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THE INTERNATIONAL SCIENTIFIC SERIES.
VOLUME XIX.

XIX.

THE INTERNATIONAL SCIENTIFIC SERIES.
Works already Published.

FORMS OF WATER, tn Ctoups, Ran, Rivers, Ice, AND GLACIERS.
By Prof. Joun Tynpatt, LL. D., F. R.S. rvol. Cloth. Price, $1.50.

PHYSICS AND POLITICS; or, THOUGHTS ON THE APPLICATION OF
THE PRINCIPLES OF “ NATURAL SELECTION’”’ AND ‘ INHERITANCE ” TO
PouiricaL SoctETY. By WALTER BaGEHoT, Esq., author of ‘The
English Constitution.” 1 vol. Cloth. Price, $1.50.

FOODS. By Evwarp Smits, M. D., LL. B., F. R. S. xvol. Cloth.
Price, $1.75.

MIND AND BODY: THE THEORIES OF THEIR RELATIONS. By ALEX.
Bain, LL. D., Professor of Logic in the University of Aberdeen. 1vol.,
azmo. Cloth. Price, $1.50.

THE STUDY OF SOCIOLOGY. By Hersert Spencer. Price,
$1.50.

THE NEW CHEMISTRY. By Prof. Jostau P. Cooke, Jr., of Harvard
University. 1vol.,rzmo. Cloth. Price, $2.00.

THE CONSERVATION OF ENERGY. By Prof. BALFour STEw-
ART, LL. D., F.R.S. 1vol, z2mo. Cloth. Price, $1.50.

ANIMAL LOCOMOTION; or, Watxinc, SWIMMING, AND FLING,
witH a DISSERTATION ON AfrRonautics. By J. Bett PETTIGREW,
M.D., F.R.S.E, F.R. C. P. E. 1 vol, x2mo. Fully illustrated.
Price, $1.75. .

RESPONSIBILITY IN MENTAL DISEASE. By Henry Maups-
Ley, M.D. 1vol.,z2mo. Cloth. Price, $1.50.

THE SCIENCE OF LAW. By Prof. SHELDon Amos. 1 vol., x2mo.
Cloth. Price, $1.75. 2

ANIMAL MECHANISM. A TREATISE ON TERRESTRIAL AND AERIAL
Locomotion. By E. J. Marey. With rr7 Illustrations. Price, $1.75.

THE HISTORY OF THE CONFLICT BETWEEN RELIGION
AND SCIENCE. By Joun Ww. Draper, M. I)., LL. D., author ot
“The Intellectual Development of Europe.” Price, $1.75.

THE DOCTRINE OF DESCENT, AND DARWINISM. By Prof.
Oscar Scumivt, Strasburg University. Price, $1.50.

THE CHEMISTRY OF LIGHT AND PHOTOGRAPHY. In its
APPLICATION. TO ART, SCIENCE, AND InDusTRY. By Dr. HERMANN
VocEL. 100 Illustrations. Price, $2.00.

FUNGI; tuerr Nature, INFLUENCE, AND Uses. By M. C. Cooke,
M.A., LL.D. Edited by Rev. M. J. Berxetey, M.A.,F.L.S. With
10g Illustrations. Price, $1.50.

THE LIFE AND GROWTH OF LANGUAGE. By Prof. W. D.
Wuirney, of Yale College. Price, $1.50.

MONEY AND THE MECHANISM OF EXCHANGE. By W.
STANLEY Jevons, M. A., F.R.S., Professor of Logic and Political
Economy in the Owens College, Manchester. Price, $2.75.

THE NATURE OF LIGHT, wiry a GENERAL ACCOUNT OF PHYSICAL
Optics. By Dr. EvGene Lommet, Professor of Physics in the Uni-
versity of Erlangen. With 188 Illustrations and a Plate of Spectra in
Chromolithography. Price, $2.00.

ANIMAL PARASITES AND MESSMATES. By Monsieur Van
BrNepDEN, Professor of the University of Louvain, Correspondent of the
Institute of France. With 83 Illustrations. (J press.) .

‘THE INTERNATIONAL SCIENTIFIC SERIES.

ANIMAL PARASITES AND MESSMATES.

BY

poor ‘AN BENEDEN,

PROFESSOR AT THE UNIVERSITY OF LOUVAIN, CORRESPONDENT OF THE INSTITUTE OF
FERANOE,

WITH EIGHTY-THREE ILLUSTRATIONS.

NEW YORK:
D. APPLETON AND COMPANY,
549 & 551 BROADWAY.
1876.

A155 22.

CONTENTS.

INTRODUCTION.

Adaptation of Food to Animals—Animal Manufacturers—Brigands—
Messmates—Mutualists—Theory of Spontaneous Generation ...

CHAPTER I.
ANIMAL MESSMATES,

Definition—Free Messmates—Fixed Messmates seu wee eee

CHAPTER ITI.
FREE MESSMATES.

Found in all Classes—Fierasfers in Holothuride—Pilot Fish—
Remora—Crustacean Messmates—Poisoning by Mussels—Pearl
Mussel, and small Crab—Dromie—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 ... ae vee ae eee

CHAPTER ITI.
IXED MESSMATES.

Cirrhipedes—Importance 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 we eee can eve eee toe aes

PAGE

xiii

53

viii CONTENTS.

CHAPTER IV.
MUTUALISTS.
PACE

Definition — Ricinide—Trichodectes of Dog harbouring Larva of
Tenia—Arguli—Caliguli—A ncei— Pranize— Cyami—Nematode
Mutualists—Strange form of Histriobdelle-Egyptian Distome
in Man wes ee ies ae ase see os we 68

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 ... eas toe eee ar w. 85

CHAPTER VI.
PARASITES FREE DURING THEIR WHOLE LIFE.

Leeches —Vampires—Cylicobdellaa—Branchellions — Gnats — Black-
flies—Mosquitoes—Gnats in high Latitudes—Tsetse—Ox-flies—
Pteropti—Nycteribie—Bugs—Lice—Fleas—Itch Insect—Acari
on Beetles and Bees—Cheyletus eruditus wee ves .. 107

CHAPTER VII.
PARASITES FREE WHILE YOUNG.

Isopod Parasites —Chigoe— Ticks— Pigeon-mite— Bopyridses—Ich-
thoxenus — Peltogasters —Tracheliastes—Penellax—Lerneans—
Guinea-worm — Leptodera, of Snail— Nematodes in Bones—
Lichnophoree—Gregarinze ste aie Seen wes . 138

CHAPTER VIII.
PARASITES THAT ARE FREE WHEN OLD.

Utility of Ichneumons—Scolie of Tan-beetles—Scolyti of Seychelles
Cocoa-nut Trees— Elms at Brussels destroyed by Scolyti

CONTENTS. ix

PAGE
—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 Sea ae oe 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 Cercaris—Passage from
one Host to another — Distomes — Flukes — Hemistomes —
Amphistomes—Tenisw of the Dog and Wolf—Hydatids—Txnia
solium in Man—Cysticercus of Pig—Cysticercus of Rabbit and
Hare passing into Dog—Ccoenurus of Sheep—Bothriocephalus—
Linguatula in Negro—Strongyli—Trichinw—Panic in Germany
—Vibriones in Corn—Echiuorrhynchus—Dicyema oe +. 183

CHAPTER X.
PARASITES DURING THEIR WHOLE LIFE.

