ-
isms. So far were many from understanding their
affinities with the other: classes, that even after the
excellent researches of the Belfast naturalist, they
doubted their correctness, and supposed that these
animals were allied both to the mollusca and to the
articulata.
We see by this the immense progress which embryo-
logical studies have caused us to make in the apprecia-
tion of natural affinities. No one at the present time,
who has seen a cirrhipede hatched, can retain any doubt
as to the place which it ought to occupy. These crusta-
ceans, taken as a whole, lead a life in which we find
FIXED MESSMATES. 55
more than one contrast; all live as wanderers when they
first leave the egg, and they are hatched in such abun-
dance on the coast, that the water becomes literally
troubled with them. At the first period of their life,
they have a supple and elegant body, and fins admirably
divided, and the gracefulness of the postures which they
assume does not yield in beauty to those of the most
brilliant insect. After having spent some time in seek-
ing adventures, they are seized with disoust for a nomad
life; they choose a resting-place, and establish them-
selves by means of a cable which they. afterwards
abandon, and shelter themselves in an enclosed retreat
for the rest of their days. Many cirrhipedes choose the
back of a whale or the fin of a shark, and make the
passage across the Atlantic or the Pacific in less time
than the swiftest steamboats.
In many of these, recurrent development (I was about
to say degradation) sometimes proceeds so far, that their
animal nature becomes doubtful, and more than one of
them, having no longer any mouth by which to feed, are
reduced to a mere case which shelters their progeny. The
messmate very nearly takes its rank among parasites.
There are also cirrhipedes which live on different genera
of their own family; and some species which are always
found in society with other species. Some also live as
messmates with each other; some of the Sabelliphili
have one of the sexes parasitical on the other sex.
Crustaceans are usually dicecious; but because of
their manner of life, the cirrhipedes sometimes unite the
two sexes and thus render the preservation of the species
more certain. The whole family of the Abdominalia, a
name proposed by Darwin, if I am not mistaken, have
56 ANIMAL PARASITES AND MESSMATES.
the sexes separate; and the males, comparatively very
small, are attached to the body of each female. It is a
ease of polyandria which we see realized in the Scal-
pellum. Darwin made known the existence of supple-
mentary males, so small and so little developed, that
they are with difficulty discovered, and so badly are they
provided with organs that they have neither those of
motion nor a stomach to digest. We have not exhausted
the strange peculiarities of this particular group; there
are some which lve without shells and claws in the
inside of other cirrhipedes, and atrophied males which
only exist at the expense of their own females.
It is almost useless to make the remark that more
especially here there exist almost insensible gradations
of difference between parasites, messmates, and free
animals, and we shall find more than one example of
this in the crustaceans to which we now allude.
The most interesting fixed messmates are evidently
those cirrhipedes, which, under the name of Tubicinella,
Diadema, or Coronula, cover the skins of whales. They
are, like all the rest, free in their infancy, but soon they
take shelter on the back or on the head of one of these
huge cetaceans, which they never quit when they have
once chosen their abode. That which gives them great
importance is, that each whale lodges a particular
species; so that the crustacean messmate is a true flag
which indicates in some respect the nationality, and it
would not be without interest for voyagers who are
naturalists to study these living flags.
The great whale of the north, the Mysticetus, which
our northern neighbours discovered while seeking for an
eastern passage to India, a species which never leaves
FIXED MESSMATES, 57
the ice, carries no cirrhipedes. This fact was already
known to Iceland fishermen of the twelfth century. The
intrepid whalers of these regions used to distinguish a
northern whale, without ‘‘calcareous plates,” from a
southern whale with plates, that is to say, with cirrhi-
pedes. This latter whale is the celebrated species of
temperate regions, the Nord-Kaper which the Basques
used to hunt, from the sixth century, in the Channel,
and which they used afterwards to pursue even to New-
foundland. The whales of .the southern hemisphere,
like those of the Pacific Ocean, all have their own
species of cirrhipedes. We found in the museum of the
Zoological Garden at Amsterdam, a Coronula, brought
from Japan by Mr. Blomhof, known under the name of
Coronule regin®e, which, no doubt, characterizes the
whale of those latitudes. Another northern whale, the
Keporkak of the Greenlanders, very remarkable for its
long fins, which give it the name of Megaptera, is
covered very early in its life with these crustaceans, so .
much so, that the Greenlanders imagine that they are
born with them. Some even have pretended to have
seen Megapterze covered with these coronule before
their birth. Eschricht has in vain offered a reward to
him who would send him coronule still attached to the
umbilical cord; he has only received some pieces of skin
covered with hairy bulbs. Thereis no doubt that young
whales have been seen and captured while following their
mother, which were already covered by these crustaceans.
Steenstrup has indicated the presence of Platycyamus
Thompsoni on the body of the Hyperoodons, and the Xeno-
balanus globicipitis on the globiceps of the Shetland Isles.
The Cryptolepas is a new genus of Coronulide which
58 ANIMAL PARASITES AND MESSMATES.
inhabits the coast of California, on the singular mysticete
recently distinguished by the name of Ihachianectes
glaucus. The Platylepas bisexlobata has lately been
observed on one of the Sirenia, the Manatus latirostris.
The marine turtles are also invaded by these singular
animals, and their peculiar form, joined.to their habitat,
has given them the name of Chelonobia. It is not un-
common to find by the side of these Chelonobie, and
even upon them, the Tanais, Serpule, and Bryozoarie, |
forming together an animal forest on the cuirass of the
turtle. The Matamata, a turtle living in the brackish
water of Guiana, is covered with a cirrhipede more allied
to the ordinary balani than to the chelonobie. Other
living reptiles are not more exempt from cirrhipedes
than turtles; the Dichelaspis pellucida and the Concho-
derma Hunteri invade different sea-snakes. Many sharks
harbour particular kinds, among which we mention the
Alepas of the Spinax niger from the coasts of Norway.
The same Alepas has been found on the Squalus glacialis
at the same time as the Anelasma squalicola. Half a
dozen varieties of these are known, one of which inhabits
an echinoderm, another a decapod crustacean. These
kinds of alepas are so reduced when they are adult, and
are so completely despoiled of their distinctive attributes,
that it is necessary to study them with especial care in
their first dress, in order to recognize their parentage.
Other cirrhipedes establish themselves on neighbours
of their own class, and we also find crustaceans upon
other crustaceans. Aa
Fig. 8.—Gnat (culex pipiens) larva and nymph. (Blanchard.
These parasites repay by an unkind action the
assistance which they have demanded from us.
PARASITES FREE DURING THEIR WHOLE LIFE. 119
Besides the gnats, which belong to the family of
Culicide, there are also the Ceratopogon, and especially
the Simulium molestum, known in North America under
the name of Black-flies: ‘‘ the tormenting black-flies of
this country,’”’ as the Americans say. Certain Nemocera,
known by the name of Fhagio, put to flight both man
and animals.
They are very small; they get into the nostrils, and
cause animals to become blind by introducing them-
selves into their eyes. In addition to these hurtful
insects, we find others fatal to the life of animals, and
which are a real plague in certain countries.
The numerous travellers who have explored the
interior of Africa, have almost all spoken to us.of a fly
which attacks beasts of burden, and kills them in a few
hours ; this is the Tsetse (Glossina morsitans). More
than one expedition has failed on account of this
dipterous fly. It was this which obliged Green to
abandon his plan of reaching Libebe, by causing him
to lose one after another all his beasts of burden and of
draught. The horse, the ox, and the dog are more
especially attacked by this terrible fly between the 22nd
and 28th degree of longitude, and the 18th and 24th of
south latitude. Happily it does not produce any effect
upon man.
There is another fly in Mexico which is dangerous to
man ; it is known by the name of Musca hominivora, or
more correctly, Lucilia hominivora. Vercammer, a mili-
tary surgeon of the Belgian army, relates that a soldier
in Mexico had his glottis destroyed, and the sides and
the roof of his mouth rendered ragged and torn, as if a
cutting punch had been driven into those organs. This
7
120 ANIMAL PARASITES AND MESSMATES.
soldier threw up with his spittle more than two hundred
larve of this fly. We give below the figure of the larva
and of the perfect insect. He had found this man sick
in Michoacan, at a height of 1,866 metres, between
Mexico and Morelia.
Fig. 9.—Lucilia hominivora. Fig. 10.—Lucilia hominivora, larva.
My son-in-law, Dr. Vanlair, informs me that citric
acid or the juice of lemons is efficacious in destroying
these insects. Injections of this acid are thrown into
the nasal fossee.
At Brazil, in the province of Minas Geraes, thcy
give the name of Berne to a fly which attacks man and
cattle from the month of November until February. It
deposits its eggs in the loins, the arms, the legs, or even
the scrotum, without the victims perceiving it, and their
presence is first shown by a redness, then by a sensa-
tion of itching, and a swelling with the formation of pus.
Among those insects which suck the blood, is one which
is known by every one, the Breeze-fly, T’abanus bovinus.
Happily it seldom attacks any animals except oxen and
cows. We give a representation of the insect, the parts
of the mouth, and one of the antenne.
In the same order of diptera are found ordinary flies,
among which may be easily distinguished the three spe-
PARASITES FREE DURING THEIR WHOLE LIFE. 121
cies which are here represented, and which differ as much
by their external characters as by their mode of life.
Another fly also attacks horses and cattle, and occa-
sionally even man, the Asilus crabroniformis, whose
wounds sometimes draw blood. Martins, the birds of
the twilight, which fly in flocks above the houses
=o
Fig. 11.—Ox-fly. Fig. 12.—Antenna of Ox-fly.
describing circles and uttering shrill cries, are usually
infested by many vermin, among which we find a fly of
Fig. 13.—Blue Fly.
considerable size, which looks much like a spider, the
Ornithomya hirundinis. It moves about among the
122 ANIMAL PARASITES AND MESSMATES.
feathers with astonishing facility, and it is not always
confined to the same bird; it quits its host to establish
Fig. 14.—YVlesh Fly. Fig. 15.—House Fly.
itself upon another, and sometimes throws itself upon
man to suck his blood.
Some years ago these insects penetrated in the
middle of the night through the open windows into one
of the apartments of the military hospital at Louvain,
and the next morning the skin of many of the patients,
and especially the bed-linen, were covered with stains of
blood. The physicians sent me some of these insects,
not knowing whence they had come, nor whether they
had been the cause of this annoyance. During the
night, these Ornithomye had quitted their hosts to
attack the soldiers.
One of these insects, the banded Syrphus (Syrphus
balteatus), when in the larva state, seizes the rose
aphides, and sucks their blood with great eagerness.
But it is not precisely a case of parasitism, when
the wounds of soldiers are covered with larve, of which
there were many sad instances in the Crimean war.
There are flies which deposit their eggs in pus, as im
PARASITES FREE DURING THEIR WHOLE LIFE. 128
all kinds of animal matter in a state of decomposition.
It is even said that these insects, deceived by the
smell of the Arum flower, will lay their eggs on the
pistil. The name of Myasis has been given to the pre-
sence of these larve in a wound.
Every one knows that bats are often literally covered
with vermin. Among the many parasites which attack
these little animals we find, besides the acaride, a
Pteroptus of great agility, which seems, as it were, to
swim among the fur, and looks like a little spider or a
microscopic crab. There are but few bats on which we
do not find some of these, and we have sometimes seen
them in such abundance, that it was impossible to
touch a single hair without disturbing them. This
species is usually called Pteroptus vespertilionis. It is
constantly in motion, and glides among the fur like a
mole in a sandy soil.
Together with these Pteropti lives a parasite of
gigantic size, which insinuates itself among the fur with
equal dexterity, and bears the name of Nycteribia. This
has long claws lke a spider, and plunges deeply into
the fur. These Nycteribiew are found only on bats. They
are often associated on these animals with fleas and
mites. Mr. Westwood has written a monograph upon
them. Mons. Plateau, our colleague, has quite recently
described a new species in the ‘‘ Bulletins de l’Académie
de Belgique.” . ae
Among the insects justly dreaded by man, and which
follow him everywhere, is found one of the Hemiptera,
known by every one under the name of bed-bug (Cimex
lectularia). It is said that this insect was unknown in
the capital of Great Britain before the fire of London
124 ANIMAL PARASITES AND MESSMATES.
in 1666. According to some entomologists, it was in-
troduced into Europe in some wood
that came from America. It is only
necessary to make this slight refer-
ence to the Cimices ; their congeners
are, for the most part, parasites of
plants, and live on their sap.
To the same order belongs the
sincular hemipterous insect of our
ponds, the boat-fly (Notonecta). It
has some feet suited for swimming, and others for run-
ning, and it swims on its back with great rapidity. It
is a dangerous neighbour for everything that has life.
Always greedy of blood, it attacks great as well little
animals, and sucks the blood of its vietim to the last
drop, so that it must be closely watched when placed in
an aquarium.
Lice, concerning which we are about to add a few
words, are also free parasites, and belong to a different
order of insects. Their mouth is formed of a sucker
contained in a sheath, without articulations; it is
armed at the point with retractile hooks, within which
are four bristles. They have climbing feet, terminated
by pincers, with which they seize the hair of the animals
on which they live; their eggs are known by the name
of mits. We have represented in Figs. 17, 18, and 19,
the complete insect, the head, the sucker, and a claw
more highly magnified.
Lice are hatched at the end of five or six days, and
reproduce at the end of eighteen days. Leeuwenhoek
calculated that two females might become the grand-
mothers of 10,000 lice in eight weeks. They are all
Fig. 16.— Bed-bug.
PARASITES FREE DURING THEIR WHOLE LIFE. 125
parasites of the mammalia, and three species live at the
expense of man: the louse of the head, of which Swam-
merdam gave a detailed description
in his work entitled ‘“‘ Biblia Nature”;
the body-louse, which lives on the
bodies of filthy people, forms a dis-
tinct species; the third species is the
louse which occasions the disease
called *pedicularis, or Phthiriasis.
These insects were formerly much
more common than they are at the
present day. In 1825 Dr. Sichel
published a monograph concerning them; and there
appeared in the ‘Gazette Médicale” of 1871, a long
article on the history of Phthiriasis.
It is stated that several great personages have fallen
victims to its attack, but these observations date from a
period when it was thought that they could be spon-
taneously originated. It is in fact difficult to believe, as
it has seriously been stated, that lice have been seen to
issue from the bodies of men lke a spring of water from
the earth. A physician of the 16th century, named
Amatus Lusitanus, speaks of a great Portuguese noble-
man who was so covered with lice that two of his servants
were constantly occupied in collecting them and carrying
them to the sea. Andrew Murray has published a
memoir on the lice of the various races of men.
The name of helminthiasis has been proposed for
worm disease in general, and either taniaceous or
lumbricoidian helminthiasis, according to the species
which made its appearance. These parasites were con-
sidered to be formed spontaneously, and their presence
Fig. 17.—Louse of the
Head.
126 ANIMAL PARASITES AND MESSMATES.
constituted a pathological condition, two errors which
have now been recognized, and by which the science of
medicine has profited.
The Phthirius pubis is another species which has been
found only on white races, and attaches itself especially
to the hair on the pubis. Mons. Grimm has published
in the bulletins of the Academy of St. Petersburg, an
Fig. 18.—Louse of the Head; 2, 3, sucker. Fig. 19.—Louse of the Head, claw.
interesting memoir on the embryogeny of this insect ;
and, more recently, Mons. L. Landois, of Griefswald,
has completely studied its habits.
We are now about to refer to certain parasitical
insects whose name is usually associated with those
which have preceded ; they are well known by all, and
attack both men and the mammalia with no less
ferocity ; we allude to fleas, which differ from gnats in
this respect, that the male is as eager for blood as the
female, and that+ both of them, like leeches, live by
sucking it; besides, the larve of fleas live only on what
PARASITES FREE DURING THEIR WHOLE LIFE. 127
the full-grown insects bring them, whereas the larve of
gnats get their own living; the mother flea sucks for
herself first, and then divides the spoil with her larve
which as yet have no feet. For a long time it was
thought that the fleas of different animals belonged only
to a single species, and consequently that the flea of
man was not different from that of a cat or a dog.
Daniel Scholten, of Amsterdam, in 1815, showed by
his microscopical observations, that fleas differ from
each other; and in 1832, Dugés of Montpellier, investi-
gated the distinctive marks of the various species. The
observations of Scholten may be found in ‘Les
Materiaux pour une faune de la Néerlande,” by R. T.
Maitland. ,
The ordinary flea is called Pulex irritans, and espe-
cially attacks man in Europe and in North America ; it
may be called a fly without wings, and, together with its
congeners, it forms a distinct family under the name of
Pulicide. Van Helmont treated of these insects, and
gave directions for making them, just as though he were
describing a recipe for pomade. At that time, natural-
ists supposed that certain fish could be formed spontane-
ously, and that nothing but fermentation was necessary
in order to bring forth a crowd of living -creatures from
this molecular disaggregation. Fleas may, perhaps,
some day find a place in the chemist’s shop as well
as leeches. We see no reason why homeopathic
bleedings should not be resorted to, as well as home-
opathic medicines; we should certainly have more
confidence in the effects of the bites of fleas, than in
the efficacy of remedies subdivided into the millionth
part of a grain.