Strepsitera—Stylops—Rhipiptera—Tristomide— 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

2.—Ricinus of the Pygarg

3.—Caligulus elegans, female: ditto, patil size ...

4.—Different forms of the Bite of a Leech .

5,—Sucker and jaws
6.—Anatomy of Leech ...
7.—Antenna of Gnat
8.—Gnat, male and female
9, 10.—Lucilia hominivora
11 —Ozfy ee a
12.—Antenna of Ox. ae,

13.—Blue-fly oes is .

14.—Flesh-fly ie
15.—House-fly... sos

16.—Bed-bug_... abi vee

17.—Louse sin sae a
18.—Louse—Suckers ... was
19.—Ditto—Claw

20.—Flea (Pulex giao ws

21.—Itch-mite ... eee
22.—Diitto, fennala—hack * view .
23.—Ditto, male—back view ...
24.—Geographical water-mite
25.—Book-mite ... és as
* 26.—Chigoe, male tee vo
27.—Ditto, head wie tee
28.—Ditto, female a one
29.—Phryxus Rathkei ... one

LIST OF ILLUSTRATIONS.

ric.

30.—Tracheliastes of Cyprinids oe ove eos ase nee
31.—Lernea branchialis attached to Morrhua luscus

32, —Young Guinea-worm, showing Mouth, Tail, and section of Body

33.—Gregarinez of Nemertes ... ve Per

84.—Sac with Psorospermiz from Beta aificinadés eo ee

35.—Stylorhynchus oligacanthus from Dragon-fly uf oo

36.—Horse-fly, showing also Anterior and Posterior Extremity ...

37.—Macaco Worm or és to oe

38.—Melophagus of the Sheep: oe <—o ea aes wee
39.—Lipoptena of Stag Sam see ie atl
40.—Gordius aquaticus a 65
41.—Monostomum pancubdatiic! soenacsit with Cecoart im...
42.—Liver fluke Ha es sie oes se
43.—Monostomum mutabile ... “a eee tee ed ae
44.—Ditto, ciliated Embryo and young Ghiearis as ies
45.—Cercaria of Amphistoma sub-clavatum ... we eee a
46.—Sporocyst of Amphistoma sub-clavatum ... ads on wea
47,—Ditto, from Frog... a ne ee =i aes eee
48.—Polystomum integerrimum eee eee eee
49.—Cysticercus ake eee ec oe , avs
50.—Vesicular Worm... eas Fs sot “es

51.,—Tape-worm (Tenia solium), showing Scolex Sat Prowlothities
52. —Ditto, Rostellum and Suckers... Pr ide

53.—Teonia medio-canellata ... ae beg wae eve oes
54,—Coonurus of Sheep, and fivdatia... oe eee ace c
55.—Scolex of Twnia echinococcus.... wea eos

56.—Tenia echinococcus from the Pig Ke eee . .
57.—Ditto, from the Dog axe ee oer ove ‘ or

58.—Bothriocephalus latus aes sas toe ats eee
59.—Scolex of ditto ise aes ies ves

60.—Egg of ditto eee ‘ia ee rc ne ase

61.—Tenia variabilis from Snipe ive ees sa ose ave
62.—Ditto, more highly magnified ese ass
63.—Tetrarhynchus appendiculatus os the Plates... ave ase
64.—Hook of Linguatula sh ee ves ee eee eos
65.—Linguatula, showing Hooks aes ove wus toe ase
66.-—Strongylus gigas, female ... eve ae ae

67.— Ascaris lumbricoides; also Head, ‘Tail, and Body ins eee
68.—Trichocephalus from Man ees was a <o ae

xii LIST OF ILLUSTRATIONS.

FIG.

69.—Oxyuris vermicularis, natural size and magnified
70.—Trichina, free to ee oo
71.—Trichina encysted in Muscle ae oe eee
72.—Echinorhynchus proteus .... ov. ”
73.—Sac with Psorospermie from Sepia omeinalts ae
74.—Gregarinez from Nemertes Gesseriensis oes

75.—Stylorhynchus oligacanthus dis aes tee
76.—Dicyema Krohbnii from Sepia officinalis ... oe
77.—Stylops es woe oe
78.—Ditto, with Eahegos bes ves

79.—Larva of Black Stylops_... ies sea
80.—Cochineal Insects, male... aes oes
81.—Ditto, female ats ets ie ae
82.—Aphis

83.—Rose Aphis, male and fomale ws ae es

INTRODUCTION.

oo

“ 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 archeologist.

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 uninvited 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 is 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? Either 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, XVli

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 flésh 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

XVill : 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. xix

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-d-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. XXi

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

xxii 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 which 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. oan

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
gloomy 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 stercorari#e, 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 stercorarie 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-

Xxvl 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 as
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 more profound also is our conviction, that

eee .
XXV1 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.

Tur 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 dtess, 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 Fierasfer hornet is found
in the Stichopus tuberculosus.

The holothurie 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 holothurie
in the Philippine Islands which bore a considerable
resemblance, in this respect, to an hotel with its
table d’héte.

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 holothurie,
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 holothuria, 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
Wurizburg 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 Miller, usually lives a myxinoid fish, called
Einchelyophis 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 own rank. 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, q

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
(Actinia 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-

8 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 little.
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 bookei. 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 branchie, 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 eges, 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 Physaliew, 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 Scombride, 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 medusa. 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 Labraw 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.Jouan, when in the
Indian Sea, on October 26th, 1871, in 18° 20’ N. lat.,
and 60° 80’ 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 meduse 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. 11

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? Asin 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
greedily. 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
legions of small animals which serve as the police of the
sea-shore, purifying the waters of the ocean of all or-
ganic 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 skim; 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 egg 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 mollusc. 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 modiola, and we have never met with
any without their crabs. We have long since deposited

FREE MESSMATES. 17

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,
s0 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 Tridacn#, 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 macrours allied to the Pontonia, to
which he has given the name of Conchodytes; the
Conchodytes tridacne inhabits the Zridacna squamosa ;
the Conchodytes meleagrine, 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. Fischerti) ; so that these little crabs, the friends of the
molluses, 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, Guérim—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 mollusc, 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 1688 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

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 mollusc, 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 holothurie, of which we have already spoken,
appear to afford an abode to many animals: indepen-

FREE MESSMATES. 21

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 living 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 Pecilopora 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
Haliotid#, and another on the body of a holothuria. On
the coasts of Brazil, F. Muller, during his abode at
Desterro, saw some Porcellan# 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
itgelf, 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 medusex, Sir J. G. Dalyell

23, ANIMAL PARASITES AND MESSMATES.

has made us acquainted with another messmate of the
medusx which greatly resembles an Idothea.

Another kind of commensalism is that of the
Dromiz. 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 Aleyonium, 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.
Sertularie, Corynes, Alg#, develop themselves on this
Alcyonium, 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
greatest 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 Palamon 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,
8

t

24 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 Cenobit# 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 amphipods,
the Phronime, which choose for themselves 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
give 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 cxpansion furnished by the 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
yematkable for the good understanding which exists
between himself and his acolyte—he is a model Amphi-
tryon. Lhieut.-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 mancuvres with
all the delicacy of which he is capable, to make the
anemone change its shell; he assists it in 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 actinia; a curious
cirrhipede often establishes itself on the body of the
purus, 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 Alcyonium
(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.