128 ANIMAL PARASITES AND MESSMATES.
Fleas differ much in size, according to the places
which they inhabit. Dugés, of Montpellier, gives us a
curious instance of this. He devoted himself to re-
searches on the zoological characters of this genus,
studying the four species which are the best known, the
Pulex irritans of man, Pulex canis of the dog, Pulex
musculus of the mouse, and Pulex vespertilionis of the bat.
Fleas of a brown colour, almost black, and of
enormous size, aré commonly met with on the sandy
shores of the Mediterranéan, at least, in the neighbour-
hood of Cette and Montpellier; they are more than half
as large as a common fly. These are human fleas, and
their presence on the sea-shore during the heats of
summer is due solely to the great number of bathers of
both sexes and of all classes, which lay their clothes
down there. If at some future day these insects were to
be placed in the rank of surgical species, it would be
20.—Human Flea (Pulex irritans), after Blanchard.
necessary to resort to those shores in order to procure
them; and we might suppose that, by judicious crossing,
we might soon produce races that would be of real
service; as yet, however, the therapeutic art has had
PARASITES FREE DURING THEIR WHOLE LIFE. 129
recourse only to leeches. Since we have seen these ~
insects harnessed and performing their exercises in
public, we cannot say that the future may not reserve
for us a still greater surprise.
None who saw them can have forgotten the exhibition
of learned fleas made by a young lady who had sufficient
patience to train them. Walckenaer saw them in Paris,
and examined them with the eye of an entomologist ; he
relates that thirty fleas performed their feats at evening
exhibitions, for admission to which the sum of sixty
centimes was paid; that these fleas stood on their hind
legs, armed with a pike, which was a very thin splinter
of wood; some dragged a golden chariot, others a cannon
with its carriage, and all were attached by a golden
chain on the thighs of their hind legs.
It is curious to see how Leeuwenhoek described, two
centuries ago, the history of the flea, with all its details,
the accuracy of which can scarcely be surpassed. He
observed their entire anatomy, as far as was possible
with the instruments of his time (1694), and his descrip-
tions are accompanied by excellent plates; he saw them
copulate and lay eggs, and followed their whole develop-
ment. .
The finest fleas, both as to their size and form, inhabit
the bats. Fleas are often found on horses. A colonel
of cavalry, on his return from the frontier in 1871, sent
me some of these insects, with the request that I would
examine them. He added that the horses of his
regiment were literally eaten up by them. It was the
Hematopinus tenuirosiris. There is a species peculiar
to monkeys, which Mons. Paul Gervais has described
under the generic name of Pedicinus.
130 ANIMAL PARASITES AND MESSMATES. .
At the commencement of the last century, a certain
physician attributed the cause of almost all diseases to
microscopical insects, and gave figures of ninety species
which were supposed to produce, in some cases small-
pox, in others rheumatism and gout, jaundice and whit-
lows. Almost all these figures represent imaginary
creatures. This opinion has reappeared in modern
times; how many persons have been seen to smoke
camphor in order to preserve themselves from the
invasion of animalcules. I do not speak of the apparatus
which has been contrived in order to breathe nothing
but air which has been filtered and deprived of its living
cerms.
There are some of the articulata with four pairs of
feet, a kind of microscopic spiders which require to be
noticed here; these are the numerous Acari which infest
many animals. Some of these wander on the surface of
the skin, others in galleries under the epidermis, and
many pass from one animal to another without changing
their form or mode of life. There is a considerable
number of them; no class of the animal kingdom is free
from them, neither aquatic nor terrestrial animals,
neither vertebrates nor invertebrates. These parasites
belong for the most part to the same family, and cause
by their presence a disease which was for a long time
considered to be peculiar to the skin.
An English naturalist, Mr. George Johnson, carefully
studied the parasitical and free acaride of Berwickshire.
Mons. Ehlers has written a very interesting work, with
fine illustrations, on the acaride of birds, published in
the ‘‘ Archives of Troschel.” ‘There is more than one
species which lives at the expense of man, and one of
PARASITES FRE DURING THEIR WHOLE LIFE. MG; i
them produces a disease known in every country and at
all times. under the name of
the itch; until 1830 its true
nature was still unknown. It
isnot an affection of the skin,
as was thought, but merely
the result of the presence of
these animalcules. The di-
rector of the special Hospital
for Skin Diseases at Paris was
so fully convinced that the
acaride are not the lors of Vig. 21.—Sarcoptes scabiei, or male
the itch, that he offered a senmns (or Tile: teeth 7 eee
prize to any one who could
render these insects visible. A student of medicine, a
Fig. 22,—Sarcoptes scabiei, female ; the upper surface.
132 ANIMAL PARASITES AND MESSMATES.
Corsican by birth, had happened to see these itch-insects
sought for in his own country, and was the first to prove,
in 1834, the real cause of the disease. A resident
student had given, in a thesis which he sustained at
Paris before the faculty of medicine, a drawing of a
cheese-mite instead of the wtch-insect, and this error
had caused it to be supposed that the species peculiar to
Fig. 23.—Sareoptes scabiei, male; the dorsal surface.
this disease did not exist. We give in Figures 21, 22, 23,
representations of the male and female insect, greatly
magnified.* Of course, all the treatment necessary for
the cure consists in getting rid of the animalcules and
their eggs, and in cleansing the skin and the clothes of
the patient. Petroleum oil has been judiciously pre-
scribed in order to destroy the mite, but the remedy
which seems the most efficacious is Balsam of Peru.
* Hardy, inhis Lecons sur les maladies de la peaw (Paris 1863),
devotes a special chapter to parasitical diseases, and gives the complete
history of the itch-mite.
PARASITES FREE DURING THEIR WHOLE LIFE. 13a
Most mammals have their peculiar species of acari,
and the horse has two which give rise to- different skin
affections. Since the presence of these animals con-
stitutes the disorder, it may be easily caught; man may
communicate it to domestic animals, and they may give
it to him. The itch-insect of man bears the name of
Sarcoptes scabici, and no other species than those of
Sarcoptes can be transferred from animals to man.
These animalcules have at different times been dili-
gently studied by many naturalists, and Dr. Fuestenberg
has lately published a folio volume, under the title of
“ Die Kratzmilben der Menschen und Thiere,” with large
lithographic plates, and illustrations in the text. It is
possible that the pustular disease which prevails at Sierra
Leone is originated by some peculiar acarus. Another
acarus parasitical on man, the Persian Argas, is fortu-
nately unknown in Europe. It is said to be common at
Miona, and prefers to attack strangers. Its stings pro-
duce acute pain, and travellers assure us that they may
be the cause of death. This acarus remains but a short
time on the person, and generally makes its appearance
during the night. It is called also the Miona bug.
Fischer of Waldheim has published a very interesting
memoir on this parasite. Justin Goudot has also ob-
served another Argas (A. Chinche) which torments man
in the temperate regions of Columbia.
These Arachnida, for they are articulata with four
pairs of legs, often make their appearance where we
should not expect to find a living organism, and natural-
ists, under these circumstances, have, with the best faith
possible, supposed that they had seen these mites pro-
duced spontaneously without parents. We have seen a
134 ANIMAL PARASITES AND MESSMATES.
remarkable instance of this in the Acarus marginatus of
Hermann. On the 18th Thermidor, an 2, they were
making a post mortem examination at Strasburg of a man
who had died of fracture of the skull, and when opening
the dura mater, they saw on the corpus callosum, a mite
running about which became the type of the species.
The appearance of this acarus under such conditions
made, as may be supposed, much noise at the time, but
we should not be surprised if it had been introduced
during the operation by a fly seeking to lay its eggs.
In this group is found another interesting acarus,
which is developed in man in the sebaceous crypts of the
nostrils.. The name of Simonea has been given to it,
from Dr. Simon of Berlin, who made it his especial study.
This genus leads us by its form to the Linguatule, the
structure of which has been so long doubtful. The
Simonea folliculorum belongs to the family of the Demo-
dicidex.
The dog harbours a demodex (D. Caninus) which causes
it to lose its hair. Some years ago, the sheep in Bel-
gium were attacked by one of the acaridz, the Ixodes
reduvius, which had been introduced from a neighbour-
ing country, and had multiplied with frightful rapidity.
Packard has given an account of an Ixodes bovis on the
Erethizon epixanthus, and on the Lepus Baird, and an
Argas Americana on cattle coming from Texas; this
was published in the sixth report of the United States’
Geological survey (1873).
According to the observations of Mons. Megnin, the
Tyroglyphi, the Hypopi, the Homopi, and the T'richodactyli,
are transitory forms which ought not to be preserved
as generic divisions among the acaride. We have found
PARASITES FREE DURING THEIR WHOLE LIFE. 135
on the small bat (Pipistrella) an acaride (Caris elliptica)
and a new Ixodes which we have described in a special
memoir on the parasites of the Cheiroptera. Mr. Lucas
caught an ixodes on a dog, and kept it alive long enough
distinctly to see it lay eggs which proceeded from an oyi-
duct. These eggs formed masses attached to the
abdomen of the mother.
An acarus (Dermanyssus avium) is found on birds,
and multiplies with such rapidity that it completely
exhausts those on which it has established itself. It
has been seen accidentally on man. An instance is
recorded of a woman who could not get rid of these
parasites, because she passed every day through her hen-
house in order to get to her cellar, and the frightened
fowls threw down upon her a perfect shower of acaride.
Not long ago mention was made at the Academy of
Medicine at Paris, of a sarcoptes (S. mutans), which
produces a disease among fowls, especially on the cock
and hen, and which passes from these to the horse and
other domestic animals. ‘This sarcoptes prefers to live
under the epidermis of the feet. Reptiles are not free
from its attacks, for it is often seen on lizards and
serpents. We have found a very curious one on the
skin of a gecko from the south of France.
Many insects are always covered with certain species
of acaride. Every entomologist knows that the body of
the ‘‘ watchman ” beetle always has some of these, like
little living pearls, which wander especially on the under
side of the abdomen. It is the same with a small cole-
opterous insect that is found abundantly wherever there
is any decomposing matter. Léon Dufour gave himself
up to the study of some of the parasites of insects, and
136 ANIMAL PARASITES AND MESSMATES.
mentions, among others, a species belonging to the
muscide, the Limosina lugubris, which does not measure
a line in length, and which harbours as many as fifteen
pteropti under its abdomen.
Bees, which give us their wax and their honey in
exchange for the shelter which we afford them, have a
mortal enemy, an acarus, which attaches itself to them,
not in order to gain any advantage from them, but to
cause their death. Itis not so much a parasite as an
assassin, and we may be excused from describing it. We
have found acaride on certain polyps, the Campanularie
and Sertularie of our coasts, and some years ago we
described one which is very curious, and inhabits the
southern whale, in the midst of its Cyami and Tubi-
cinelle. The anodonts of our ponds, as well as the
Fig. 24.—Hydrachna geographica.
Uniones usually have the skin of their feet and that of
their mantle encrusted with acari of every age, to which
the name of Atax ypsilophora has been given. The
species which live on the anodonts are not the same as
those which inhabit the Uniones ; and Mons. E. Bessels,
who has so fortunately returned from his voyage to the
PARASITES FREE DURING THEIR WHOLE LIFE. 137
North Pole, on board the Polaris, has seen the species
of the anodonts crossed with those of the Uniones.
There are also Arachnida which are parasitical only
while young, as the T’rombidions and certain Hydrachnz
(Fig. 24) which frequent aquatic animals. The Leptus
autumnalis, known in France, at least in some locali-
ties, by the name of Rouget, os an acarian which
throws itself upon
man, and especially
attaches itself to the "
roots of the hair: |
fortunately, it is only
found in the country
districts. The Acarus
(Cheyletus) eruditus
(Fig. 25) lives in books
and collections, as well
as on fruits and all
kinds of bodies more
or less damp, left in
dark places; it has
been studied by Van
Der Hoeven. Mons.
Leroy de Meéricourt
found in pus, which
was running from the ear of a sailor, acaride which
Mons. Robin refers to the genus Cheyletus, rather than
to that of the Acaropses.
Fig. 25.—Cheyletus eruditus.
138 ANIMAL PARASITES AND MESSMATES.
CHAPTER VIL
PARASITES FREE WHILE YOUNG.
WE have brought together in the former chapter the
animals which lve at the expense of their neighbours,
without seeking for anything except shelter. They seize
their prey as they pass, are nourished by the blood of
their neighbours, but never think of establishing them-
selves in their organs during any period of their life.
They are almost as much carnivora as parasites, and
only differ from the former.class because they spare the
life of their victims. They are unlike ordinary parasites,
since they are contented with their food alone; and their
appearance from the period of their entrance into the
world is that of free animals. Those whose history we
are now about to sketch, live in freedom like the preced-
ing during all the time that they are young; lke them,
they are completely independent during the first period
of their life; but when they have arrived at mature age,
when the endless cares entailed by their young ones come
upon them, they change their costume and accommodate.
themselves as well as they can to the new lodging which
they have chosen. There is often not the least resem-
blance between these creatures in their youth and their
adult state. All these parasites have lived a joyous life
PARASITES FREE WHILE YOUNG. 139
before choosing the host which is to serve them as a cell;
but though in many species we see both sexes shut
themselves up as in a cloister, some species are to be
found in which the female alone seeks for extraneous
aid ; which is not surprising, since she alone undertakes
all the charge of the family, and this would be beyond
her strength, and would endanger the life of her ofi-
spring, if she did not receive help and protection.
The host resembles in some respects a lying-in
hospital, especially when the female alone seeks for her-
self aresting-place and her food, which is not always the
case. We find, in fact, in a considerable number of Ler-
neans, that the microscopic male passes unperceived
upon his female, and when he renounces his bachelor
life, she feeds him with her own blood. There cannot
be a more faithful husband, since he only plays the part
of a spermatophore. We find a still more curious
example in this respect, and in which the dignity of the
male is not less compromised; we refer to the Bonelli
which live freely in the sand, and whose males establish
themselves parasitically on the sexual organs oi the
female. She herself lives by her own industry, nourishes
her husband, and alone provides for all the requirements
of maternity.
In a later part of this work, we shall mention worms
which live in freedom in damp earth, and whose direct
progeny, entirely composed of females and hermaphro-
dites, can only exist as parasites. These worms do not
resemble their mother but their grandmother, and if
their descent had‘not been traced, they would doubtless
have been taken for species entirely distinct from each
other. Thus it is not always the whole family which is
140 ANIMAL PARASITES AND MESSMATES.
modified ; the male often preserves all the attributes of
his sex and of his youth, while the female changes
entirely her appearance and her mode of motion, espe-
cially at the approach of the period when the interest of
the species prevails over that of the individual.
We can nowhere find more graceful and regular forms
during the whole of their early youth than those of
many of these parasites ; we can never see more ungrace-
ful, we might almost say more comical, attitudes than
those of the greater part of these creatures when full
srown. One might take them for some misshapen
excrescence, or some scrap of wasted flesh on the body of
their host. A certain number of insects are found which
lead this singular kind of life, but this is more especially
the case among the crustaceans, particularly the copepod
crustaceans. Among all these we find the most absurd
recurrent forms; in fact these animals instead of carrying
on their evolution, like the caterpillar which becomes a
butterfly, retrograde rather than advance, and acquire
an appearance and character which prevent us from
recognizing their origin. Many of these are at present
known, whose graceful form is so completely changed,
that without referring to the study of their embryo state,
one could not tell to what class they belong. Nothing
remains of their organs except the sexual apparatus and
a shapeless skin. These curious parasites live also on
the surface of bodies, and sometimes in the cavity of the
mouth; but in fishes they are most frequently found in
the branchial membranes. They look like natural setons,
and it is not impossible that they sometimes fulfil the
same functions. |
We will first examine some insects, then certain
-
PARASITES FREE WHILE YOUNG. 141
isopode crustaceans, an order to which the Cloportide
(wood-lice) belong, many of which require uninterrupted
assistance; then we will turn to the Lernzans, which
surpass all the rest in their many and bizarre trans-
formations.
Fig. 26.—Male Chigoe. Fig. 27—Head of Chigoe.