In 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 Kénigsberg df-
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
on cirrhipedes (Sacculinides) 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-
crab 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 Gebie live like the Callia-

FREE MESSMATES 29

nasse, hidden in the mud. The Limnaria lignorwm 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 (ga 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 (Aga spongiophila) which
lives in the magnificent sponge, the Euplectella. 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

FREE MESSMATES. 31

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 Hpichtys giganteus, which lives
on a fish of the Indian Archipelago, and the Ichthyoxenus
Jellinghausiit, 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 Stromatei. 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 Trachina 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 meduse,
in order to gain support. We find on our own coasts the

FREE MESSMATES. 33

Hyperina Latreillii, lodged in the superb Rhizostoma,
which regularly appears in the later season of the year
on the coast of Ostend; and a long time since, in 1776,
O. F. Miller gave to a species of this genus the name of
Hyperina medusarum. Mr. Alexander Agassiz once
found a Hyperina on the disc 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 Mébius 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, and in 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

34 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. Mr. 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 Vauzéme, 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 Cyami seem to us to live on the
whale, as the Arguli 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 Tubicinella 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 Hydractini#, and other polyps, while at
a later period they frequent molluscs or higher classes;
Allman mentions the case of a Phozichilidium 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 Staurosoma
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 Oligochexts
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

&6 ANIMAL PARASITES AND MESSMATES.

Histriobdellz, 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
Echinoderms, 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 Eulima brevicula, on the Archaster
typicus of the Uvea Islands, in the Pacific Ocean. The
molluses, known by the name of Stylifer, have the same
mode of life; they have been observed in the Asteria,
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 incapable
of nourishing themselves otherwise than at the expense
of their host. However this may be, these molluscs,

FREE MESSMATES. 37

ranged alternately among the Phasianelle, the Turritelle,
the Cerithia, the Pyramidelle, the Scalari#, the Ris-
soairia, or 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 comatule, 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 molluscs 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 eggs, whence this
great 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
has dedicated to the illustrious physiologist of Berlin,
and which he found attached to the cloacal sac of the
Holothuria edulis.

38 ANIMAL PARASITES AND MESSMATES.

The true relation between these moliuscs 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 Cyprea, which
one would certainly not expect to find in this category ;
it lives among the Viti Islands, in the compartments of
the. Milithewa 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 (Ocotes 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 calcareous tube similar to the shell, of which
it appears to be the continuation, and which allows it

FREE MESSMATES. 39

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
like 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 Anadonte are parasites, and he
proposed for them the name oi Glochidiwm. 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.* In fact the young anodonts have,

* I owe this observation to Dr. W. 8S. 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 Crenelle 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, Lernewans 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 Sphaerium 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 Aem-
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 Bafini, 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 Lorosoma. 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. Claparéde and Keferstein have observed a
species, the Loxosoma singulare, on a capitellian annelid,
of the genus Notomastus, at St. Vaast-la-~Hogue, on the
coast of Normandy. After this, Claparéde found another
species, the Loxosoma Kefersteinii, 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
great 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 one.

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
cilie. 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 same 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 Miller ob-
served on the coast of Brazil, begging assistance from a
poor Lepas anatifera. Many Polynoés live upon other
annelids; the Harmothoé Malmgrent on the sheath of
the Chastopterus insignis, the Antinoe nobilis on the case
of the Terebella nebulosa. Prof. Ray Lankester hag
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 flexuosa. 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 whole

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 mess-
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 Inown 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 undér 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 Distomum
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. It is 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
eges of some ordinary crabs of our coasts (Carcinus
menas), 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. It is not known whether it plays the same part
as the Histriobdella 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 1873, 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 Turbellari#. 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 considered 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 CErsted, 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-labourer

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 Liitken
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 loca. Another species
(Oph. mirabilis) from Panama, infests certain Gorgonie
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 Hemiewryale 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 Geryoni#
produce Ciginide 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 Gorgoniz, which it invades
and stifles, as the lianas strangle the tree over which
they spread themselves. But these same Gerardie 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, Euplectella aspergillwn, 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
Euplectell# 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
Carpenter; and I have in my possession a fine specimen
which I owe to his generosity, and keep as a sowvenir 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 Thoasa.

The cliones are real lodgers which lead us to the
Saxicave, 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 tubularia.
The crown of the tubularia is extended at the entrance
of the 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 Euglena,
and still more the Distigma tenax, Ehr.

( 53 )

CHAPTER III.

FIXED MESSMATES.

Tue 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 preseni
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 disgust 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
case 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 live 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 regine, 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 Megaptere 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. There is 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 néw genus of Coronulide which

58 ANIMAL PARASITES AND MESSMATES.

inhabits the coast of California, on the singular mysticete
recently distinguished by the name of Rhachiancctes
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 Anclasma 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, m order to recognize their parentage.
Other cirrhipedes establish themselves on neighbours
of their own class, and we also find crustaceans upon
other crustaceans. A pretty genus lives near Cape Verd
on the carapace of a large lobster, and spreads itself
on the centre of the back like a bouquet of flowers.
My son has procured some very fine specimens, an

FIXED MESSMATES. 59

account of which he witl publish, together with the other
materials which he has collected during his passage across
the Atlantic. Mr. John Denis Macdonald found in
abundance on the branchie of a crab in Australia, the
Neptunus pelagicus, which he places between the Lepas
and the Dichelaspis.

The most singular, if not the most interesting of all
these cirrhipedes, are the Galle, which appear under
the tail of crabs or the abdomen of pazuri, and which
zoologists designate under the names of Peltogaster or
Sacculina. They are found in both hemispheres. The
recurrent development is so complete, that we can no
longer distinguish any organic apparatus unless it be
that of reproduction, and the whole body is a mere case
enclosing within its walls eggs and spermatozoids. We
see them very frequently under the abdomen of the crabs
of our coasts, or even on the segments of the bodies
of paguri. Mons. A. Giard has lately studied these
animals. It is during the coupling season, according to
him, that the Peltogasters establish themselves upon the
crabs. Professor Semper has brought back quite a collec-
tion of them from his voyage to the Philippine Islands,
and has entrusted them to one of his pupils, Dr. Kuss-
mann, for the purposes of study. We heard him with great
interest, at the late Congress at Wiesbaden, explain with
remarkable clearness the results of his learned and
conscientious observations. We do not think that we
shall be wrong in adding that, for a long time, we shall
see nothing better or more complete on this subject. All
those cirrhipedes which adhere by their head to the skin
of their host, by means of filaments, are now designated
by the name of Rhizocephala,

60 ANIMAL PARASITES AND MESSMATES.

A curious opinion, quite recently expressed by a
naturalist, Mons. Giard, and which is a sign of the times,
is that the Peltogaster of the Pagurus has become a
Sacculina on the crab; the host having been transformed,
its acolyte has done the same thing under the same
influence.

Professor Semper has also found among the Philip-
pine Islands, isopod crustaceans living as messmates
after the manner of the peltogasters. Two cirrhipedes
of the family of Peltogaster, the Sylon Hippolytes and the
Sylon Pandali, have been found by Mons. Sars under the
abdomen of the Pandalus brevirostris.