We have first to speak of the Chigoe, an insect, the
female of which alone demands lodging and provisions,
the male being contented, like those of the preceding
chapter, with pillaging his victim as he passes by. This
parasite of man inhabits South America, and has
received the name of Pulex penetrans, or, according to the
latest nomenclature, of Rhyncoprion penetrans. It is a
very small species, which
pierces the shoes and the
clothes with its pointed beak
(Fig. 27), and penetrates
into the substance of the
skin; the male (Fig. 26) is
contented with sucking the
blood, and then resumes
its wanderings, like the
parasites of which we have
spoken in the preceding Fig. 28. —Female Chigoe.
chapter; while the female finds for herself a hiding-
Ao ANIMAL PARASITES AND MESSMATES.
place, and becomes of such a monstrous size that the
entire insect 1s nothing more than an appendage of the
abdomen, as may be seen in the annexed figure. This
insect is well known, since it attacks man, and usually
establishes itself on his toes, but it occasionally fixes
itself in the same manner on the dog, the cat, the pig,
the horse, and the goat. It has also been seen upon the
mule. Mons. Guyon has paid much attention to it, but
we owe the last observations to Mons. Bonnet, a French
navy surgeon, who passed three years in Guiana, and
has ascertained that the chigoe fortunately does not
extend beyond the 29th degree of south latitude. Another
parasite, well known by sportsmen, is the tick. It is not
an insect like the flea, but an arachnid, a kind of acarus,
which passes through its last stages of development
under the skin of amammal. It is called Iaodes ricinus,
and Professor Pachenstecher has carefully studied its
organization. The ticks especially attack dogs, but are
also found on the roebuck, the sheep, the hedgehog, and
even on bats.
Some years ago it was propagated in an extraordinary
manner on roebucks in the woods of the Duke of Aren-
- burg, in the environs of Louvain. They are sometimes
found also on man. We know of two instances: the first
is that of alady at Antwerp, who had a small tumour on
her shoulder, which was removed, and enclosed a living
tick. Leeuwenhoek gives an instance of a woman of the
lower classes who hada tick in the middle of her stomach.
Moquin-Tandon relates that Raspail found some on the
head of a little girl four or five years old. He also gives
an instance of a young man who, returning from hunting,
found a tick under his arm; and while on the site of a
PARASITES FREE WHILE YOUNG. 143
sheep market, a servant found one morning three
attached to the skin of his breast. Delegorgue speaks
of some very small reddish ticks in Africa, which cover
the clothes by thousands, and produce distressing itch-
ing. Others are found in different parts of the globe,
and twenty-four species have been described. Several
new American Ixodes have been noticed lately by Mr.
Packard on the stag, the monax marmot, the Lepus
palustris, &e. These arachnida live at first in freedom in
the bushes, but after fecundation the female attacks the
first mammal which she finds in her way, and establishes
herself upon it; dogs become infested with it by running
in and out among the brushwood.
The Argas reflexus lives on pigeons, and is allied to
the Ixodes. KR. Buchholz has lately studied many
new acaride found on different birds.
If the forms are not so varied among the isopods as
elsewhere, many among them present nevertheless the
most extraordinary appearance, the most unexpected con-
tour. Most of the parasitic isopods instal themselves
in the thoracic cavity under the carapace of a neighbour,
and make themselves contented in the small space which
remains to them. After having disposed of their
luggage, they arrange themselves scrupulously according
to the extent of the lodging which they occupy, and,
rather than interfere with the branchie, they raise up
the walls of the cephalothorax, thus forming a sort of
tumour which betrays the presence of the intruder.
Others are found which are not contented with a natural
cavity; they raise the scale of, the skin of a fish, per-
forate or hollow out the true skin, or even pierce through
the walls of the abdomen, in order to establish themselves
8
144 ANIMAL PARASITES AND MESSMATES.
in the intestines, still keeping up a communication with
the exterior. A very common species of this class is called
Bopyrus. We often see beautiful prawns, which are
usually remarkable for their fine rose colour, exposed for
sale in shop windows. If we examine them at certain
seasons, especially in France, we perceive that the cara-
pace at the side is raised; and if we take it off with some
precaution, we discover underneath an irregular flattened
body, which fishermen take for a young sole on account
of its shape. ‘This is the female bopyrus. The many
appendages of the thorax, the division into rings, the
symmetry of the body, all have disappeared, and the
claws, the traces of which are scarcely seen, are no longer
similar on the right and left sides. The male remains
small and independent, and preserves the livery of the
order to which he belongs. On the coast of Labrador, a
bopyrus behaves in the same manner towards a Mysis.
We have found under the carapace of a pagurus a female
bopyrus full of eggs, so much flattened that it might
have been taken for a leaf accidentally introduced into
this cavity.
Fritz Muller has divided the Bopyride in the follow-
ing manner :—
1. Those which fix themselves on the appendages
or in the branchial cavity of decapods; these are the
Bopyri, Jones, Phryxi, Gyges, Athelgi, &c.
2. Those which live in the thoracic cavity of some
Brachyuri, as the Entoniscus.
38. Those which live in the cirrhipeds, lke the
Cryptoniscus, as well as the Liriopes.
4, Those which live on copepods as true parasites,
as the Microniscus (M. Fuscus).
PARASITES FREE WHILE YOUNG. 145
The Jones thoracicus, the Cepes distortus, the Gyges
branchialis, and so many others live, like the Bopyri,
in the thoracic cavity of different decapod crustaceans,
and the females throw off at the same time their organs
of sense and all their fishing and travelling apparatus.
Rathke, a learned professor of Konigsberg, was
the first to notice an isopod, known under the name
of Phryxus paguri, which lives on the stomach of a
pagurus, attached to it by its back, so that the stomach
of the parasite is turned, like that of the pagurus,
towards the partitions of the shell. The tail with the
branchial appendages is always directed towards the
orifice of the shell. The male is very small and never
leaves the female. The Athelca cladophora is another
bopyrian living on the abdominal region of a pagurus,
which always chooses shells infested by Alcyonia.
Another bopyrian, the Prosthetes cannelatus, lives on the
abdomen of an ordinary pagurus.
Mons. Bucholz has recently described a new kind
of isopod, allied to the lyriopes, which lives on the
Hemioniscus. This isopod fixes itself
to a Balanus (B. ovularis), and the
female preserves only four of her seg-
ments with their appendages: she had
fifteen, when young. Thus she throws
off nearly all her appendages which
_have become useless. The male of
this isopod, which inhabits the bay
of Christiansand, is not yet known, M#.2?—Phryxus Bath
Another parasite of this group has _ naturai size is given
been observed by Fr. Muller at Des- ** ° "4
terro, on the coast of Brazil. It bears the name of
146 ANIMAL PARASITES AND MESSMATES.
Entoniscus porcellane. The parasite which he discovered
by the side of it on the same animal, and to which he
has given the name of Lerneonscus, had perhaps in-
troduced it. We have seen examples of this kind
among insects. Among the rich materials which Pro-
fessor Semper brought back from his voyage, there was
a Porcellana, which harbours on its exterior surface a
very remarkable isopod, whose recurrent development
is no less decided than that of the peltogasters. Dr.
Kausmann has lately described these curious organisms,
to which he has given the name of Zeuwo. Another
isopod, with a no less decided recurrent development,
has received from the same naturalist the name oi
Cahira Lerneodiscoides.
We now come to an isopod which aims higher: he
doubtless considers that cray-fish and crabs walk too
slowly for him ; he therefore addresses himself to a fish,
. the Puntius maculatus, which inhabits the river Tykerang
(Bandong) in Java. This isopod is called Ichthoxenus
Jellinghausu., This isopod erustacean, living at first in
the same manner as the rest, looks out for a small
eyprinoid fish, thrusts itself like a trocar behind the
abdominal fins, through the scaly skin, and penetrates
entirely into the abdominal cavity. The male always
accompanies its female. It is remarkable that she, in
contradistinction to many others, preserves all the attri-
butes of her sex. She does not change her form more
than the other free crustaceans of her order, and only
differs from the male in size. It is well known that in
all these animals the male is always smaller than the
female. Mons. Jellinghaus, who first described this
crustacean, observed that all fishes which he caught hac,
‘ 7)
sa
eC
PARASITES FREE WHILE YOUNG. 147
without exception, the small ones as well as those which
were larger, a couple of these parasites in their stomach.
We allude to it here, but we might as well call this
Ichthoxenus a messmate as a parasite.
On the coast of Brittany, among the many Labri,
which are distinguished for their vivacity, and for the
variety of their colours, is found a small species (Labrus
Cornubiensis), on which is usually seen an isopod which
is no less curious. It is constantly clinging to the sides
of this fish, not far from the head, at the bottom of a
hollow made under the scales. Naturalists have known
this acolyte by Mons. Hesse’s works.
This Leposphilus (for this is the name which has been
given to it), though it does not prefer the scales to any
other organ, forms a lodging for itself in the sides of
this little Labrus, and takes up its abode there with its
family. We cannot assert that it has chosen this refuge
without any hope of returning, since both the sexes still
keep their organs of locomotion.
At the last congress of German naturalists at Wies-
baden, Dr. Kossmann, who has had the opportunity of
examining the rich materials brought from the Philippine
Isles by Professor Semper, gave an excellent account of
the result of his careful observations on some other
crustaceans still more remarkable, the Peltogasters of
which we have spoken before. In the course of this, he :
described an isopod with a development as completely
recurrent as that of the peltogasters, whose rank among
cirrhipeds is perfectly established.
Most of the inferior crustaceans require assistance |
from others : some might be correctly arranged as mess- )
mates, but the whole category of the Lerneans is so low ©
148 ANIMAL PARASITES AND MESSMATES.
in development that Cuvier placed them by the side of
the helminths. These creatures possess as soon as
they are born, all the attributes of their class, and wear
the dress of free crustaceans; as they approach mature
age, they choose a neighbour, instal temselves as con-
veniently as possible in one of his organs, and get rid of
all their apparatus for fishing and hunting. ‘The sexes
are usually separated, and as the female is specially
devoted to the cares of her progeny, she is the first to
give up her liberty. Sometimes the male, not content
with leaving to her all the trouble of providing for
the family, demands from her his daily food, and estab-
lishes himself like a spermatophore on her sexual organs.
It is only right to say that in this case, the male sex
is far from being the stronger, for he is often less than
the tenth or even the hundredth part of the size of the
female. At last we see the female lose her claws and her
swimming apparatus, while the male keeps his carapace
with all his appendages of the senses and of locomotion.
The difference between the two sexes is so great in some
species, that it would be impossible to imagine that a
brother and sister could assume such dissimilar forms,
unless we had watched them from the time when they
first issued from the egg. The female is a kind of
puffed-out worm, and the male resembles an atrophied
acarus. This explains why the female was known so
long before the male, whose office is only that of re-
production. Nordmann, during his residence at Odessa,
was the first to begin these researches, which have been
continued by Messrs. Metzger and Claus.
Tt is known that the Lerneans attach themselves to
their hosts by indissoluble bonds, only becoming para-
PARASITES FREE WHILE YOUNG. 149
sites after they have passed their youth in complete in-
dependence, and have all possessed the graceful forms so
characteristic of the Nauplius and the Zoé. When they
first leave the egg, they swim about in freedom, but
at length some day the female, thinking of a family,
looks out for a neighbour that can give her the assist-
ance she requires, fixes herself on his skin, and rapidly
develops till she is two or three hundred times as large
Fig. 30.—Tracheliastes of the Cyprinz. 1, larva, as it leaves the egg ; 2, larva, more
advanced; 3, adult female, attaching itself before and behind to two ovisacs (Nord-
mann).
as the male; her head, her body, and her stomach
become of a monstrous size, a part of her head is often
anchylosed in the bones of her host; the lernean
remains suspended as a sort of festoon, to which are
afterwards. joined two ovisacs filled with eggs. Fig. 30
“is a lernean of a fresh-water fish, represented at
different periods of its existence.
150 ANIMAL PARASITES AND MESSMATES.
The lerneans are the most remarkable of all para-
sites with respect to their physical degradation. They
are met with on all aquatic animals, commencing with
the cetacea, and extending to the echinodermata and
polyps; but it is especially on fishes that they are most
abundant. They live on the skin or the gills, and
sometimes establish themselves in the nostrils and on
the eye-ball. They often hang on the outside, but we
find some which hide themselves in the substance of
the skin, and have no communication with the exterior
except by a narrow orifice.
Some elegant lerneans, which resemble a living
pen, are called Penell#; their head is divided into several
branches, which plunge like roots into the tissues and
even into the bones, so that the head and all the body
remain suspended, as well as the ovisac tubes, to a long
and but slightly flexible neck. They live on the body and
the eye of certain fishes; some of great size are found in
the Indian sea, but the most remarkable are those which
have been observed on the skin of some of the cetacea.
The Penella crassicornis lives on a hyperoodon; the
Penella balenopter~ on a Balenoptera musculus among the
Loffoden Isles; the Lerneoniscus nodicornis on a dolphin ;
the great shark of the coasts of Ireland (Scimnus
glacialis) generally has a lernean on its eye. My son
brought from Rio de Janeiro some Scomberide, whose
skin is covered with penelle; and the charming fishes
so abundant on the Belgian coasts, which are called Sprot
by the fishermen of the country, often have round their
eyes strings which might be taken for marine plants, and
which are in reality only penelle. We have found
sometimes many individuals on the same fish, stretching
PARASITES FREE WHILE YOUNG. 151
from the head to the caudal region by means of their
oviferous tubes, which in certain seasons acquire a pale
green tint.
The true Lerneans, such as the Lernea branchialis, a
species that was the earliest known upon the different
Gadide, and which we have observed on the Callionyme
lyra, greatly resemble the Penelle, but their body and
their head are much twisted, and with the coils of tubes
which contain the eggs, you might take them for a ball
of thread. (Fig. 31.)
The Sphyriones called Leistera have
also a most singular form, and a new
species has been recently observed on a
fish from the Straits of Magellan. The
Conchodermagracile lives onthe branchie — Fig. 31; -hernea bran.
of the Maia squinado, the sea-spider of the gills of Morrhua
the Adriatic, and Mons. W. Salensky of
Charkow, found a copepod crustacean, the Spheronella
Leuckarti, in the egg-pouch of an Amphitoé. The latter
parasite has very peculiar characters of conformation
and embryonic evolution.
Among the molluscs, the Tunicates give lodging to
- the greater number of lerneans; in the cavity which is
before the mouth, and by which the food passes, some
are found which can scarcely be recognized, and which
remain there to smell out a feast. The Aplidiuwm of the
coasts of Belgium gives lodging to some which are very
curious, and which we have named Enterocola fulgens,
on account of their colours. The Notopterophorus estab-
lishes itself on the body of the Phallusia mamullaris,
and a certain number of these parasites are found on the
annelids. Professor Sars of Christiania, and Claparéde
152 ANIMAL PARASITES AND MESSMATES.
have carefully described them; and the latter saw on
the Spirographis Spallanzani of the bay of Naples, a
female which he called Sabelliphilus Sarsu. The genera
Selius, Sileniwm, Terebellicola, Chonephilus, Sabellacheres,
Nereicola, &c. infest all the annelids; the Hurysilenvum
truncatum lives on the Polinoé impar, the Melinnacheres
ergasiloides on the Melinna cristata.
The echinodermata and the polyps are not free from
lerneans; thus the Asterocheres Lalljeborgw fixes itself
on the Echinaster sanguinolentus, and we have found a
very beautiful species in Brittany on an Ophiurus; the
Lemippa rubra, allied to the Chondracanthi, lives upon
the Pennatula rubra, the Laura Girardie#, according to
Mons. Lacaze Duthiers, feeds on an Antipathes. A
Loemippus (Proteus) lodges in the cavity of the body of
the Lobularia digitata of Delle Chiaie; and lastly, the
Enaleyonium rubicundum is sheltered by the Alcyoniwm
digitatum.
There are certain worms which are free when young,
and only become parasites at a later period of their
evolution. We will give a few examples.
The Medina, or Guinea worm (filaria Medinensis,
dracunculus) (Fig. 32), is the terror of travellers who visit
the coast of Guinea; it is common, not only on the western
coast of Africa, but also in many other parts of this vast
continent, and has been recently found in Turkistan and
South Carolina (Mitchell). It was formerly thought that
this Filaria could introduce itself directly through the skin
as a microscopic embryo; but Mons. Fedschenko, after
some observations made on the spot, and corroborated ex-
perimentally afterwards by Leuckart, is of opinion that this
worm is transmitted by means of the Cyclops, a little
PARASITES FREE WHILE YOUNG. 153
fresh-water crustacean. Thus the parasite is received
by means of the water which is drunk; and this remark
is the more important since it will henceforth be only
necessary to make use of carefully filtered water in order:
to guard against it. At the end of six weeks, the presence
of the animal is re-
vealed by tumours, the
true nature of which
is not ascertained
at first; then some
wounds appear, caused
not directly by the
worm, but indirectly
in consequence of the
dissemination of its
egos. The Filaria at
last is so entirely atro-
phiéd that Professor
s
Sok |
ce |
ij
.
z > Fig. 32.—Young Filaria of Medina; 1,
Jacobson, after having Anterior extremity ; c. Mouth; 2, Caudal
: : extremity ; d. Anus; 3, Section of the
seen it alive on one of Body.
his patients at Copenhagen, wrote to Blainville: ‘ This
Medina worm is not really a worm, it is a sheath full of
eggs.” In fact, all the internal organs disappear and
nothing exists there except the eggs and their embryos.