There are cirrhipedes on the gasteropod molluscs.
The Concholepas Peruviana, that beautiful shell which has
long been considered a rarity in our collections, is fre-
quented by the Cryptophiolus minutus, only a sixth of an
inch in length. The Scalpella often inhabit the Sertu-
larie and other polyps; Oxynasps, Creusie, Pyrgome,
and Lithotrye inhabit corals. Certain kinds of sponges
are regularly invaded by the Acastwe of Leach, eight
species of which are mentioned by Darwin. As we find
elsewhere parasites on parasites, here also we find mess-
mates on messmates; on the common anatifa we per-
ceive other genera, and on the Diadema of the North
Pacific, we almost always see Otions and Cineras. The
Protolepas bivincta also, a fifth of an inch in length, lives
as a messmate in the mouth of the Alepas cornuta; and
the Elminius of Leach also inhabits other cirrhipedes.
The Hemioniscus balani, which Goodsir had taken some
years ago for the male of the Balanus, is a messmate on
these cirrhipedes. Parasites also are found in mess-
mates; the soldier-crab gives lodging to the sexual

FIXED MESSMATES. 61

Eustoma truncata in it8 interior. A macrourous crus-
tacean which we ought to mention here, the Galathea
spinirostris, Dana, frequents a comatula, the colour of
which it assumes; it is the same without doubt with
the Pisa Styx, which lives on a polyp known by the
name of Melitwa ochracea.

If we pass from the crustaceans to the molluscs, we
have to notice in the first place an elegant gasteropod,
the Phyllirhoa bucephala, which carries on its head a
singular appendage, the nature of which has only lately
been known; J. Miller took it at first for a medusa, then
he abandoned this opinion, when at length Mons. Krohn
referred it definitively to the lower polyps; it differs
from its congeners only by its form, its tentacular cirrhi,
and its mode of life: it is the Mnestra parasites. There
are a great number of acephalous molluscs, which we
might mention as messmates, but we will only refer to the
Crenell# which are regularly found in the substance of
sponges.

The Philomedusa Vogtit of Fr. Muller, which lives on
the Haleampa Fultoni, undoubtedly deserves to be men-
tioned here as a fixed messmate. Many bryozoa spread
themselves over marine animals, and often engage in a
deadly struggle with their patron. But among all these
bryozoa we must mention an animal very common on
the sea-shore at Ostend, and which one would take for a
dried leaf, the Flustra membranacea. On the surface of
these imitative leaves are found little bouquets of other
bryozoa, which are either Crisie or Scrupocellaneg. An-
other kind, which has also passed for a gelatinous plant,
bears the name of Halodactylus. Without any micro -
scopic study, one can obtain an idea of these colonies.

62 ANIMAL PARASITES AND MESSMATES.

One of these Halodactyles spreads itself upon the stalk
of a Sertularia, all the inhabitants of which it stifles, so
that it is the victim himself who serves as a guardian to
the invader.

These Halodactyli are very widely spread over the
Northern Seas, and often establish themselves on the
large horse-hoof oyster. Michelin has noticed under
the name of parasite a fossil cellepore from the saltpits of
Touraine and Anjou, which entirely surrounds the shell
of a gasteropod; in order to prevent its patron from dying
of hunger, the bryozoon develops itself around the mouth
like a gallery, and prolongs its last spiral. This Celle-
pora parasitica has evidently a place here.

Many of these messmate bryozoa are found in a, fossil
state in the crag of the Antwerp basin.

We have still to mention among fixed messmates
many polyps, some of which are very remarkable. Thus,
many naturalists speak of vast colonies of polyps in
which lodge various animals which shelter themselves
there like paguri in deserted shells.

Among these are the colonies of which Forster
speaks, which are not less than three feet in diameter,
and fifteen feet in height, with a crown of eighteen feet
in diameter. Dana also makes mention of an Astrwa
of twelve feet in height, and of Porites twenty feet high,
which contain more than five millions of individuals,
among which a number of animals come to take refuge.

The Museum of Natural History at Paris is in
possession of a superb specimen of Porites conglomerata :
in the middle of the colony lodges a Tridacna (Trid.
corallicola, Val.) like a pagurus under a forest of
hydractinie. This remarkable polyp was brought from

FIXED MESSMATES. 63

the Seychelles Islands by Mons. L. Rousseau. It is
not impossible that pinnotheres live in this same
tridacna, and that we have there a fresh example
of messmate within messmate.

In the Bay of Massachusetts, on the coast of New
England, another curious messmate lives at great depths ;
Dana has lately described it, under the name of Epizo-
anthus Americanus, V. It establishes itself in the
Lupagurus pubescens. The Sertularia parasitica of the
gulf of Naples, from which I have formed the genus
Corydendrium, is a messmate after the manner of an
infinite number of other polyps. In closing this list,
we shall mention a polyp, named Halicondria suberea,
and the Actinia carcinopodus of Otto, which inhabit an
univalve mollusc; as also the Hetcrosammie# and the
Heterocyathi of the family of Turbinolide, which lodge
in a trochoid shell.

The sponges, placed by naturalists by turns among
plants or on the confines of the animal kingdom, are
now generally regarded as polyps; this is the opinion
expressed by Haeckel, who wishes at the same time to
replace the term Calenterata by that of Zoophytes.
The learned naturalist of Jena, when making this pro-
position, should have remembered that in 1859 we
placed the sponges in the group of polyps, as the lowest
in the scale; and that we proposed, from the time when
the acalephe were recognized to be adult polyps, to
designate all these animals under the name of Polyps.
Some time after, R. Leuckart proposed the appellation
Coelenterate Polyps, which has been generally received.
Professor Haeckel would have lost nothing by acknow-
ledging that in 1873 he arrived at a result similar to

64 ANIMAL PARASITES AND MESSMATES.

that to which I had come twenty years before, and that
it is not a very happy innovation to change the term
polyps for zoophytes. It is the more surprising that this
naturalist has forgotten to quote my opinion, since at the
congress of naturalists at Hanover in 1866, I had placed
this question on the agenda for an ordinary meeting.

I maintained, in opposition to the opinion of the
naturalists whose authority had been especially recog-
nized in the matter (Osc. Schmidt, who was present,
among others), that sponges are lower polyps, whether
they are regarded as to their development or their
organization. .

This group, so remarkable in form, so varied in
colour and appearance, very often affords examples of
animals which live with them as true messmates; and
we find the same relations established between them in
both hemispheres. As we observe rhizophales on crabs
and soldier-crabs, and pinnotheres on bivalve molluscs,
so we find that the sponges of the Indian Seas or of
Japan harbour the same messmates which we discover
on them in the Northern Seas or the Atlantic.

In the sea of Japan is found a very remarkable
sponge, generally known by the name of Hyalonema.
It is a bundle of spicules like threads of glass, which
seem artificially tied together, and on the surface of
which we regularly find a polyp of the genus Polythoa.
The nature of this sponge, and its relations with the
polyps which surround it, have been discussed for many
years. Ehrenberg had recognized the polyp Polythoa
around the spicules, but the Hyalonema was considered
by him as an artificial product. The Polythoze were
regarded as only a case in which had been placed this

FIXED ME3SMATES. 65

bundle of spicules. The learned microscopist of Berlin
had even thought that he had found the proof of this
opinion in the presence of woollen threads which were
observed in a specimen which Mons. Barbosa du Bocage
had sent him from Lisbon. Woollen threads had indeed
adhered to the spicules of Hyalonema, but they came
from the fishermen, who, when they drew these sponges
from the water, placed them carefully in their bosoms
under their woollen jerseys.

Dr. Gray, of the British Museum, considers the
sponge as a parasite of the Polythoa, and that the
bundle of spicules belongs, not to the sponge, but to
the polyp. The most learned naturalist on the subject
of sponges, Mr. Bowerbank, expresses a different opinion.
The sponge and its spicules, according to him, are but a
single body, and the polyps are only a part of it. The
supposed polyps would only form a cloacal system for
the use of the sponge colony.

Valenciennes, guided no doubt by the observations
of Philippe Poteau, was the first to recognise the nature
of the sponge and its spicules, but it is to Max Schultze
that we must give the credit of distinguishing the true
character of this extraordinary marine production. He
has shown that the bundle is formed by the extraordi-
narily long spicules of the sponge, and that the polyp
establishes itself upon it, by forming a sheath around
the bundle. .

The fact is no longer doubted by any one, that the
long spicules form part of the sponge, and that the
polyp establishes itself on a part of the colony. But
science rarely advances by a single stride, and Max
Schultze, like his predecessors, mistook the top of the

66 ANIMAL PARASITES AND MESSMATES.

sponge for the bottom; Professor Loven has shown the
true pose of the Hyalonema, and this he has effected
by means of a small specimen from the Northern
Sea. ,

Semper found a new Ciga, to which he gave the
specific name of Hirsuta, in an enlarged canal of the
new Hyalonema of the Philippine Islands, which he
dedicated to Mons. Schultze.

The Adriatic also produces a species of the same
genus (Polythoa) which inhabits, like that of the Chinese
Sea, a sponge to which the name of Azinella has been
given. These Polythoe are only found on the Axinelle,
‘says Osc. Schmidt, who has especially studied the sponges
of this sea and of the Mediterranean. Professor Gill
mentioned at the last meeting of the scientific congress
at Portland (1873), a new Hyalonema found on the coast
of North America by the fishery commission of the
United States. A memoir on these sponges, interesting
in a systematic point of view, is due to the pens of
Herklots and of Marshall.

We think that we ought to place among fixed mess-

: mates ® very problematical
organism which lives on Ser-
tularie, especially on the
Sertularia abietina, and which
Strethill Wright has desig-
nated by the name of Core-
thria sertularia. Claparéde
has given to this singular
animal the more expressive
name of Ophiodendrum abie-

9

Fig. 1.—Ophiodendrum abietinum
on Sertularia abietina. tinum.

FIXED MESSMATES. 67

We have regularly found it on the Sertularia abietina
at Ostend, every time that we have had an opportunity
of observing these polyps immediately that they have
been raised from the bottom of the sea. It is an
organism whose affinities are not yet established.

68 ANIMAL PARASITES AND MESSMATES.

CHAPTER IV.
MUTUALISTS.

In this chapter we bring together animals which live on
each other, without being either parasites or messmates ;
many of them are towed along by others; some render
each other mutual services, others again take advantage
of some assistance which their companions can give
them; some afford each other an asylum, and some are
found which have sympathetic bonds which always draw
them together. They are usually confounded with para-
sites or messmates.

Many insects shelter themselves in the fur of the
mammalia, or in the down of birds, and remove from
the hair and the feathers the pellicle and epidermal débris
which encumber them. At the same time they minister
to the outward appearance of their host, and are of great
utility to him in a hygienic point of view.

Those which live in the water have other guardians:
instead of insects, we find a number of crustaceans
which establish themselves on fishes, and if there are
no scales of the epidermis which annoy them, there
are mucosities which are incessantly renewed in order
to protect the skin from the continual action of the
water.

MUTUALISTS. 69

We find many on the surface of the scales, and others
which conceal themselves at the bottom of mucous
canals. We have brought together only a few examples,
and there are certain others which are mentioned else-
where, but which ought more properly to be placed
here.

The insects long known under the name of Ricini,
and to which many other appellations have been given,
deserve to figure in the first rank in this group. They
have always perplexed entomologists, who seem to
consider them as parasites allied to acaride and lice.
It has, however, been long known that they have no
trunk to suck with, and that they have two small scaly
teeth, which rather serve for the purpose of biting. A
long time since, the examination of their stomach
proved that they contain only morsels of skin instead
of blood. This has induced many entomologists to
place them in the same order as grasshoppers, that of
Orthoptera.

Lyonet has given figures of several of hide which
he studied with the care which he so well knew how to
employ in his anatomical investigations; and in 1818
Nitzsch, a professor at Gottingen, had brought together
so great a number of them, that it required several days
to examine his collection; he began the publication of
his catalogue, but has not had time to finish it. Several
other entomologists and anatomists have since taken up
the subject. —

We owe the description of several hundred species to
Mr. Denny. Mons. F. Rudow has lately made known
a great number of species which he has collected from

70 ANIMAL PARASITES AND MESSMATES.

the skins of birds coming from Japan, Australia, Africa,
and the two Americas.

Professor Grube, of Breslau, has published the
description of the insects and acaride found during the
travels of Middendorf in Siberia. These descriptions
relate especially to the Philoptere of birds, the Pedi-
culine of the mammalia, a flea of the Mustela Siberica,
and an acarus of the Lemmus. Quite recently, an
American naturalist, Mr. Packard, who has undertaken
the study of so many different subjects, has published
in the ‘‘American Naturalist” the description, accom-
panied by an engraving, of the Menopon picicola, found
on the Picoides Arcticus from the lower Geyser basin,
Wyoming territory, also of the Goniodes Merriamanus,
the Tetrao Richardsoni, and the Goniodes mephitidis,
found on a Mephitis from Fire-Hole Basin, Wyoming
territory; of the Nirmus buteonivorus, from a Buteo
Swainsonii; and of Docophorus Syrnti, from Syrnium
nebulosum.

A great number of these insects live between the
feathers of birds, and can be more easily observed, since
they detach themselves after the death of their host.
They are easily found on the skins of birds prepared for
museums. These ticks form a family under the name of
Riciniz, and this family is divided into two parts, the
Liotheide and the Philopteride.

Among the many generic divisions, one of the most
interesting has received the name of Trichodectes ; it
contains twenty species, one of which lives on the dog,
another on the cat, another on the ox; in a word,
we discover a distinct species on each of the domestic

MUTUALISTS. val

mammals. It has been said that the phthiriasis of the
cat is occasioned by the abundance of ricini. The
trichodectes of the dog has. lately attracted the espe-
cial notice of naturalists, and that from the following
circumstances.