The Filaria is not allied to the Mermis, as was
formerly thought; its organization is different, and its
organs become atrophied in a very different manner.
The Gordius ornatus, brought from the Philippines by
Professor Semper, has given us an opportunity, by dif-
ferent anatomical observations, to correct many errors,
especially with respect to the digestive apparatus
(Grenacher). The Filaria immitis is a species found by
154 ANIMAL PARASITES AND MESSMATESe
Mons. Krabbe in a dog which died of a disease to which
these animals are subject; it lived in the heart, and
twelve individuals, ten females and two males, were
found to be lodged there. Mons. Bap. Molin has pub-
lished a monograph on the Filarie, giving the characters
of 152 species met with in molluscs, fishes, amphibians,
reptiles, birds, and mammals: it seems evident that many
species have been confounded under the same name.
A small worm, of the size of a slender pin, but much
shorter, lives in a manner somewhat analogous to that
which we have before described. It is known under the
name of Leptodera. In order to find it, we have only to
search in the woods for the first snail that we meet with,
which is distinguished by its orange or black colour: if
we prick with a pin the fleshy foot of the mollusc, we
shall see torrents of round worms come out, wriggling
like microscopic serpents. These worms also leave
their retreat, if we cause the foot to contract by touching
it with some acid, or if we place the snail in water.
The Leptodere are especially remarkable for two fringes
which float by the side of their tail, which characteristic
suggested the name given to them by Professor Schneider.
These fringes so easily fall off, that the greater part of
those which have become free have none of these ap-
pendages. When placed in fresh or decaying animal
matter, in water or in damp earth, these worms,
agamous when in the foot of the mollusc, rapidly
become sexual and perfect. Thus the snail serves them
as a creche, and the adult worm has no.need of external
help when it has grown old.
Professor Pagenstecher found at Ostend, on the
Nicothoé of the lobster, nematodes which he arranged
PARASITES FREE WHILE YOUNG. 155
among the Leptodere. This is another instance of a
parasite on a parasite.
While speaking of these worms, I will allude to a
nematode which I observed under very singular circum-
stances. I had a considerable number of skeletons or, I
should rather say, separate bones, exposed to the sun
upon a roof to whiten; among these skeletons there
were several hyperoodons and other cetacea. All these
bones nad remained for a certain time in horse-dung in
orde> to hasten the decomposition of the soft parts. They
haa been in the open air for several weeks, and were
slowly bleaching; it had rained nearly every day.
Towards the end of the month of August, I examined
some of the vertebre, and found them quite black on the
upper part. Below, I discovered a mass of syrupy
matter, slightly yellow, like pus that has recently issued
from a wound. The sun was shining full upon the
bones at this time ; looking at them more closely, 1 saw
this pus issuing from the holes which convey nourish-
ment to the substance of the vertebre ; it seemed that
the inside of the bones was in full fermentation. Ex-
amining it with some attention, I perceived that the
whole surface was in motion; an undulatory wriggling
covered it as if a ciliated skin had been stretched above
the orifices. I took a little of this matter on the point
of a scalpel, and observed it with the microscope, and
what was my astonishment when I saw the whole mass
in motion as if under the influence of a magic wand.
When I slightly compressed it afterwards between two
slips of glass, there remained nothing before my eyes
but nematode worms of very small size wriggling over
each other: I found males by the side of their females ;
156 ANIMAL PARASITES AND MESSMATES.
in the bodies of the latter were eggs ready to be laid,
and millions of embryos of every age rolling over and
struggling among the full-grown worms. Is this a
species of worm new to science? Is it a worm which
lives in freedom here, and parasitically elsewhere ? The
first female which presents itself allows us to answer
this question. It is not a parasitical worm, at least
under this form, because each female contains only one
or two eggs. Parasites have so few chances of arriving
at their destination, that two young ones would not be
sufficient. They must have hundreds or thousands, and
then the chances are against them. This worm is
evidently a Rhabditis, but is it that which lives in the
earth, or an allied species? Future observations will
perhaps enable us soon to reply to these questions. We
do not think that these creatures could have been
brought with the bones from the Shetland Isles; they
came rather from the horse-dung, and they multiplied
beyond measure in the spongy tissue of the bones, where
they found good cheer and a convenient lodging. A worm
very nearly allied to this exists in abundance in the
dung of the cow, to which our regretted colleague, the
Abbé E. Coemans, had directed my attention, at the
time when he was studying the Pilobolus cristallinus.
That which decided us to make mention of the
nematode of the bones, is the singular history of an
ascaris of the frog, whose young ones resemble their
parents neither in size, form, or manner of life. There
is one generation which can provide for themselves, and
is composed of males and females; and another which
requires assistance, and only consists of females ; unless,
indeed, those of the male sex are hidden among the
PARASITES FREE WHILE YOUNG. rae
egos; we refer to the Ascaris nigro-venosa, the prin-
cipal characters of which have been made known by
Professor Leuckart. This Ascaris is a true parasite,
which, when it arrives at its destination, where it finds
lodging and. food, leaves the lungs to go and inhabit
another organ. ‘There is nothing surprising that certain
worms pass from the intestines to the stomach, mount
thence to the esophagus, and sometimes come out of the
mouth ; but here we have decided changes of abode in
the same animal; that which shows, besides, that it is
not a simple accident, is that the animal is of a different
sex according to the apartment which it occupies; here,
it is hermaphrodite, there it is male and female. The
Linguatule, indeed, migrate from the peritoneum of the
rabbit to the nasal fosse of the dog: but the Ascaris
nigro-venosa first lives in the lungs of the frog, then goes
to inhabit the rectum of the batrachian, or damp earth.
In the lungs it is very sriall and viviparous, and pro-
duces young ones which become stronger than their
parents. The generation which live in the lungs are
hermaphrodite, the others are diccious; that is to say,
che males and females have hermaphrodites for their
parents. We have thus a mother, a simple female or
hermaphrodite, very small, which produces, not eggs
but young ones fully formed; and instead of living, like
the mother, in the lungs, and breathing there with
greater or less facility, they go and lodge in the rectum,
and become, not like their mother, viviparous and herma-
phrodite, but oviparous and of separate sexes. They
produce in their turn a race of giants, and instead of
following the example of their father or their mother, they
all go and lodge in the lungs like their grandmother.
158 ANIMAL PARASITES AND MESSMATES.
If the hermaphrodite Ascaris mnigro-venosa alter-
nately produces individuals of separate sexes, that is to
say, if the moncecil produce dicecii, and the dicecii again
moneecii, one cannot help comparing this phenomenon to
digenetic generation. This is one of the striking dis-
coveries made at the laboratory of Giessen, under the
direction of Rud. Leuckart. Since then, Professor
Schneider, the successor of Leuckart at the University
of Giessen, has also studied these worms. Professor
Leuckart wrote thus to me a few days after this dis-
covery: ‘‘ The Ascaris nigro-venosa presents this peculiar
phenomenon, that, under the parasitical form, it pro-
duces fertile eggs without the presence of males. The
embryos which proceed from the eggs become sexual
worms at the end of twenty-four hours after they have
left the body. This fact was first observed by M.
Mecznikow, while he was working in my laboratory, and
taking part in my researches. The experiment which
produced this result was suggested and directed by
myself, in order to continue my work on the develop-
ment of the Nematodes.”
We do not know if this is the place to speak of an
animal which excited great attention some years ago, and
which was thought to prove the transformation of
animals into each other. It-is a parasite which, under
the form of a gasteropod, lives under peculiar conditions.
It is known by the name of Hntoconcha. Discovered by
J. Muller in an echinoderm of the genus Synapta, its
complete development has been vainly sought to be
discovered since that time. It is evidently a gasteropod
molluse, allied to the Natices, and lives in the interior
of the body of a Synapta, but we do not yet know all the
PARASITES FREE WHILE YOUNG. 159
phases of its evolution. It was at first thought that we
had before us an echinoderm in the act of transforma-
tion. I wrote to J. Muller immediately after the dis-
covery which he hastened to announce to me, to state
that in my opinion, this was only a new instance of para-
siticism; parasites are, however, so rare in this class of
animals, and their mode of life is so exceptional, that
one ought not to be surprised that this fact did HOt.
receive at first its true interpretation.
Professor Semper found at the Philippine Islands, in
the Holothuria edulis, another species of Entoconcha
which appears to attach itself to the anal vent of this
echinoderm. He gave it the name of Entoconcha
Mulleri. _ We have in it a new example of the relations
which certain parasites bear to their hosts, and which
are the same in both hemispheres.
The Lichnophore are infusoria, allied to the Vorti-
celle, whose form they assume; these are ‘‘ mimic
species,” or mocking forms, of the Trichodine. One
species, the Lichnophora Auerbachii lives on the
Planaria tuberculata; the other, the L. Cohnii, on the
branchial membranes of the Psyrmobranchus protensus.
The associations in the inferior ranks of animals have
functions which are of the highest importance; some to
maintain harmony and health in all that possess life,
others to sow the seeds of death throughout whole
regions. There are, in fact, associations in the ranks of
the infinitely small creatures, which sometimes have the
effect of purifying and rendering more healthful, some-
times of destroying. It is among these beings, invisible
to the naked eye, that we must seek for the cause of
some epidemic diseases. We have here an example of
160 ANIMAL PARASITES AND MESSMATES.
what certain groups of animals are able to accomplish.
The crustaceans everywhere perform the office of vul-
tures to clear the waters from dead bodies, whether large
or small, and they are in general sufficiently numerous
to perform this police duty effectually. We may say
that without their aid the waters along the coasts and
at the mouth of rivers would grow speedily corrupt and
unfit to support life. Thus it sometimes happens that
when the number of these beings is insufficient, or the
putrescible matter is in excess, we see the fish, the mol-
luses, and even the crustaceans, perish one after the
other.
The last of the parasites of this category are known
by the name of Gregarine. It appears that Goede was
the first to make observations upon them. Léon Dufour
gave them the name which they still bear. They have a
Fig. 33.—Gregarina of Nemertes Fig. 34.—Sac with Psorospermiz
Gessertensis. from the Sepia officinalis.
very simple organization, and are formed only of a cell
which contains a nucleus: they live in the intestines of
many invertebrate animals, especially in the articulata.
Let us imagine a body, long, more or less transparent,
with a smooth surface very like a spindle, which glides
about in the intestines, in the midst of the liquid matter
which it contains, without our being able to ascertain
PARASITES FREE WHILE YOUNG. 161
the mechanism by which it moves (Fig. 33.) While
young they are encysted, and bear the name of Psoro-
spermie. Fig. 34 represents one of these sacs of Pso-
rospermie from a cephalopod.
The gregarine live in their perfect form-chiefly in
insects, crustaceans, and worms. Fig. 85
represents a gregarina very common in
the libellule. The largest species inhabits
the intestines of the lobster. My son has
studied them very carefully, and pub-
lished the results in the bulletins of the
Academy of Belgium.
Schneider has described a parasite
which ought, no doubt, to be placed among
the gregarine; it lives in the testicle, as
well as in the salivary cells, of a planaria,
the Mesostomum Ehrenbergii; Schneider
represents the various phases of its de- Vj, 237jiuaunchus
velopment. In the autumn of 1871, nearly 'Y*°! ‘te Astin.
all the mesostomes perished through the presence of
these parasitical organisms: in the following year they
were rare.
Some years ago, Kélliker discovered on the spongy
bodies of molluses, certain parasites, the nature of which
appears still as enigmatical as on the first day of their
discovery. The Wurzburg professor gave them the name
of Dicyema. We have had fora long time in our portfolio
some observations upon them, and at the close of the
chapter ‘On Parasites that undergo Transformations,”
we give a representation of a Dicyema which we found in
abundance on the Sepia officinalis off the coast of Belgium.
152 ANIMAL PARASITES AND MESSMATES.
CHAPTER VIII.
PARASITES THAT ARE FREE WHEN OLD.
We are about to study in this chapter animals which
seek for assistance from others while young, and are able’
to provide for themselves completely when they have
grown old. We may compare the hosts which afford
them shelter to créches which receive none except new-
born infants. It is generally supposed that animals
known under the name of parasites are such as require
assistance from their neighbours during all the stages of
their existence.* This is amistake. There are very few
among them which are not able to provide for themselves
during some period of their development, and they then
lead an independent life. We have mentioned a certain
number of them in the preceding chapter, which only
seek for external assistance when they are old; we bring
together, on the contrary, in this chapter, those which
require help at the commencement of their life, and live
at large on their own industry when they have once made
their entry into the world. There are even some among
* The discovery of a free bothriocephalus at the bottom of a ditch
caused a great sensation in the world of naturalists some years ago. It —
was then thought that the parasite could not exist except in the body of
an animal: they could only imagine it shut up as in the cells of a gaol.
PARASITES THAT ARE FREE WHEN OLD. 163
them which are richly endowed, and one would never
imagine that they would have recourse to strangers in
order to bring up their progeny. All their young family
is usually entrusted to the care of a nurse, who lives
just long enough to bring them up; she gives them con-
venient shelter under her roof, and often bestows upon
them the last drop of her blood.
When the young one has at last abandoned her first
resting-place, she begins to think seriously of Hymen ;
she changes her dress and her mode of life, and seeks
no more extraneous assistance till she lays her eggs.
Among the animals brought up in this manner, the most
remarkable are the Ichneumons, which have always
attracted the notice of entomologists. These charming
creatures, whose shape is delicately slender, whose trans-
parent wings flutter with so much grace, have a less
stormy youth than their boldness would induce us to
suppose. As the cuckoo lays her eggs in the nest of a
strange bird, the mother ichneumon deposits hers in a
caterpillar full of health, by means of a long and
thread-like ovipositor, so that the larve as soon as they
are hatched, find themselves in a bath of blood and
viscera, which serves them for food. The different
organs palpitate under the teeth of these intruders, and
the young larva grows and increases in size till it is
hatched under the skin of its nurse: this skin is the
cradle of the ichneumon.
The young ichneumon devours its nurse piecemeal,
organ after organ; and for fear that death should super-
vene too quickly, the mother takes care to chloroform
the victim beforehand to make her last longer. The
method which many of them adopt to get rid of their
164 ANIMAL PARASITES AND MESSMATES. ~
young, reminds us forcibly of the turning-box in which
they used formerly to place children whom they wished
to be brought up by public charity ; with this difference,
that young ichneumons are not only fed and taken care
of by some good neighbour, but that her body itself
serves them as food.
It has sometimes happened that entomologists,
instead of finding beautiful butterflies produced from the
caterpillars which they had reared, have had nothing
hatched but a brood of ichneumons. Was it not natural
then for them to dream of the transformation of species,
when they saw issuing from the skin of a caterpillar,
which is usually transformed into a beautiful chrysalis,
a swarm of small winged flies which disperse with the
rapidity of lightning? These ichneumons discover with
astonishing ingenuity the caterpillar which can bring
up their young, and they often reach it with their ovi-
positor, in the midst of a fruit, or in the substance of
a branch of a tree. Every one knows the Anobium
and other little beetles which attack wood, and live in
the dark galleries which they excavate. The mother
ichneumon knows perfectly how to discover the beetle
which bores into our furniture, and winged ichneumons
have often been seen to proceed from worm-eaten wood.
It is not only caterpillars that are sought by ichneumons
for the sake of. their young; many kinds of larve o:
coleoptera and hemiptera, of aphides and weevils, are
attacked by the mother ichneumons, which plunge their
ovipositors between their articulations. These winged
corsairs well know the weak points of their cuirass.
Ichneumons are therefore decidedly parasitical at this
first period of their life. As they approach maturity, the
PARASITES THAT ARE FREE WHEN OLD. 165
time of which varies more or less according to the
species, each ichneumon takes his departure, seeks for
booty on his own account, and passes through the last
stages of his existence at full liberty in the open air.
Nothing is more beautiful than this insect in the plenitude
of its life. The species of the ichneumon are very
numerous. Mons. Wesmael has devoted a part of his
life to the study of these insects.
We often ask ourselves what can be the use of these
little creatures—what good purpose can be effected by
vermin which annoy everybody? Michelet replied to
this question when he wrote ‘The Insect.’’ ‘ Birds,”
says the brilliant historian, ‘‘ prefer to destroy those
insects which are the most injurious.” We may say the
same of those which we are now considering. The most
common caterpillar, and that which is the most dreaded
on account of its great fecundity, is precisely that which
_ 1s more eagerly sought by the greater number of ichneu-
mons. No less than thirty-five kinds of these little
assassins fall on certain species, to make them serve as
a quarry to be given to their young ones. The Bombyx
pint is one of the most dangerous and destructive insects
in our woods.. The ichneumons would seem to take into
consideration the too great fecundity of this moth, and
instead of one species, as is often the case, thirty-five
different species direct their attacks upon it. It would
be indeed difficult for the mother to withdraw her young
ones from the ovipositors of so many enemies, but there
will be always enough of them remaining to keep up the
balance in this little world; the greatness of the danger
with respect to plants will be counterbalanced by the
number of ichneumons which arrest the propagation of
1662", ANIMAL PARASITES AND MESSMATES.
the caterpillars. These insects contribute more effectually
to the destruction of caterpillars than all the means
employed by man. To arrest the Pyralis of the vine, its
cultivators encourage the little Chalcis (Chalcis minuta) ;
and it has lately been recommended to introduce the
acarus which attacks the Phylloxera, in order to lessen
the number of this new pest. Do not aphides also
prevent the too rapid development of certain plants ? and
the black species which lives on Windsor beans has
doubtless suggested to the gardener that he ought to cut
off the head of the plant when the flowers appear.