There is no tape-worm more common in the dog than
the Tenia cucunerina. But whence comes it? How is it
introduced ? This had been an enigma for many years, at
the time when I dissected some dogs infested with Tenia
serrata, in the Museum of Natural History at Paris.
Together with the Tenia serrata, the number and age of
which I knew beforehand, since I had myself planted them,
there were found in the intestines of one of the dogs
some individuals of the Tznia cucumerina. My dogs had
taken nothing but milk, and cysticerci pisiformes. Were
there cysticerci of different kinds in the peritoneum of
the rabbit? The veil is now withdrawn. We have just
said that the dog harbours a tick known under the name
of Trichodectes, and in this trichodectes lodges the
Scolex, we might even say the larva of the Tenia
cucumerina. Dogs, especially young ones, lick their
hair continually, and it is by this operation that the
young tenia is introduced. It is by a similar process
that the horse introduces the eggs of the Cistrus which
are hatched in its stomach.

Many of these ticks live abundantly in birds, and
multiply rapidly. The Liothe pallidum lives on the cock,
the Liothe straminewm on the turkey, the Philopterus
falciformis on the peacock, the Philopterus claviyormis on
the pigeon. It is to be observed that every bird can
nourish many different kinds. Fig. 2 represents the tick
which infests the sea-eagle, called Pygarg.

5

72 ANIMAL PARASITES AND MESSMATES.

Fishes harbour crustaceans
instead of ticks, and their-num-
ber is not less considerable than
on mammals and birds. These
crustaceans have perplexed na-
turalists more than once, be-
cause they could only regard them
as parasites. They live on the
produce of cutaneous secretions,
and if they improve, as do the
ticks, the cleanliness of their host,
they are not less useful in a
hygienic point of view, for they
“45 prevent the accumulation of cuta-
Fig. 2—Ricinus of the a neous productions.

Among these crustaceans, we
must mention the Caligi and the Arguli, which never
become bloated, the Ancei, and probably other genera.
Instead of the ungainly and unusual forms of true
parasites, they all preserve, together with their fishing
tackle and locomotive apparatus, their neat and elegant
appearance. The sexes even differ only in size. They
remain during the whole of their life what they are at
the beginning ; that is to say, charming in form, with a
delicately-shaped corselet, numerous and slender claws,
and are as graceful in their movements as when in a
state of rest. The greater number of osseous fishes lodge
Caligi on the surface of their skin. These fix themselves
by means of strong cables, but without sacrificing their
liberty. They are usually called fish lice.

Fishermen, when returning from the northern
fishery, generally find their vivarium full of these

MUTUALISTS.

graceful vermin. .It may be said
that the caligi are common every-
where, and that each species has
its own caligi. The fishes of
the family Plagiostoma, notwith-
standing the hardness of their
skin, afford food to some of these ;

they multiply so rapidly some-
times, that they cover their host
as though they took the place of
scales. The cod gives lodging to
a charming species of a very
beautiful shape, which in its turn,
affords a resting-place to the
Udonella. It is always attached
to the ovisacs, and doubtless plays
the same part as the Histriobdelle,
so that we shall find the Caligi
attending to the toilet of the cod,
and the Udonelle in their turn
waiting on the Caligi.

The name Arguli has been
given to some crustaceans which
resemble the caligi in size and in
manner of life, and which prin-
cipally frequent fresh-water fishes.
The Argulus foliaceus is the name
of the species which has
been known for the longest
time, and which is most
extensively found. It is to
be seen on our pikes, carps,

Of the natural

size.

Caligulus
(fem.)

elegans

74 ANIMAL PARASITES AND MESSMATES.

sticklebacks, and on the greater part of our river fish.
Mr. Thorell, in his monograph, mentions twelve species
of Arguli proper, and four species of which he com-
posed the genus Gyropeltis. Four are found in Europe, two
of which are on salt-water, and two on fresh-water fish.

Quite recently, Professor Leydig has made known
another species living on the Phoxinus levis. Arguli are
met with on the fishes of Africa, the Indies, and North
and South America. Like the caligi, these animals
spontaneously abandon one host, to go and attend to
the toilet of another.

Another animal, which has been taken for a Lernean,
deserves to take its place by the side of the Caligi, at
least on account of its manner of life. We refer to that
singular being which Leydig discovered in 1850 in Italy,
while studying the mucous canal of a Corvina, at
Cagliari, and to which he gave the name of Spherosoma.
To judge by the plate and by some details, this
Spherosoma, the name of which ought to be changed to
Leydigia, belongs, if we mistake not, to the same group
as the Histriobdelle. We are persuaded that the first
opportunity will confirm the correctness of this alliance,
by the study of its embryonic form. If we had not been
able to examine into all the development of the Histrio-
bdelle, more than one naturalist would have considered
them Lernzans, as happened at the congress of German
naturalists at Carlsruhe.

If we see many of these crustaceans live a joyous life
while young, there are others which seem to practise
economy, and to emancipate themselves when they have
grown old. Mons. Hesse and Mr. Spence Bate a few
years since revealed the secrets of their existence.

MUTUALISTS. 15

Naturalists had recognized some crustaceans under
the name of Ancei, and others under the name of
Pranize, living together upon fishes, but with very
different organs for fishing and swimming. M. Hesse,
curious to know the manner of life of the Pranize, made
observations on them in a small aquarium, and he per-
ceived that the parts of the mouth were all at once
transformed into formidable mandibles, which caused
them to resemble Ancei. As it had often occurred with
respect to other groups, that the same crustacean at
different periods of its evolution had been taken for
different animals, the naturalist of Brest had some sus-
picion as to their identity, and soon ascertained by direct
observation that he had not been mistaken. The Pranize
become Ancei, and live upon fishes under their first
form, like caligi and arguli. Nothing can be seen
which is more curious than these crustaceans, which
ride on the back or the sides of fishes, and assume there
every possible attitude.

The Pranize fix themselves in the mouth and in the
gills as well as on the skin. Some are found on
sharks as well as on osseous fishes. They fear neither
heat nor light, and do very well under damp sea-weed
while waiting for the return of the tide. They run and
swim with the same facility. When in the condition of
Ancei, they lose their agility, and, under this form, all
denotes their sedentary habits. They appear to live in
holes, at the bottom of which they defend themselves
with their powerful mandibles. It has been observed
that fecundation is accomplished, as in the Azolotls,
before the evolution is: complete, but that the eggs are
not laid until the animal assumes the form of Anceus.

76 ANIMAL PARASITES AND MESSMATES.

‘We may here remark that the change of appearance
takes place only among the females; the males preserve
their dress and their liberty. Some naturalists assert
that we must not accept the metamorphosis of either
sex as an established fact, except for the purpose of
arrangement. All, however, tends to show that Mons.
Hesse has fairly interpreted facts; but it appears to us
probable that the whole of the history of these strange’
crustaceans is not fully known.

Fishermen have long since known whale-lice,. the
Cyami of naturalists, of which we have already made
mention while speaking of free messmates. They live
at liberty on the skin of their host, and multiply with
extreme rapidity. These Cyami have a regular form,
but completely different from the others, and have given
(like the Ricini and the afore-mentioned crustaceans),
great trouble to systematic zoologists. The place which
they ought to occupy is far from being definitely fixed.
At all events they may be considered as a shorter kind
of Caprelle.

As each whale has cirrhipedes which are peculiar to
itself, so each has its own cyami. Professor Litken, of
Copenhagen, has made known ten or twelve species, all
found on cetacea, in the two hemispheres. The sup-
posed Cyamus, represented by Dr. Monedero as living
on the Biscayan whale, is a Pyenogonon.