Some other hymenoptera may be mentioned: for
example, the Hvaniade, the Chalcidid#, as well as the
Tachinari#, which are remarkable for this kind of hfe.
At the moment when the mining hymenoptera introduce
into their hiding-places the msects which they have
seized, and which they destine for their young ones,
the Tachinariz introduce themselves by stealth, and lay
their eggs on these provisions. Hach kind of tachinarie
attaches itself to a particular insect. There is one essen-
tial difference between them and ichneumons, that the
females of the latter perforate the skin of their victims
with a pointed instrument, and cause their eggs to pene-
trate to the interior of the entrails; while the mother
tachine, less cruel, are contented to lay their eggs on the
surface of the skin, and leave to the larva the care of
penetrating into the interior.
In the department of the Aube, not far from Lezig-
nan, the Tithymalis (Huphorbia helioscopa) grows abun-
dantly, and the natural guest of this plant is a Sphynx.
While this sphynx is still a caterpillar, a dipterous
iachinaria takes possession of it to feed her young
PARASITES THAT ARE.FREE WHEN OLD. 167
ones. For this purpose the fly establishes itself upon
the back of the caterpillar, and mounted thus, without
the caterpillar’s suspecting the least in the world the
danger that it runs, the fly inserts her larve to the
number of ten or twelve. When she has thus deposited
these, the fly goes to seek another caterpillar, like the
cuckoo in search of a fresh nest every time that she
lays an egg.
The young flies, left to themselves, pierce the skin of
their host, and all take their place at the banquet, says
Mons. Barthelemy. .
After three moults the fly is completely developed, it
devours the interior of the larve which has nourished it,
pierces the skin, and the dead body of its host, which
might have been its tomb, becomes, on the contrary, its
cradle.
While not far off from the remains of its feast, its
own skin hardens till it becomes a veritable shell, and the
parasitical insect awakes, furnished with wings, ready
to recommence, after a minute devoted to love, the circle
‘mm which pass the unvarying phases of its evolution.
The female of the Scolia attacks the larva of the
large scarabeus (Oryctes nasicornis), which is found in
tan, and pierces it with its ovipositor at the same time
that it deposits an egg in the body of the gigantic larva.
The larva which will proceed from the egg will suck up
the fluid parts of the Oryctes while on the grass, and the
skin of its victim will serve in the spring as a cradle for
its transformation into a nymph.
Scolietes also attack the large oryctes which destroys
the cocoa-nut trees of the Seychelles Islands. “It is the
same with a large species found in Madagascar.
9
168 ANIMAL PARASITES AND MESSMATES.
There are around us, even in the midst of our cities,
insects known under the name of Scolyti, which at-
tracted much attention a few years ago. The trees by the
side of the high roads, and even those of our boulevards,
were attacked by them, and it was feared for a time that
it would not be possible to arrest this new plague, which
appeared simultaneously with the oidium of the vine
and the parasite of the potato.
The boulevards of Brussels were planted with fine
elms, and these trees were disappearing one aiter
another. The seeds of this plague were also sown in
France, in the environs of Paris. Mons. Hug. Robert
had paid attention to it, and had announced to the
Académie des Sciences a remedy to arrest the evil.
The regency of Brussels invited Mons. Hug. Robert
to eome and put in practice the means which he had
recommended to destroy the scolyti; but, if I remember
rightly, the death of the trees quickly followed that of the
scolyti. Nature,-instead of employing pitch to arrest
this plague, has simpler and more expeditious means ;
these are, to bring forward an insect equally small,
which multiplies sufficiently to keep the terrible Scolytus
under. Such is the part which has devolyed on the
Bracon iniator. It simply lays its eggs in the bodies of
the larve of the scolyti, and destroys them.
Wesmael has related a curious fact of this kind,
concerning this enemy of our plantations. These little
people can be well trusted to manage their own affairs.
Each of these hymenoptera ascertains with an admirable
instinct the place where the larve of the scolyti are to
be found, and with its long flexible ovipositor darts an
ege into the body of its victim.
PARASITES THAT ARE FREE WHEN OLD. 169
It is not only caterpillars which are assailed by
mortal enemies ; the eggs themselves are watched by some
-hymenoptera, which pierce the shell, and lay within it
their own eggs. When the larve are hatched, the yolk
and the young tissues of the legitimate uaa serve
as rations for the usurper.
In this manner, the Ophionewri live, in dae larva
state, in the egg of the Pieris brassica, the cabbage butter-
fly so abundant in our gardens; without this police
establishment they would multiply immoderately, and
our kitchen gardens would suffer still more from the
ravages of these caterpillars.
It is in vain for insects to lay their eggs in the
middle of fruits, or in the substance of a leaf or a
branch; there will be always some hymenopterous insect
which, guided by its marvellous instinct, will pierce them
with its ovipositor, and reach them without their eyen
perceiving it.
In the substance of those beautiful leaves of the
water-lily which cover our ponds in summer, we often
see a charming insect, known by the name of Agrion
virgo, or damsel dragon-fly, a name given to it on
account of its graceful attitudes and its elegant appear-
ance. We observe this insect deposit its eggs with
great prudence, fully persuaded that they are safe in
the midst of the water ; but the poor neuroptera reckons
without its host. An hymenopterous insect, named
Polynema, is there, watching every movement of the
Agrion; and as soon as the latter has laid an egg, the
Polynema darts down like a bird of prey on its victim,
pierces it, and deposits its own egg in the interior. The
egg of the wounded agrion will hatch a polynema. The
170 ANIMAL PARASITES AND MESSMATES,
cuckoo acts with less cruelty, since she is contented to
lay her eggs by the side of those which occupy the nest.
Remarkable examples of the refinement of cruelty
and of gluttony are to be found in this little animal
world. It is not enough that some among them feed
on the entrails of their young neighbours; there are
wasps which, in order to make the agony last longer,
place by the side of the eggs which they lay, chloro-
formed flies, which wait patiently for the time when
they can yield themselves up, still palpitating, to these
young tyrants. The days, the hours, perhaps even the
minutes, are scrupulously reckoned for the preparation —
of this living morsel. As the process of hatching pro-
ceeds, the repast acquires properties more and more
adapted to the age of the young wasps.
The Sphex is not less cruel. Some of the insects
which are found in South America attack, not the
young ones, but those which are grown up, and snatch
spiders from their webs as slave-hunters carry off
negroes from the wood; they garotte them, and cram
them into narrow e¢ells, after having chloroformed them
to preserve them more effectually. These spiders, retain-
ing enough life not to lose their nutritious qualities,
become the easy prey of the larve of the Sphex. The
mother of these hymenoptera takes care to deposit her
eggs, as well as the living booty, in such a manner that
the larve, at the moment of being hatched, live in abund-
ance. These young larve, white and without feet, are
dainty enough to reject any other kind of food. This
is an act of cruelty which resembles that of the
ichneumon, to which it may well be compared.
The Platygasters, another kind of hymenopterous
PARASITES THAT ARE FREE WHEN OLD. L74a
insects, show their cruelty in a different manner ; they
live in the bodies of the larve of Cecidomyz which are
lodged in the rolled leaves of the Salix, and suck the
blood of their victims.
Other insects, known by the name of Meloidex, adopt
a different plan. Their larve have been long known by
the name of bee-lice; but they had not been recognized
in the perfect state, as the larve did not resemble their
parents.
These insects undergo four different moults before
they become nymphs, and at each moult their appear-
ance is completely changed. It may be easily under-
stood that it was long before these little beings were
recognized behind their masks.
This is the manner in which they ravage our flower-
beds. While they still wear the dress of larve, they cling
to certain female hymenoptera which they know very
well; and being fully assured that the door would be
shut in their face if they presented themselves openly,
they enter, on their neighbour’s back, the galleries where
their housekeeping is carried on, and at the instant that
the female host lays an egg in a cell of honey, the young
Meloeé glides in with it, and allows itself to be shut in.
During this time it continues its metamorphosis, lying
in a lake of honey; it devours it all at its ease, caring
nothing for the provision laid up for the hymenoptera
which introduced it. It is a brigand who, having
secreted himself in the carriage of a rich neighbour,
introduces himself on his shoulders into his children’s
bed-chamber, assassinates them, and grows fat on the
provisions destined for his victims.
“The Sitaris, the Meloé, and apparently other Melo-
172 ANIMAL PARASITES AND MESSMATES.
ede, if not all of them, are, when young, parasites
of certain hymenoptera,” says Mons. Fabri, who has
watched with rare sagacity the obscure and interesting
habits of these microscopic assassins.
The Sitaris humeralis has a progressive develop-
ment at first, a recurrent one et and then again
it becomes progressive.
Aphides which are not vor full grown, and which
arrest the exuberant vegetation of certain plants, are
in their turn attacked by an insect which is by no means
lukewarm in its proceedings. A small species of cynips
(Allotria victriz) lays its eggs, like an ichneumon, in
the body of a rose aphis, and multiplies rapidly at their
expense. (Westwood).
There are certain flies which are not more delicate in
their mode of life than the preceding insects. We allude
to the distri. We give the representation of the species
which attacks the horse.
Hinder part. 36.—CEstrus of the Horse Anterior part.
Instead of making their attacks on those of their own
class, the gadflies prefer to instal themselves on mam-
mals and sometimes even on man. Fortunately their
wants are not very great; they are contented with a
PARASITES THAT ARE FREE WHEN OLD. lf
—jittle. Their presence can at most only cause some
uneasiness, or some trifling functional trouble.
The cestri are dipterous like ordinary flies; but
instead of passing their youth on some waste organic
matter, they live in the nostrils or the stomach of some
hairy animal, and undergo all their metamorphoses in
the interior of its body.
Thus they pass all their youth in a eréche; but when
they have reached the adult state, they get their own
living in freedom.
These cestri especially attack herbivorous mammals,
and the terms gastricola, cuticola, and cavicola, suffi-
ciently indicate the places which they inhabit; the first
kind lodging in the stomach, the second frequenting the
skin, and the third establishing themselves in some of
the cavities of the body.
Dr. Livingstone doubtless alludes to some kinds of
eestri when he mentioned the numerous intestinal worms
which infest animals in Southern Africa :
** All the wild animals,” says the celebrated traveller,
“are subject to intestinal worms. I have observed
bunches of a tape-like thread-worm and short worms
of enlarged sizes in the rhinoceros. The zebras and
elephants are seldom without them, and a thread-worm
may often be seen under the peritoneum of these
animals. Short red larve, which convey a stinging sen-
sation to the hand, are seen clustering round the trachea
of this animal, at the back of the throat; others are
seen in the frontal sinus of antelopes; and curious flat
Jeech-like worms are found in the stomachs of leches ”
(a new species of antelope).*
# Missionary Travels in South Africa, p. 136.
Md
174 ANIMAL PARASITES AND MESSMATHS.
A species, peculiar to the horse in Europe, usually
lives in its stomach in summer; and when its develop-
ment is complete, the winged insect follows the course of
the food, and goes out from the anus to breathe the open
air. The mother fly, excited by the sentiment of maternity,
flies round the breast of the first horse that she meets,
and lays her eggs there on some hairs which are not
beyond reach of the animal’s tongue. The horse wishing
to get rid of these foreign bodies, licks them off, and thus
they are introduced into the mouth, and from the tongue
pass to the stomach. These eggs are hatched in the
midst of the gastric juice, the larve leave them, and
the young gadflies find in the juices of the stomach the
milk which serves to nourish them. These larve pass
through their metamorphoses in the stomach, and when
the young fly has assumed its perfect form, with its
delicate wings, its sucker, and its facetted eyes, it leaves
the stomach, follows the path traced by the food, arrives
some fine day at the rectum, presents itself at the
place of exit, and takes its flight. Thus the fly can
take its journey through the intestines on a portion of
the digested food.
When she has once taken her flight she is very near
the end of her life, and after a moment of love she gives
up her place to others.
There is another gadfiy which finds a créche in the
sheep ; but instead of lodging in its stomach, it instals
itself in the nostrils, which are more easily reached. This
second species goes through its evolutions in the vestibule.
This is the species which sometimes introduces itself
into the body of man. Many instances of this have been
known, and our late colleague Spring gave a very in-
PARASITES THAT ARE FREE WHEN OLD. 175
teresting account of one of them in the bulletins of the
Belgian Academy.
A gadfly found at Cayenne is distinguished by the
name of the Macaco Worm; it belongs to the genus Cute-
rebra, and usually attacks the skin of oxen and dogs in
South America. It is accidentally found sometimes on
man. This is the Cuterebra nowialis. We here give
the representation of it.
There is also a gadfly on
the ox.
Professor Joly has devoted
himself to zoological re-
searches on Cistride in gen-
eral. Professor Schroeder
Vander Kolken, in Holland,
and Mons. Brauer, in Aus-
tria, have studied them with
great success.
The Hippoboscus is a fly
which is very greedy of
blood, and attaches itself to
horses and oxen, especially
under the tail, in the parts
where there is less hair. It Fig. 37.—Macaco Worm.
sometimes also attacks man.
The Hippoboscus lives on the horse, and an allied
species, of which a different genus has been formed, lives
on bats (Strebla vespertilionis) in South America. Mons.
Von Baér noticed hippobosci on the elan, during his
residence in Konigsberg.
Many other insects live and develop themselves at
the expense of their nearest neighbours.
176 ANIMAL PARASITES AND MESSMATES.
Travellers since Azara’s time assure us that Uruguay
contains but few oxen and horses, because a fly exists
in that country which lays its eggs in the navel of these
animals at the moment of their birth. These animals,
on the contrary, are abundant in Paraguay. In order to
increase their number in Uruguay, it would be necessary
to favour the multiplication of birds or insects which
make war on these flies, either in the larval or the sexual
state.
Diptera, known by the name of Conops, pass their
first three changes in the soft parts of drone-bees. Du-
meril had formerly suspected, from the curvature of the
abdomen, that the Conops lays its eggs in the body of
some other insect. Lachat and Victor Audouin have
given an instance of this in the ‘‘ Journal de Physique.”
Thus the Conops, in its larval state, inhabits the
abdomen of drones or other hymenoptera ; the Hchino-
myz are developed within various lepidoptera when in
the state of caterpillars or chrysalids; there are even
some which live on flesh, and prefer that which is in a
state of incipient putrefaction.
We may also speak, in this category, of animals
which seek assistance, while young, from neighbours of
whom they take advantage during their life, and utilize
them even after their death; these are insects of various
orders. They are in general more cruel than beasts of
prey, which often contend on equal terms with their
victims. Here we have an enemy which furtively intro-
duces itself into its neighbour, who is nearly sucked dry
before he suspects the danger to which he is exposed.
He harbours unawares the assassin who is about to
murder him. This is the refinement of cruelty.
PARASITES THAT ARE FREE WHEN OLD. Lee
The Melophagus of the sheep is a wingless dipterous
insect, hke the Lipoptena of the stag. We give figures
of these two curious insects.
Vig. 38.—Melophagus ovis. Fig. 39.—Lipoptena of the stag.
The Stratiome chameleon pays visits to flowers to
seek for insects, on whose blood it feeds. Its very elon-
gated larva lives in stagnant water.
We have now te mention in the following passages
parasites much less cruel in general, and which receive
with greater delicacy the hospitality which is afforded
them. We refer to some worms which pass, not their
youth, but their mature age in the body of a neighbour,
and use their host not as a creche, but as a lying-in
hospital.
Their early youth is passed in freedom, but they
soon give birth to a numerous progeny. The fate of the
male is unknown; as to the female, she introduces her-
self in a microscopic state into the body of a neighbour,
is developed there till she arrives at sexual maturity,
and then quits her retreat to go and scatter her eggs.
It appears, however, that these females are obliged to
seek assistance from insects; but before they enter this
living asylum, the male, which is not yet known, ensures
by his fecundation the preservation of the species.
178 ANIMAL PARASITES AND MESSMA'TES.
We often find in summer in puddles of water, thin
worms, which are sometimes a foot long, resembling a
violin string, and have for a long time puzzled natural-
ists. They are known by the name of Gordius, and have
lately been very carefully studied, both with reference
to their organization, to
their mode of life, and
their development. We
give here the figure of a
Gordius of the natural
size. The Mermis, like
the Gordius, passes its
youth in the body of cer-
tain insects, and leaves
its living cradle to
scatter its eggs abroad.
In this case, the embryos
themselves go to seek for
their host, and unlike the
ichneumons, they use
them with moderation. The life of the host is never
compromised, and no functional disturbance is observed,
notwithstanding the enormous size of the worm.
The Mermis is especially found after a heavy
shower; some kinds of Filaria are also more common
when it rains. Under the title of ‘‘ Notes on the Appear-
ance of Worms after a Shower of Rain,’”’ I communicated
to the Academy of Belgium some observations on these
creatures, and these observations were recorded in the
bulletins.
Some years ago they brought me one morning, after
a shower of rain, a quantity of worms, four or five inches
Fig. 40.—Gordius aquaticus, natural size.
PARASITES THAT ARE FREE WHEN OLD. 179
in length, very thin, and twisted round each other,
which had been collected in the morning, on the flower
borders of several gardens within the city. It was
thought that there had been a shower of worms in the
night.
* There was not one male worm among three hundred;
all were full of eggs, and the young ones were already
wriggling about within them.
Whence come they? said I, in my article. Have
_ they fallen from the sky completely formed? It is
evident that they have not been developed on the ground
where they have been found ; it is not less evident that
they appeared suddenly on the borders. Did they come
from within the bodies of certain insects which they have
quitted, on account of the rain which had fallen? These
worms, in fact, had completed their parasitical stage in
the bodies of their hosts, and the great drought which
had continued for many weeks prevented their resuming
their first course of existence. It was the sudden eman-
cipation of so many worms at once which had attracted
the attention of gardeners: earwigs, cockchafers, and
many other insects give them shelter during the time of
this strange gestation.
It is known, by the observations of Siebold, that the
eggs of the Mermis, laid during the winter, produce in
the following spring embryos which live in damp earth.
They immediately seek the larve of insects, perforate
their skin, and develop themselves there without be-
coming encysted. After this, they again pass through
the skin of their host, return to the damp earth, where
they change their skin, are fecundated, and lay eggs.
The larve of Mermis albicans especially resort to cater-
180 ANIMAL PARASITES AND MESSMATES.
pillars, or the larve of the coleoptera, orthoptera, or
diptera, and even to a mollusc, the Succinea amphibia.
Professor Meissner, and more especially Dr. Gre-
nacher, professor at Gottingen, have made known to us
the structure of the Gordius. The Gordius bifurcus pro-
duces embryos at the end of a month; these embryos
perforate their shell by means of their beak, become free
in the damp earth, and introduce themselves through the
skin into the perigastric cavity of certain larve. The
sexual worm again becomes free. If we may believe
Mons. Villot, who has made recent observations on the
Mermis and the Gordius, the latter alone pass through
complete metamorphoses; they assume three different
forms, and change their habitation three times. Their
first abode must be in the water, or in the larva of
a dipterous insect, as a free embryo; the second in the
larval state, in the intestines of a fish; and the third,
like the first, in a sexual state.
To judge by some specimens of gordius becuse from
India, these curious parasites exist not in Kurope only ;
_ they have been found in different parts of the world, and
they lead everywhere the same kind of life.
They have been found in Calcutta in the Hapale;
in the Philippine Islands in a Mantis, and the museum
of Hamburg possesses some from Venezuela, which came
from the body of a Blatta.
These worms, when they approach the adult and
sexual age, lose their various external organs, and are
so completely modified with respect to their organization,
that at last they are merely a case for eggs. They are
so entirely egg-cases, in which the digestive tube and
the other organs disappear in proportion as the sexual
PARASITES THAT ARE FREE WHEN OLD. 181
organs are developed, that many naturalists have taken
these worms for a simple ovisac. This has also been
the case with the Nematobothrium of the fish known
under the name of the eagle-fish; it has been taken by
an eminent naturalist for a nest of psorospermiz.
There are also worms which take refuge in plants,
and live at their expense, as if they were in an insect.
One of the most remarkable is that which attacks corn,
and produces the disease known by the name of smut,
the corn eel (Anguillulina tritici.) It is a very small
and thin cylindrical worm, which dries up completely
with the grain of corn which has nourished it, and which
can remain for an indefinite period without dying, in a
state resembling dust. Every time that it is moistened,
it resumes its activity. This return to life has been
compared to a kind of resurrection.
Mons. Davaine has studied this worm with great care ;
he has made known the different phases of its develop-
ment, and the manner in which it introduces itself into
the plant and the grain. Needham, in his ‘“ New Dis-
coveries made with the Microscope,” (1747) gives a whole
chapter to these microscopic eels.
The larve of the Anguillula scandens are dried in
the galls inhabited by the mother. As soon as these
galls fall and grow moist, the larve revive, and abandon
their cradle to live in freedom. Soon after this, they go
in search of their plant, take it by storm, and penetrate
into the tissues before the period of fecundation ; having
become sexual in the interval, these microscopic nema-
todes lay their eggs in a nest formed at the expense of
the plant.
Another species lives in the dipsacus, in which also
182 ANIMAL PARASITES AND MESSMATES.
it produces disease (Angutllulina dipsaci). It attacks
the flowers, and remains on them without signs of life
till the moment that they are moistened. The vinegar
eel is another nematode worm which has some affinity
with the preceding ones. It has been considered a
Raehitis.
There exists also a river species; but have not
different worms been confounded under this name?
Many species live in brackish water, and these are
remarkable for the presence of bristles on their heads,
and by very distinct eyes.
CHAPTER IX.
PARASITES THAT UNDERGO TRANSMIGRATIONS
AND METAMORPHOSES.
A cERTAIN number of parasites establish themselves
at first in an animal which serves as a créche, then in
a second which serves as a lying-in hospital. This
passage from one animal to another is described under
the name of transmigration. In general, the entire
creche with its nurslings passes into the lying-in
asylum. ‘The creche is always represented by an animal
which feeds on vegetable diet, which is destined for one
which is carnivorous: the lying-in asylum is represented
by the latter. The mouse is the créche which will pass
with all its clients into the cat which eats it.
If we were treating of plants, we should say that in
the first host they are developed, and in the second they
blossom. The plant, like the animal, is agamous as long
as the flower and the sexual organs have not made their
appearance.
The animal which migrates usually undergoes a com-
plete change in passing from one abode to another; it is
agamous in the first instance, that is to say, without
sex, swathed and covered with a padded cap like a nurs-
ling; in its last stage it is, on the contrary, endued with
all its sexual attributes.
184 ANIMAL PARASITES AND MESSMATES.
In the créche the parasite is on its passage from one
station to another, and that which arrives at the lying-
in asylum has reached the end of its journey and is
at home. We have proposed to give it the name of
Nostosite, as distinguished from that which only inhabits
its host for a time. We may also remark that the same
animal may give lodging to these two kinds of parasites.
It is thus that the rabbit harbours in its peritoneum
passengers which are only at home in the dog; and, inde-
pendently of these passengers (these strangers may we
say ?), it lodges in its intestines a sexual tenoid worm.
The first is a Xenosite, the second a Nostosite. The
mouse, in the same manner, gives lodging to passengers
under the name of Cysticerci, which are destined to the
cat in order to become Teenie.
We might call the rabbit or the mouse which har-
bours worms wn transitu, the stage coach; more especially
as from time to time there are some which miss it, and
are consequently lost in their peregrinations.
This stage-coach is the intermediaté host, the Zwis-
chenwirth of German helminthologists, which is always
an animal with a vegetable diet; the final host is gene-
rally a carnivore: it is by means of the vegetable
feeder, the grazing or herbivorous animal, that the
stranger parasite introduces itself.
The result of this is, that the carnivore receives into
its house, every time that it devours its prey, all the
parasitical inmates of the latter, and the walls of its
digestive canal form the soil in which are implanted all
the worms which can take root there. The tissues of
the prey are triturated and digested, but the worms
which it encloses escape the action of the gastrie juice,
TRANSMIGRATIONS AND METAMORPHOSES. 185
and are set at liberty in the stomach. The stomach of
of the carnivorous animal is a sieve through which thou-
sands of parasites are often introduced at each repast,
and fishes lodge many which often pass from one stomach
to another. Their whole life is spent in these migra-
tions; they are travellers who have their abode in railway
carriages, and never take their departure at the stations.
Each stomach is, in fact, a station, very frequently
quite filled with merchandise, which disappears with the
station itself by the next train. Happy are those who
find themselves in a carriage safely on the rails towards
its destination. Many are called but few chosen. How
many journeys some of these travellers have to take
before they find their host!
It is often very interesting to open a fish which has
made a good meal; its stomach and intestines contain,
first of all, the usual worms; the half-digested prey, in
its turn, encloses some; and it is not rare to find besides
them the parasites of those which were swallowed to-
gether with their host.
The animal is usually attacked in its youth by the
parasites which it harbours all its life. In order to know
the inhabitants of some fishes, we must examine them
shortly after they are hatched.
In the eréche the parasite occupies an organ which
is closed, and without communication with the outer
world ; it inhabits the garret of its first host; in its last
host, which represents the maternity asylum, it dwells, on
the contrary, in the largest apartments, and never ceases
to be in direct communication with the exterior. Thus,
in the first animal, it is often completely immovable
and under a form which we have named scolex; in the
186 ANIMAL PARASITES AND MESSMATES.
latter it moves freely, and has, in addition to sexual
organs, those which are proper to this condition which
we have called Proglottis. Thus these parasites undergo .
metamorphoses.
For a long time, metamorphoses seemed to be the
attributes of frogs and insects exclusively. In the class
of worms, in which they are complicated with the change
of hosts, they much surpass in reality the most bril-
liant and extravagant fictions of the poets. The
phenomena of these transmigrations were completely
unknown before our researches were made. If some
naturalists, like Abildgaard or Pallas, suspected their
existence, it was rather by accident, and the experiments
to which they devoted themselves were all unfavourable
to their suppositions.
The knowledge of these fransmigrations has at the
same time dispersed the latest illusions of the partisans
of spontaneous generation ; it was the more difficult to
explain the presence of worms in enclosed organs, since
these worms were always withovt sex. By the same
means, we have ascertained the true prophylactic treat-
ment, and thus discountenanced the numerous anthel-
minthic remedies which had often caused more serious
accidents than the parasites themselves.
When it was considered that parasites were the result
of an especial degeneration of some of the intestinal
papille, the physician would at once consider that there
was some morbid condition, and we can understand
that all his efforts would be employed against the
enemy which had arisen. Now it is known that every’
healthy animal living in freedom contains parasites |
almost as invariably as the organs which support its |
TRANSMIGRATIONS AND METAMORPHOSES. 187
life; and it is not a matter of doubt to us that parasites
often play their allotted part in the economy; their
absence as well as their presence may be the cause of
inconvenience. We should not even be astonished if the
administration of certain worms internally should be
prescribed as a remedy. Have we not known the time
when all maladies were supposed to yield to the action of
leeches, and do we not see the good effects of their appli-
cation? There are many kinds of parasites, and their
therapeutic effect may, perhaps, in future, form an
interesting subject of study. |
To speak at the present time of a verminous tempera-
ment would be scientific heresy, an anachronism’; this
shows the progress that we have made of late years.
Valenciennes was permitted to employ this language at
the Academy of Sciences in Paris not twenty years ago,
and Lamarck wrote thus in his standard work on in-
vertebrate animals, in the beginning of this century:
‘Tt is very certain that there exist in a great many
animals, and even in man, intestinal worms; some of
which are formed there, others are born and all live
there, multiplying more or less, without any of these
worms showing themselves externally, or being able to
live elsewhere.
‘‘ During. so many centuries that observations have
been made, well-ascertained species of intestinal worms
have been found nowhere else than in the bodies of ani-
mals. We are now authorized to believe that there are
innate worms, or such as are produced by spontaneous
generation, and that these are modified from time to
time; this is at present the opinion of the most en-
lightened observers.”
188 ANIMAL PARASITES AND MESSMATES.
Thus it was considered by Lamarck that parasitical
worms are only found in the bodies of animals, and are
actually produced there.
Can it be believed that such ideas were put forward
by zoologists of the highest merit? and ought we to feel
surprised that the theory of spontaneous generation was
so long taught in the physiological schools ?
A book published in 1859 was entitled, ‘‘ Hetero-
genesis, or a Treatise on Spontaneous Generation.’”’ The
author gives the clue to the origin of his errors in the
second line of his preface, in which he says: ‘*‘ When,
by meditation, it was evident to me that spontaneous
generation was one of the means employed by matter for
the reproduction of living beings.” . . . . According to
this philosopher, science is, therefore, not the general-
ization of facts, but these facts must serve to prop up
the theories or hypotheses invented in the silence of the
study. This passage of his work shows us that he was no
more able to yield to the evidence of experiments made
on worms, than to those of Pasteur on the infusoria.
It may be related to the honour of the illustrious
Baer, that, from the year 1817, during his stay at
Konigsberg, he took up arms against this hypothesis,
and never ceased to combat it, till evidence succeeded in
opening the eyes of the most obstinate.
The worms which present the most remarkable
phenomena of transformations, accompanied by metamor-
phoses, are the Distomians and Cestodes, flat worms,
which we will consider in the first place.
Trematode worms include a certain number of large
and beautiful parasites which scarcely undergo any
change, and are found only on the skin and the gills of
TRANSMIGRATIONS AND METAMORPHOSES. 189
certain fishes; these are the monogenetic trematodes,
comprising the T'ristomide and all the worms of that
sroup, which also stand higher in their organization : we
shall speak of them hereafter. The other trematodes,
which are called digenetic, ive on the most dissimilar
animals, under the most varied forms, and, like the
creater part of the cestodes, introduce themselves into the
individual who is to give them shelter, only by the assist-
ance of a host, acting as a stage-coach which serves them
as a vehicle.
The principal family is that of the Distomide, a
family par excellence cosrxopolitan;. as inconstant in
their progress as capricious in the choice of their com-
panions. Each distome resembles a small leech which
has a sucker in the centre of the belly, and as this
sucker was once considered to be perforated, the name
of Distoma was given to them.
These parasites are the more interesting to us, from
the fact that, though we are not the final resting-place of
certain species, we nevertheless find them pass through
us on their way. There are two species which occa-
sionally lodge in the liver of man without being peculiar
to him, for they properly belong to the sheep. Two
other distomes have lately been described by Dr. Bilharz,
which are fortunately only known at present in Cairo,
and which are interesting, both with respect to their ~
organization and to their manner of life.
The genealogy of the distomide is now generally well
known ; that which remains to be discovered is the
itinerary of each particular species; and in several zoo-
logical laboratories expériments are daily made with
certain species and the hosts which they are supposed
190 ANIMAL PARASITES AND MESSMATES.
to seek. These investigations have already yielded the
best results in the laboratories of Giessen and of Leipzie,
under the direction of Leuckart.
The genealogy of the distomide is as follows: the
young distome, when it leaves the egg, is wrapped in a
ciliated tunic, and, under the guise of a microscopic in-
fusorial, it abandons itself to all the vagaries of a free
and vagabond life; this is the bright period of its life.
“Tt is a youth starting, with all the steam up, without
help and without guidance, in the midst of the ocean ; if
it meets an island on its passage, that is to say, the body
of an aquatic larva or a molluse, it disémbarks, brings
forth its young, and disappears; its purpose is fulfilled.
If it find no island or continent it sinks and perishes,
for it carries no provisions with it; it has no organ which
permits it to take nourishment on its passage.” If life is
short, even in the case of a young distome, it is passed in
the midst of the water: if fortune is favourable to it, it
will at last meet with a living abode, where it will find
all that is necessary to the comfort of a parasite.
Abundance always reigns in these living oases; and
as these new colonists are really exiles, who will never
again see their native country, ciliary oars are useless to
them, and their descendants differ entirely from their
common mother.
Under the ciliated tunic of the mother appears a
daughter under the form of a bag, who is born almost
at the same time as herself, and concerning whom we
may quote here the words of Réaumur: “‘ Singular and
mysterious duality in unity; two beings, living one
within the other, which are still only a single individual.
Has nature accustomed us to such profusion? Do we
TRANSMIGRATIONS AND METAMORPHOSES. 191
ever see her retrograde thus from a more complicated
organization to one more simple ?”” That which this great
observer did not dare to believe has yet been realized,
and in many cases development is clearly recurrent.
Led by a marvellous instinct, and obeying an irre-
vocable mission, the distomide, as
well as the monostomide, and
others besides them, when they
claim an asylum from molluscs,
introduce into the living body of
their new host, not an isolated
embryo, but a young animal
already impregnated with a rich
posterity ; if she remain mistress
of the situation, this posterity
will forcibly invade the various
organs, without any consideration
whether their host may not give
way under the weight of this
sudden invasion.