The Anilocre and the Nerocilw, like the Cyami
and other genera, establish themselves on the back of a
fish which is a good swimmer. Jealous of their liberty,
they preserve their oars and their fins, in order to
change their convoy, when the desire seizes on them,
and do not imitate the Bopyrians, which instal them-

MUTUALISTS. 17

selves onthe narrow branchial cavity of some decapod
crustacean, and as soon as they have entered, throw oft
all their travelling baggage; in fact, there is no other
means for them to gain admission ; their lot is identified
with that of their host; they can no longer live without
him. The female only, it is true, thus renounces her
liberty ; she sacrifices herself, as usual, for her family,
while the male, far from giving himself up, preserves his
defensive arms, his claws, and his liberty.

The crustaceans called Caprelle are perhaps not so
independent as they appear to be; it is not impossible
that their place may be among the crustaceans now
under our consideration. They are often found, together
with the Tanais, on the bodies of cetaceans and chelo-
nians, on plagiostomous fishes, or in the midst of
colonies of Sertularie. They also establish themselves
on buoys when they are well covered with animal life;
and we have discovered them in prodigious numbers on
a piece of cable which had lain at the bottom of the sea,
and the whole surface of which was covered with animals
of every kind.

We may here mention the Pycnogonons, the Saphy-
rine, the Peltidizw, and the Hersilie; these crustaceans
often crawl over the skins of their congeners, but without
ever renouncing their independence; and they are all
more or less occupied with the toilet of their neighbours.

We shall place in a second section some animals
which have been usually classed among parasites,
rather because of their living upon their neighbours
than on account of their mode of life. If it is necessary
in menageries to have keepers to cleanse the animals
themselves, it is as requisite to have others to keep the

78 ANIMAL PARASITES AND MESSMATES.

cages clean, and to remove dung and filth. Many
animals perform this office. The rectum of frogs is
always literally full of Opaline which swarm in this
cavity, like ants in their ant-hill, and doubtless live on
the contents of the intestine.

These Opaline are true infusoria, which do not wait
till the fecal matters are decomposed, and till the waters
are corrupted by their presence; they prevent accidents
which might arise, and interfere in time to purify the
water from these excretions. There have been found
hitherto in the rectum of frogs, and in the different
annelids, the Pachydrili, the Clitelides, the Lumbriculi,
and the Enechytrei. We have also seen them in the
Planaria and the Nemertians. There is no sight more
curious for those who are commencing microscopical
studies, than the examination of the contents of the
rectum of these Batrachians. Van Leeuwenhoeck knew,
two hundred years ago, those animalcule, to which
Bloch at a later period gave the name of Chaos intesti-
nalis, There are also some Rotatoria, the Albertie for
example, which ought to have a place here, and which
Dujardin has described and named. They live in the
intestines of the Lumbrici and of snails, and in the
larve of Ephemerides.

Dujardin first pointed out the Albertia vermiculus ;
since then Mons, Schultze has made known the Albertia
of the Ndis littoralis, and Radkewitz has recognized in
the small worm of our gardens the Enchytreus vermicu-
laris. Long since, Siebold correctly stated that these
animals are not parasites, since they do not live at the
expense of their host,

There is a worm in the Philippine Islands, as Pro-

-

MUTUALISTS. 79

fessor Semper has informed me, which lodges in the
intestines of a fish, with its head usually projecting
outwards, and which watches the crustaceans attracted
by the excreta of its host; but although it chooses the
intestine of its neighbour as a place of shelter, it is not
@ parasite.

Fishermen affirm, and the examination of the
animal’s stomach confirms their assertion, that the
Cyclopterus lumpus feeds on nothing but the excreta of
other fishes. Indeed, it is not possible to count the
number of intestinal worms known by the name of
Scolex, which are found in the contents of the stomach
and the intestines. Besides this, we have long known
the peculiarities of some insects which cannot live
except on the dung of certain animals; and there is an
example of one of these insects, found in a fossil state,
which anticipated the discovery of the remains of
an extinct mammal before unknown in that district.
The larve of the fly Scatophaga stercoraria live only on
excrementary matter.

There are also nematode worms which exist under
these conditions, and which develop and propagate their
species in the intestines as if in the midst of damp earth.
The small eel-like creatures so abundant in cow-dung
propagate in it; they are not parasites, and are allied to
those of which we speak in this chapter.

Besides those attendants which busy themselves
about the cleanliness of other animals, we find some
whose duties are less extensive, and whose cares are
more limited. Many animals produce a greater number
of eggs than they can bring to perfection, and those
which are decomposed for want of fecundation, or which

80 ANIMAL PARASITES AND MESSMATES.

die in the course of evolution, are under the care of
an especial attendant, employed to make away from
time to time with the addled eggs, or the embryos that
have failed to come to maturity.

In this manner lobsters give lodgings in the midst of
their eggs to a worm, which we at first took for a Ser-
pula, and which, after a complete examination, turns out
to be one of the Hirudinide : we have given it the name
of Histriobdella. It is as singular in its movements as
in its conformation, and its manner of living approaches
that of the Pontobdelle of the rays, of which we shall
speak subsequently. We announced this discovery a few
years. ago in the following terms :—

It is known that lobsters, as well as crabs and the
greater part of the crustacea, carry their eggs under the
abdomen, and that these eggs remain suspended there
till the embryos are hatched. In the midst of them lives
an animal of extreme agility, which is perhaps the most
extraordinary being which has been subjected to the eyes
of a zoologist. It may be said, without exaggeration,
that it is a biped, or even quadruped, worm. Let us
imagine a clown from the circus, with his limbs as far
dislocated as possible, we might even say entirely de-
prived of bones, displaying tricks of strength and activity
on a heap of monster cannon balls, which he struggles
to surmount; placing one foot formed like an air-
bladder on one ball, the other foot on another, alter-
nately balancing and extending his body, folding his
limbs on each other, or bending his body upwards like
a caterpillar of the geometride, and we shall then have
but an imperfect idea of all the attitudes which it
assumes, and which it varies incessantly.

MUTUALISTS» 81

Its rank and its affinities would have given rise to
long discussions if we had not made known at the same
time its evolution and anatomical structure.

It is neither a parasite nor a messmate; it does not
live at the expense of the lobster, but on one of the pro-
ductions of these crustaceans, much in the same manner
as do the Caligi and the Arguli. The lobster gives him
a berth, and the passenger feeds himself at the expense
of the cargo; that is to say, he eats the eggs and the
embryos which die, and the decomposition of which
might be fatal to his host and his progeny. These
Histriobdelle have the same duty to perform as vultures
and jackals, which clear the plains of carcases. That
which causes us to suppose that such is their appro-
priate office, is that they have an apparatus for the
purpose of sucking eggs, and that we have not found in
their digestive canal any remains which resemble any
true organism. We find the feces, rolled up as balls,
placed after each other in their intestines.

The crustaceans also feed other Hirudinide. Mons.
Leydig has noticed a M; yzobdella on the Lupa diacantha.
The fresh-water crab, common in all the rivers oc
Europe, nourishes two, the Astacobdella reselii, which
lives under the abdomen, or about the eyes, and the
Astacobdella Abildgardi which especially frequents the
branchie. Two astacobdelle on the same crab doubt-
less play different parts. We should almost venture to
assert, & priori, that the species in the gills lives as a
parasite on the blood of its host, whilst the other, lodged
under the abdomen, plays the same part as the histrio-
bdella of the lobster.