Fig. 41 represents one of these
worms which proceeds from a cili-
ated embryo, and encloses by the
side of its digestive tube cercarix
in different degrees of develop-
ment. In front, we see one pro-
vided with eyes and a tail; behind,
we see others which are younger ;
among these cilated embryos,
wandering without guidance and
ii Wi Ail I
ie iy
i h YY,
a
My
Pit
iN
Fig. 41.—Monostomum verru-
cosum, Sporocyst with Cer-
earie. In frontis the mouth,
in the middle the digestive
eanal, and around the diges-
tive canal are young ones,
under the form of Cercariz
in process of development.
without a compass in the midst of their ocean, but few
will reach the land, or, in other words, will find the
10
192 ANIMAL PARASITES AND MESSMATES.
port where their progeny may prosper. — This first em-
bryonic state is that in which there are the greatest
perils. When stripped of their swimming tunic, these
young distomes have the form of a bag, which for a long
time was called a sporocyst. From these sporocysts we
see hundreds and thousands of young ones proceed,
resembling in no respect the mother, which has brought
them into the world. These, in their turn, will resume
a free and independent life. They are colonists whom
the distome has left on a foreign land. This simple
multiplication is often not sufficient for the preservation
of the species ; the first sporocyst produces other similar
sporocysts, and these bring into the world a rich pro-
geny of tadpoles, which after a certain metamorphosis
will become sexual distomes. These tadpoles are often
well armed, and devour occasionally even the last scrap
of flesh belonging to their host. They have long been
known under the name of Cercarizw, which was given to
them at a time when their genealogy was unknown.
They are not very unlike the tadpoles of the frog (Fig. 45).
The mother was only a bag with cilix, and sometimes
with eyes. The tadpole has a distinct body, with a
movable deciduous tail; and after this falls off they
have sexual organs.
The cercariz often abandon their first host in which
they have been developed, and live at liberty in the
water while waiting for their final host. They are taken
sometimes in the open sea. In 1849, J. Muller wrote to
me from Marseilles that he had just discovered cercariz
and distomes living at liberty in the Mediterranean.
Since then this illustrious naturalist has observed them
again at Trieste, while pursuing his studies on the
TRANSMIGRATIONS AND METAMORPHOSES, 193
Echinodermata, and has had the kindness to send me
his original drawings of these singular parasites.
We have found both at Marseilles and at Trieste,
says J. Muller, a new cercaria with a pinnate tail, and
two black ocular points; its body is from one-tenth to
one-sixth of a line in length, not including the tail, which
is twice or two-and-a-half times as long. There is a pro-
tuberance just in front of the middle of the body. At
each side of the tail there are from twelve to twenty
pencils of soft bristles placed on little prominences in a
transverse series of six tufts, not regularly opposed to each
other. In one specimen, the tail, from its point of
insertion to the posterior quarter, is provided with these
bundles of bristles; and in another they are wanting
entirely in the anterior half, but exist, on the contrary,
on the hinder half. In a third, the bristles have par-
tially disappeared, and are reduced to six bundles at the
extremity of the tail. This tail presents traces, more or
less distinct, of transverse rings. J. Muller has often
seen that the distome, which proceeds from this cercaria,
swims freely in the sea, and after having got rid of its
tail, could be easily recognized by the two black marks
which were then more diffused.
This cercaria described by J. Muller recalls to us that
which was noticed by Nitzsch on fresh-water shells
(Cercaria major) with an annulate and pinnated tail.
Claparéde also took at Saint-Vaast, cercariz the host
of which he did not know. This naturalist supposed
that this worm could migrate at will. He found there
the same cercaria (C. Haimeana) on Sarsizv and Oceanie,
but always sexless.
The Cercaria setifera of J. Muller has been found
194 ANIMAL PARASITES AND MESSMATES.
free and attached to the lower surface of some meduse.
It exists occasionally in considerable numbers on the
internal surface of some Acalephe of the ocean and of
the Mediterranean. Claparéde has also observed another
free cercaria which bears the name of Pachycerca.
Some of the cercarie are very tenacious of life; we
have kept some alive in fresh water during a whole week
in the month of November, and on the last day they
were still active (Cercaria armata). We sometimes find
the cercarian age passed over, and the young distomes
appear abundantly without tails in the sporocyst. We
have seen an example of this in the Buccinum undatum
of our coasts. This latter generation assumes in every
case a very different form from that which preceded it.
Lodged and nourished without expense in the succu-
lent parenchyma of their victim, the cercarie grow
rapidly, and as soon as their caudal oar is developed,
they tear asunder the membrane which encloses them,
and abandon their host in order to live freely as tad-
poles. Some fine day, tired of their nomadic life, they
choose another host, get rid of their tail, fold themselves
up in a winding-sheet, like a chrysalis about to become
a butterfly, and concealed in a sac, which is designated
by the name of cyst, they wait patiently for days,
weeks, or years till their host is swallowed by the
creature intended to lodge them. The cyst is set free in
the stomach of the latter host, its envelopes are dis-
solved in the juice secreted by its enclosing membrane,
and with its whole establishment the worm recovers its
liberty in this new abode.
The encysted cercarie pass thus with arms and bag-
gage into the stomach of a new host. Their envelopes,
TRANSMIGRATIONS AND METAMORPHOSES. 195
not to say their swaddling-clothes, are torn to pieces by
the gastric juice, and at the end of their stage they go
and lodge in larger apartments, more appropriate to
their new wants. The time of their celibacy is passed,
and a numerous progeny, under the form of eggs, is
prepared. In this condition they fulfil their last
mission; and if their mother, the sporocyst, knew only
the joys of agamous maternity, the cercaria which has
just become a distome appreciates all the sweetness of
sexual maternity.
The distome thus reaches the termination of its voy-
age and of its evolutions; it lays its eggs in the midst
of the feces of its host, and millions of animalcule
watch for the new brood, while others wait for the visit
of the ciliated generations. The daughter distome thus
differs completely from her mother sporocyst, but she
resembles her grandmother who has lived in the same
manner as herself. Thus we have animals free and
vagabond when they leave the egg, and which swim
vigorously like infusoria without depending on others. -
But the end of their life approaches, they strip them-
selves of their ciliated mantle, and being again closely
swathed up before they die, they seek the hospitality of
a molluse and give birth to their numerous progeny.
We have therefore animals whose little ones in
swaddling clothes live at first at liberty, and seek for
assistance when the moment for thinking of a family
approaches. ‘The descendants lead, like their parents, a
wandering life; and as their mother threw off her ciliated
cloak, so they abandon their oar-like tail, to think in
their turn of family cares.
To sum up all, there are in the life circle of a dis-
196 ANIMAL PARASITES AND MESSMATES.
tomian two distinct forms, which begin and end in the
same manner, the first putting forth a progeny by means
of buds, the second by eggs. There is alternation of
form, on account of the double multiplication (digenesis)
and migration through several individuals. In other
words, the young distome, before it reaches its destina-
tion, must change its train many times, and it wears in
each carriage a different costume. We can easily under-
stand how difficult it is to recognize this travelling dis-
tomian, as it changes continually its railway-train and
its dress, and what sagacity must have been employed
by naturalists in order not to lose its track.
We may give more than one description of the dis-
tomian embryo as it leaves its sporocyst. Is it a mother
and an enclosed daughter, as is the case with aphides, or
is the ciliated envelope merely a cloak? We think that
the latter is the true interpretation. The ciliated mantle
which the embryo loses, is a skin which has been thrown
off in moulting, a simple effect of age.
Thus we find in the complete evolution of a distome
an organic and a sexual age, a true alternation; the
agamous age undergoes a true moulting, the sexual age
a metamorphosis.
We have before considered the embryo as mother and
daughter coming into the world together, as we see
among the aphides; or the mother, daughter, and grand-
daughter are born together like twins; so that if the
mother or the daughter meet with an accident during
parturition, the granddaughter may be born before her
mother, and even before her grandmother.
We are now about to study some of these mysterious
travellers which have given so much trouble to natural-
TRANSMIGRATIONS AND METAMORPHOSES. 197
ists to discover their abode and determine their identity.
Considering the number of observers who have mentioned
these distomes, it is evident that these parasites must
‘be very common. We find the names of Ruysch, Leeu-
wenhoek, Swammerdam, Camper, Houttuyn, Mulder,
Heide, Biddloo, Snellen, etc., among the naturalists
who have made them a subject of study. In our own
day, the writers who have explored this territory are so
numerous that we should require more than a page
simply to give their names.
Distomes frequent, with few exceptions, all the classes
of the animal kingdom, and if their number is great
among fishes, they are not less numerous in mammals
and birds. The higher classes of animals usually inocu-
late themselves through the intermediation of molluscs,
worms, and crustaceans, and itis therefore in the ranks of
these that we must seek for their first abode. Without
admitting that their size bears some proportion to the
host which gives them shelter, still, the largest species,
the Distomum Goliath, is found in the liver of one of the
balenoptera. This distome is of the size of a large leech,
and its host does not measure less than twenty metres.
Mons. Willemoes-Suhm mentions a distome which at
the time of its cercarian evolution lives freely in the
water, and attaches itself by its sucker to the larve of
worms or copepod crustaceans, and then lodges in their
dejecta without encysting itself. This is the Distomum
ocreatum of the herring, according to Professor Moebius.
Mons. Ulialnin found in the bay of Naples another free
distome, which is also attached by its ventral sucker to
certain copepods, and which becomes the Distomum
ventricosum inhabiting many kinds of fish.
198 ANIMAL PARASITES AND MESSMATES.
Any one who wishes to make observations on dis-
tomes in the state of cercarie has: only to examine some
fresh-water molluses, either the Limnex or Planorbes
found in ponds; as he tears the animal to pieces on the
stage of a simple microscope, he will not fail to perceive
a multitude of struggling and wriggling tadpoles. Their
tails twist with each other, furl up, extend, and describe
ares of circles, as if we had a nest of serpents under our
eyes.
Each species of distome has it own cercarie, which
are scattered among as many
different inferior animals. Birds
and fishes become infested by
them in consequence of eating
these animals.
We may here cite as an
example of this class of para-
sites the Distomum hepaticum,
or liver fluke ; this species is the
most interesting to us of all the
genus; it attains the size of a
moderate leech, and habitually
Be - @me resides in the liver of the sheep.
ee age et ike ot twice In order to discover it, we have
ere sudo) ip ab iomieonly a0 examine a fresh liver.
They are usually found in the
biliary canals, where they move about like planarie. It
is always of a deep colour, and is doubtless introduced in
the state of cercaria, when the animal is drinking. M.
Willemoes-Suhm supposes that the Distomum hepaticum
has for a vehicle a small snail, the Limaz agrestis,
which the sheep swallows with the grass on which it
TRANSMIGRATIONS AND METAMORPHOSES. 199
feeds. Its principal abode is in the ruminants and
only casually in man. It is said to be unknown in
Iceland. The Distomum lanceolatum has also been found
in man. :
Dr. Bilharz, the pupil of Siebold, discovered in the
year 1851, on man, a parasite in every respect remark-
able. It belongs to the family of the Distomide, and on
account of its peculiarities, it has been made into a
genus under the name of Bilharzia. It is found in
Egypt, and lives in the vena port and in all its ramifi-
cations in man. According to Bilharz, this distomian
is dicecious, the male being of considerable size, the
female slender and delicate, which fact does not agree
with the usual characteristics of dicecious animals. At
least half of the Fellahs and Copts suffer from these
parasites; these worms, at the period when they lay
their eggs, proceed from the vena cava to the veins of
the pelvis, and after having produced very grave con-
sequences, they are at last evacuated with the urine.
Another distome was also found by Bilharz in the
intestines of a young Egyptian boy.
The largest known distome inhabits the liver of the
Balenoptera rostrata, the little whale of thirty feet in
length, which is regularly met with on the coast of
Norway. ‘The intestines of the ordinary seal often con-
tain a very curious distome, which was first observed by
Rudolphie, the D. acanthoides. The seal is also infested
by the Distomum cornus, which some have incorrectly
preferred to place in the genus Amphistoma.
Besides the distomes which inhabit the liver, there
are found but few in the mammalia, except in the
Cheiroptera: these insectivorous animals have their
200 ANIMAL PARASITES AND MESSMATES.
intestines literally full of these parasites. We have
noticed the species which regularly frequent our bats,
and it only remains to discover the insects by means of
which they are introduced ; for it is probable that these
insects are infested by cercarie during the time that they
inhabit the water. Larve and their parasites ought to
be carefully studied in the localities where bats abound.
There are few birds, especially among the gralle and
the palmipedes, which do not enclose in their intestines
a certain number of distomes. The same may almost
be said of reptiles and batrachians, but it is especially in
fishes that their number is greatly increased. We may
say that there is no fish which does not nourish some of
these trematodes. Among a portion of these, the cycle
of evolution and transmigration is perfectly known; we
may instance the Distomwn nodulosum. This worm
inhabits the intestines of the perch.
The scolex, as well as the cercaria, has its particular
characters, and we have long since found the latter in
a fresh-water molluse, the Paludinaimpura. The cercaria
is easily recognized by the presence of two particular
folds at the base of the buccal bulb, and by the trans-
-parency and the form of the extremity of the urinary
apparatus. In the adult distome, this same part of the
urinary apparatus encloses large vesicles with very dis-
tinct partitions.
We may also mention among the distomes a species
from fish, which has a great affinity with the singular dis-
tome observed by Bilharz, of which we have spoken above.
This distome inhabits the ‘‘ castagnole,” or Brama rai.
Under the opercula of this fish, the skin is folded, and
forms one or more pouches, in each of which lives a
TRANSMIGRATIONS AND METAMORPHOSES, 201
coupled distome, that is to say, by the side of each large
and fat individual, full of eggs, there is one which is
slender. It is the Distomum filicolle, to which the
name of Monostomum was at first given. We should be
correct in supposing that of these two hermaphrodite
worms one acts rather as a female, the other as a male.
It is doubtless in this sense that Steenstrup maintained
his assertion, that there are in nature no hermaphrodites.
Thus there are two kinds of distomes: the first live
in couples in a cyst, the second in couples joined
together, but at liberty; and in each case only one
individual produces eggs. These are distomes which
act reaNy like dicecious worms. We find, however, a
more remarkable instance in the Monostomumn bijugum
of Miescher. In the tumours which are formed in the
beak of the grosbeak (Fringilla), he has constantly
found two individuals; and in many cases he has sur-
prised them with the penis of one engaged in the sexual
organ of its companion. These worms, while they live
in couples, resemble each other like snails and leeches;
they are mutually fecundated, and both lay eggs.
Leuckart recognized these sexual distomes in their
eyst, in the larve of ephemerides; and Linstow noticed a
distome thus sexual and encysted in the Gammarus pulex.
The name of Monostoma has been given to some of
these trematodes which have no abdominal sucker.
One of the most curious worms of this group is the
Monostomum mutabile. Tt lives in the sub-orbitary sinus
of several aquatic birds; that is to say, in the nasal
fossee, especially of water-rails and moorhens. We
give a slightly magnified representation of them. It is
a worm resembling an elongated leaf. By compressing
202 ANIMAL PARASITES AND MESSMATES.
it slightly on the stage of the microscope, we easily dis-
cover the ovary, the matrix, and oviduct full of eggs.
By isolating some of the eggs, and crushing them gently
to break the shell, we set free the worm (Fig. 44), quite
different from the mother (Fig. 48). The former has
two eyes surrounded by a ciliated mantle, and by means
of this ciliated envelope, the monostome swims freely in
mutabile (adult). sporocyst and young cercaria, greatly magnified.
the water. If we compress it slightly, we see that in the
interior of the ciliated covering, there is still another
animal, without eyes, without cilie, and of an entirely
different form, which in its turn encloses a whole progeny.
The embryo, having long cilie in front, and in the
interior a sporocyst already full of young cercarie, is
shown in Fig. 44. It is this latter creature which the
ciliated embryo must confide to the care of others; this
she puts out to nurse with some molluse or other, until
it is fit to provide for itself in its turn. We have still to
discover the train by which the parasite must travel, in
TRANSMIGRATIONS AND METAMORPHOSES. 203
order to arrive again at the nasal fosse which are the
first cradle of the family.
We find occasionally between the feathers of some
birds tubercles of the size of a pea, and when we open
them we see in each two similar worms, placed so that
the stomach of one is applied to that of the other; this
is the monostome of which we have spoken above. These
worms are from three to four millimetres in length
(about ‘18 in.), and are found in the titmouse, the sis-
kin, the sparrow, the canary, and some other birds.
A worm very common in the intestines of the green
frog is known by the name of Amphistomum sub-clavatum.
Its cercarie are usually found in an acephalous mollusc,
known by the name of Cyclas cornea. That which
Fig. 45.—Cercaria of Amphis- Fig. 46.—Sporocyst of Amphis-
tomum sub-clavatum. tomum sub-clavatum from the
Cyclas cornea.
distinguishes the scolices of this species is the great
contractibility of the external membranes of the young
individuals; they lengthen, they shorten, they swing to
the right and the left, describing a semicircle on the
anterior half of the body (Fig. 46). We represent side
204 ANIMAL PARASITES AND MESSMATES.
by side the cerearia of this amphistome, and the adult
and sexual amphistome, as it is found in the intestines
of the frog.
Constantine Blumberg has recently published an
interesting memoir on the structure of the Amphistomum
conicum. :
A beautiful ‘trematode worm, known by the name
of Hemistomum alatum, whose antecedents have not been
ascertained, lives usually in the intestines of the fox. It
is about four or five millimétres in length (about *17in.).
Many birds harbour Holostomes which belong to the
same croup, the first state of which is not yet known.
The Holostomum macrocephalum is common in the intes-
tines of rapacious birds; it is from five to seven milli-
metres in length (about *23 of an inch).
We close the history of trematode worms by giving
the figure of a beautiful one known under the name
of Polystomum, which lives in its adult state in the
bladders of frogs (Fig. 48). Interesting observations
have recently been made on the manner in which they
are introduced into the bladder.
The worms which naturalists call Cestoids, or Cestodes
(which means, like ribbon or tape), have for their type
the tape-worm known by every one. They are very
abundant in many animals, are found in almost every
class of the animal kingdom, and are almost as common
as the distomians, of which we have just spoken. They
are introduced into animals which are vegetable-feeders,
by means of water and plants, and into carnivorous
animals by their prey. The tape-worms of the herbivora
lay eggs like the others, but their embryos have, as soon |
as they are hatched, a ciliary covering which allows them
TRANSMIGRATIONS AND METAMORPHOSES. 205
to live and move about in the water. Those of beasts of
prey are entirely different; it is by means of the prey
that they enter their hosts. Each carnivore has its own
worms, as it has its own prey which introduces them.
Vig. 47.—A Gabe eauins sub- Fig. 48.—Polystomun
clavatum of the frog. integerrimum.
Independently of these worms, the vegetable-feeders
afford lodging to some which are not their own.
206 ANIMAL PARASITES AND MESSMATES.
We have found in bats two tenie, both incompletely
developed, and occupying the digestive tube. One has
a rostellum without hooks, like the teenie of the vegetable-
feeders, the other has hooks like those of the carnivora.
These cestode parasites are observed to be of two prin-
cipal forms ; the first vesicular, like the finger of a glove
partly drawn inwards. They are always lodged in the
midst of the flesh, or in a closed organ in the middle of
a cyst; under this form the cestode worm is harboured
by a host which is to serve as a vehicle to introduce him
into his final host. He is a parasite on a journey; he is
always agamous, and usually bears the name of cysti-
cercus (Fig. 49). As to the second form, it is like a
sheer ribbon; ié attains a great
length, always occupies the
intestine, attains its com-
plete and sexual develop-
ment, and lays an innumer-
able quantity of eggs which
are disseminated with the
evacuations.
The rabbit harbours a
cysticercus which has its
final destination in the dog
(a xenosite); but imdepen-
2 dently of this stranger, it
Fig. 49.—Cysticercus; a, upper part of gives hospitality to a special
the vesicle; 6, place where the vesicle eer Ose : : :
jaabout #¢ Separate: o.neck of the tODIA Hits moestimes.. This
; d, the head, showing the -_-:
eqeserd and the ae of oe ~ is its own worm, the Tenia
pectinata, which is a nos-
tosite. All the herbivora are in a similar case; the ox
and the sheep possess a peculiar tenia of their own,
TRANSMIGRATIONS AND METAMORPHOSES. 207
besides those which they lodge for the sake of the car-
nivora. The worms of the herbivora have particular
_ characters by which they are easily known; they have
no crown of hooks.
The tenia of the wolf, which has often been con-
founded with the Tenia serrata, lives in the brain of
the sheep, and produces a disease known as the “gid.”
It was formerly said that every animal has its enemy.
We should rather say that each species has its parasites,
and each parasite has its vehicle by which it is intro-
duced.
These tape-worms are found in all the vertebrate
classes. An herbivorous animal usually serves as a
vehicle, but it more frequently carries, besides its
passengers, species which are peculiar to itself. As
the carnivorous animal is not intended to be eaten
like the herbivora, it cannot serve as a vehicle, and if by
chance its muscles enclose some passenger, he has lost
his way and that for ever.
Do the cetacea generally live on fish, and do they
become the prey of some aquatic carnivora? We have
reason to think so, from the presence of certain agamous
cestodes, which have been frequently found in too great
number to allow us to suppose that they have lost their
way in these aquatic mammals. There have been seen
in the substance of the muscles of many species, or
rather in the layer of blubber which covers the skin,
agamous cestode worms of the genus Phyllobothrium,
which can only accomplish their evolution in some large
squalus. There must then be contests between dolphins
and sharks, contests in which the dolphins are worsted,
in spite of their superiority. These Phyllobothria have
208 ANIMAL PARASITES AND MESSMATES.
been found in the Delphinus delphis, the Tursio, and the
Ziphius. As the Orca attacks the whale, and feeds
upon its flesh, there would be nothing surprising in our |
finding in these large cetacea, some agamous cestode
destined to pass through the last phase of its evolution
in this terrible carnivorous animal.
The cestode can scarcely be called a parasite under
the first vesicular form. It is sufficient for it to pass
through its first transformation in the midst of the
_ tissues, and it will remain weeks, months, even years,
without undergoing any change; it asks for nothing but
an hospitable roof; and this mysterious being, that had
often come they knew not whence, encamping rather than
lodging, always without progeny, was long since cited
by the naturalists of a former age in favour of the old
hypothesis of spontaneous generation.
It is not the same with the second form. Here the
worm, always lodged in the intestines, grows with extra-
ordinary rapidity, and fulfils all the conditions of a true
parasite. In a fertile soil it extends itself and produces
young as long as it has any life, and in no group of the
animal kingdom do we find any fecundity to be compared
to that of this worm. Boerhaave described a broad tape-
worm, three hundred ells in length. Eschricht estimates
the number of the segments of this worm as ten thou-
sand; and if we consider that each segment, or, we
should rather say, each complete worm, may perhaps
enclose thousands of eggs, we may form some idea
of the profusion of germs which can be scattered by
each individual.
To thoroughly know an animal we must have made
observations on it during all the phases of its evolution.
TRANSMIGRATIONS AND METAMORPHOSES. 209
Let us sketch these phases. All the cestodes have eggs,
usually in great number, very well protected against
external agents. They fader heat and cold, drought as
well as humidity, resist by means of their envelopes the
most violent chemical agents, preserve the faculty of
germinating, we will not say for weeks, months, and
years, but for centuries. When they first leave the egg,
we see an embryo of an oval form, transparent, composed
apparently of sarcode, contractile throughout all its
extent, and in the middle of which we perceive six stylets
arranged in pairs, and which at last move with great
rapidity.
The following is the manner in aihiole some years
since, we described these six hooked embryos produced
by a tenia of the frog, which were struggling by the side
of each other on the slide of a microscope. ‘‘The six
hooks are arranged regularly in each individual, and
move exactly in the same manner. They are very slight,
and of nearly half the diameter of the embryo. Two
occupy the median line, and unite like a single stylet;
these are nearly straight, and a little longer than the
others. They only move backwards and forwards. Their
action is like that of the parts of the mouth in certain
parasitical crustaceans, the Arguli, when they endeavour
to pierce through the tissues. They are in continual
motion to and fro. The other four hooks are similar to
each other, and differ from the first in the point, which
is curved into real hooks. They are arranged two and
two, to the right and left of the first, so that they all
meet at the base. Their movements are not the same as
those of the two first; they remain almost fixed at the
base, while they describe a quarter of a circle at the
210 ANIMAL PARASITES AND MESSMATES.
extremity. Let us imagine the six hooks, placed in front
in the same direction. The two in the centre advance,
and the two pairs placed symmetrically by the side of
them, are lowered and drawn backwards, and thus push
the body forwards.
Tt is like the dial-plate of a clock, with three hands
placed by the side of each other; that in the middle
would advance directly forward, atte the two others
would be lowered until they formed.a right angle with
the first. This is the movement which we observe in all
the stylets. The result of this is that we distinctly see
the embryo penetrate between the débris, or into the
crushed tissues which surround it. These embryos
imitate the movements of a man who wishes to get
through a window a little above him, and who, having
succeeded in passing his elbows through, pushes his body
forward by leaning them on the frame.
‘“We see the same efforts continue for hours; and we
can easily understand that there is no living tissue,
however dense it might be, except the bones, which
could not be easily penetrated by these microscopic
embryos. This explains why we so commonly find
cysticerci scattered in cysts along the intestines and
between the membranes of the mesentery, and how they .
can, by piercing the walls of the vessels, spread them-
selves into the most distant organs, by means of the
blood which conveys them. When the embryos have
once pierced these walls, they hollow out the tissues in
all directions, until they find themselves in the muscles,
or in the organ which is indicated in their itinerary.
When they have arrived at their destination, they stop
and surround themselves with a sheath; their stylets, -
TRANSMIGRATIONS AND METAMORPHOSES. FEE
which are no longer of use to them, decay; and at one
of the extremities appears a crown of new hooks quite
different from: the former ones, which will serve to
anchor their progeny in the new host into which they
may be introduced.”
Thus the vesicular worm (Fig. 50), fully formed,
and without undergoing any
change, waits till its host, or
the organ which shelters it, 1s
eaten, and then wakes up in
the stomach. Every living
cysticercus which penetrates
into the stomach, instantly
quits its torpid state; it gets
rid of its useless parts, aban-
dons its former cavity, pene-
trates into the intestine,
Fig. 50.—Vesicular worm. attaches itself by its new
hooks and its suckers to the
enclosing membranes, and grows with such rapidity,
that in less than six weeks, we often find a tape-worm
many metres in length. The vesicle which had hitherto
protected it. is abandoned, and the part which remains
with hooks and sucker is the mother which has produced
in this agamous manner the whole colony. This mother
is usually called the head of the tenia, or more properly
the scolex. As long as the mother is there, she engenders
and produces cucumerine, that is to say, proglottides,
which are the perfect and sexual state of the cestode.
We have seen among the trematodes a worm of
a particular form leave the egg, and immediately
produce a swarm of young ones, which go and live
Y12 ANIMAL PARASITES AND MESSMATES.
separately. In the cestodes all these individuals are
united in a kind of band, and are besides this joined
to the mother, which becomes the root of the family.
This root, planted in the walls of the intestine, is the
head. Thus each segment of the tenia is an individual,
and at the period of sexual maturity, this individual is
detached, goes away with the feces, spreads over the
grass or elsewhere, and thus sows far and wide the eggs
which it contains.
The teenia, as well as the other tape-worms, is generally
looked upon as an imprisoned parasite during the whole
of its existence. This isa mistake; the last stage of the
life of cestodes is a phase of liberty. The cucumerina,
or, as we have proposed to call it, the proglottis, that
is to say, the complete and sexual animal, is evacuated
with the feces; and when we notice a dog leaving:
his dung upon the grass, it is not uncommon to see
there worms which move like leeches, and whose white
colour is in strong contrast with the mass which
contains them. The duration of this last stage is very
short, it is true; but it is, nevertheless, during this
period of her life that the mother scatters the eggs
which are to disseminate the species.
We repeat that each animal has its eae and
these in their turn are not alwavs exempt from them.
We have already cited some examples of this.
Man has the dental system of a vegetable feeder ;
but, thanks to fire, which he alone knows how to produce
and maintain, he eats flesh. It is by these means that
he nourishes the solitary worm, which, by its crown
of hooks, is a cestode belonging to the carnivora, and
the Tenia mediocanellata with the Botriocephalus, which
TRANSMIGRATIONS AND METAMORPHOSES. 213
are cestodes peculiar to vegetable-feeders. As a feeder
on vegetable diet he also harbours vesicular agamous
cestodes, which are only found in him as passengers.
The Tenia serrata of the dog lives at first as a
passenger in the peritoneum of the hare and the rabbit ;
and every one knows how greedily the dogs eat the
viscera of these animals.
The cat entertains another kind of tenia, and, as we
may easily suppose, in its young state it lives as a
passenger in the mouse or the rat. Who then has
traced out for it this itinerary, and pointed out the way,
the only one by which the parasite can hope to take
possession of its proper abode? Evidently it is neither
the tape-worm nor the cat. The plan for all these
various species is marked out beforehand, and each
animal as soon as it is born knows it without being
taught.
A Danish naturalist, Mons. H. Krabbe, has just
finished a special work on cestcde worms of the genus
Tenia, and he remarks that there is no class in which
these worms are so abundant as in that of birds. It
is among the rapacious and carnivorous birds of this
class that they are less abundant. Among mammals,
the carnivora possess the greater number. This fact, as
M. Krabbe remarks very rightly, seems to indicate that
the cestodes of birds especially employ the inferior
aquatic animals as their vehicles when in their incom-
plete state.
Let us consider the solitary worm of man (Tenia
solum), it will enable us to understand all the others.
Known by the name of tenia, or solitary worm, it is, like
al] the cestodes, a marvellous association of mothers
B14 ANIMAL PARASITES AND MESSMATES.
and daughters, which are developed and vegetate im
22e
———}
———
== =
—S— ‘
=
=
ee
— I
Hoi
ca a
> rar)
Ml
=
.——}
=
=e
+
Sa
SSS
—
A £. :
2
ee
i—S
a — ve
ie
Fig. 51.— Tenia solium, or solitary worm ;
a, head, or scolex; 6, tape formed of
many individuals,the last of which, com-
pletely sexual, separate under the name
of proglottides, and represent the adult
and complete animal, Each solitary
worm is a colony,
a peaceable community.
Each segment is a com-
plete being, which encloses
within itself an entire and
very complicated appa-
ratus for the fabrication
of eggs.
We give (Figs. 51 and
52) the representation of
a solitary worm, peculiar
to man, of the natural
size; and at the side the
scolex, usually called the
head, slightly magnified.
Under its first vesicular
form the solitary worm is
Fig. 52.—a, Rostellum ; 8,
crown of hooks; ¢ c, suck-
ers; 1, scolex of the tenia
solium; 2, hooks expanded;
a, heel of the hook,
TRANSMIGRATIONS AND METAMORPHOSES. 215
planted in a provisional soil. After this it is trans-
planted into a richer soil, where it flowers and throws
out its numerous seeds. It comes to us from the flesh
of the pig, in which there lived vesicular worms, of the
size of a hazel-nut. The muscles are sometimes full
of them, and the pig is then said to be ‘‘ measly.” The
ancients noticed that the sucking-pig never takes this
disease ; and as Sus scropha is the name of the pig, the
term scrophula has the same origin as the specific name
proposed by Linnezus.
The measles in pork have been attributed to damp,
to feeding on acorns, to hereditary causes, to contagion,
even to injured corn and mouldy bread, All. these
theories we find in pathological treatises. The only true
cause, however, is the introduction of the eggs of the
Tenia solium into the intestines. If we wish to prevent
this infection, we must not permit the animal to eat
man’s excrements, nor to drink water in which sub-
stances that have become decomposed on a dung-heap
have been allowed to remain.
The cysticercus of the pig, when introduced into man,
becomes a tenia with as great certainty as the seed of a
carrot will produce this plant if sowed in suitable soil.
The observation had been for a long time made without
any explanation being given, that this parasite especially
shows itself among pork butchers and cooks. This is
because these persons, more frequently than others,
handle raw pork. The same observation has been made
respecting children who have made use of the gravy
of raw meat. Minced raw meat (conserve de Damas)
has been prescribed with success in chronic diarrhea.
The tape-worm has often been known to make
11
216 ANIMAL PARASITES AND MESSMATES.
its appearance after this treatment, as may well be
supposed. Tenia helminthosis is constant and general
in Abyssinia, and they there commonly eat raw beef.
Those who do not eat meat, as the monks of certain
orders there, who live only on fish and flour, never
have the tenia. Ruppell and many others have noticed
this fact. Mons. Kuchenmeister says that at Nordhausen,
in the Hartz, as well as throughout all Thuringia,
measles are very prevalent among pigs; and as the
people are in the habit of eating minced pork, both
raw and cooked, spread on bread for breakfast, this
country may be looked upon as the Abyssinia of the
north.
The doctor at Zittau caused a man who was con-
demned. to death, to take, seventy-two hours before his
execution, some cellular cysticerci from a measled pig;
and he found in the duodenum of the man four young
teenie, and six others in the water in which they had
washed the intestines. The latter had no hooks, but
those of the former had some in every respect similar to
those of the T’znia soliwn.
We have ourselves caused a pig to swallow eggs of
the tenia, and have given it the measles. Messrs.
Kuchenmeister and Haubner, who were ordered by the
government of Saxony to make some experiments, also
caused three pigs to swallow eggs of the Tznia solium,
and two of these were affected with measles.