We often find among the eggs of the or ee crab of

t

32 ANIMAL PARASITES AND MESSMATES.

our coasts (Cancer menas) a nemertian which probably
performs the same office. He is lodged while young in
a kind of firm sheath attached to the abdominal pro-
cesses. We have been able easily to study the first
phases of its evolution. We have given it the name of
Polia involuta. ,

This nemertian had been observed at Messina, and
described before by Kolliker under the name of Nemertes
carcinophilus, and it has just been described and figured
anew by Mr. M‘Intosh, in a monograph of British an-
nelids published by the Ray Society.

The sturgeon seems to give lodging in its eggs to a
polyp which plays the same part. In fact, Mons. Ows-
jannikoff, at the congress of Russian naturalists at Kiew,
described an animal, Accipenser ruthenus, which lives in
the eggs of the sterlet. Some eggs placed in water for a
few hours at first show tentacles on the outside, then a
whole colony, and each part consists of four individuals,
which have a common digestive cavity, resembling some-
what a hydra divided longitudinally in four. Hach has
six tentacles, two of which are terminated by transparent
corpuscles, perhaps nematocysts ; the digestive cavity
extends into the arms, as in the hydra; the mouth is
not between the tentacles, but at the opposite pole.
They are not all lodged within the eggs; some are found
outside, according to the observations of Mons. Koch.
Does not this animal fulfil in the egg of the sterlet,
the same office as the histriobdella in the egg of the
lobster ?

The eggs of some insects are attacked by very little
ichneumons, the Proctotrupide ; they empty them, and
then instal themselves in the shell. Mons. Fabre has

MUTUALISTS. 83

mentioned, in his memoir on the habits of the Meloé, a
worm found in an egg.

M. Barthelemy has studied a nematode worm (Asca-
roides limacis) which inhabits as a parasite the ege of the
grey snail; is this not the ordinary worm of the snail
which has introduced itself into the eggs ?

Many animals establish themselves on their neigh-
bours, not to obtain any advantage from them, except to
profit by their fins; they are not themselves sufficiently
adapted to rapid motion, so they seize a good courser,
mount on his back, and ask from him only a resting-
place and no provisions. But it is often very difficult
to say where commensalism ends and mutualism
begins; the cirrhipedes, for example, establish them-
selves on a piece of floating wood, or on the bottom of a
vessel; on a. block of stone, or on one of the piles of a
groin; on an immovable animal as well as on a good
swimmer.

Some fourteen years ago, Jacobson of Copenhagen
wrote an interesting essay, to show that the young
bivalves that are found inthe branchie of anodonts at a
certain period of the year are parasitical animals, for
which he proposed a new name. But these supposed
parasites are only young anodonts, which by the help of
a very long cable, which proceeds: from their foot like a
byssus, attach themselves to their mother, or to a fish
which will carry them to.a distance.

We see full-grown acephalous molluscs, as mussels
and pinnae, still keep these cables, under the name of
byssus, during their whole life. There are also among
distomians, worms which though they are hermaphro-
dite, couple two and two, and have this additional pecu-

84 ANIMAL PARASITES AND MESSMATES.

liarity, that while one increases rapidly the other be-
comes atrophied.

An Egyptian distome, which lives in man, gives an
instance of this peculiarity, as well as the D. /filicolle,
which inhabits a fish (Brama Raii). The caligi which
live on the skin of fishes are, when young, fastened by a
cord which comes from the anterior edge of their cara-
pace: while quite little, they put themselves under. the
protection of a kind neighbour, and allow themselves to
be led by him.

The new tubularia, which we have dedicated to our
learned colleague Dumortier, often fixes itself on the
carapace of ordinary crabs, and causes itself to be con-
veyed like the Hcheneis; the tubulary observed by
Gwyn Jefireys, close by the eye of the Rossia papillifera,
a cephalopod mollusc, perhaps belongs to the same
species.

Every colony of campanularie or sertularie lodges a
crowd of messmates and mutualists; and there are a
great number of crustaceans and polyps of all sizes
which serve as an abode for infusoria of every kind.
Some establish themselves on the carapace or on the
swimming appendages, as in a carriage; others on one
of the gills, which renders their mode of life more eagy,
and the danger less great. An amphipod very exten-
sively spread over our sea-coasts, the Gammarus marinus,

usually has its appendages covered with Vayinicola
cerystallina. :

CHAPTER V.
PARASITES.

“En plongeant si bas dans la vie, je croyais y rencontrer les fatalités
physiques, et j’y trouve la justice, ’immortalité, ’espérance.”—MIcHELET,
VInsecte.

Tar parasite is he whose profession it is to live at the
expense of his neighbour, and whose only employment
consists in taking advantage of him, but prudently, so
as not to endanger his life. He is a pauper who needs
help, lest he should die on the public highway, but who
practises the precept—not to kill the fowl in order to get
the eggs. It is at once seen that he is essentially
different from the messmate who is simply a companion
at table. The beast of prey kills its victim in order to
feed upon his flesh, the parasite does not kill; on the
contrary he profits by all the advantages enjoyed by
the host on whom he thrusts his presence.

The limits which separate the animals of prey from
the parasite are usually very clearly marked; jet the
larva of the ichneumon, which eats its nurse, piece
after piece, resembles a carnivorous animal as much as
a parasite. There are indeed certain animals which
take advantage of the good condition of their Amphi-

86 ANIMAL PARASITES AND MESSMATES.

“tryon, but which render to him in return precious
services. Thus those which live on the produce of the
secretions, or which clear the system of useless ma-
terials in exchange for the hospitality which they receive,
are not true parasites. These services are of a very
different character, and the duties which they some-
times perform for each other are in some respects ana-
logous to medical care.

Every animal has its own parasites, which always
come from without. With some few exceptions, they
are introduced by means of food or drink. In order to
ascertain their origin, the naturalist must beforehand
study the food, that is to say, the prey or the plant
which furnishes the habitual nourishment of the host
which gives them shelter.

A carnivorous animal, however, does not in general
content himself with a single kind of prey—one yora-
cious animal of this class devours all that comes in its
way; another, more of an epicure than a glutton, chooses
with more discernment. But in the midst of this varied
kind of food there is always some species which forms
the staple of the usual bill of fare, and it is necessary to
find out what this is if we wish to ascertain the parent-
age and the metamorphoses of the parasite, since it is
that which conducts the parasite to its new destination.
The mouse is destined to the cat, and the rabbit to the
dog; in the same manner, each one of the herbivora is
intended to be the prey of a carnivorous animal, if not
larger and stronger than itself, at least more cunning.
It is of great importance to discover the animal which
conducts the new-comer into his habitation. When we
know it, we have only to introduce into it the stranger.

PARASITES. 87

guest, that sooner or later he may pass into the body of
his accustomed Amphitryon. In order thoroughly to
know these sedentary or vagabond populations, we
must not only study them at the different periods of
the year, and under all the conditions of their irregular
life, but it is necessary to follow them from the moment
that they quit the egg till their complete evolution,
closely noticing all that relates to their reproduction.

In the dung of the cow, by the side of the elegant
Pilobolus, live masses of small eels, born in the stomach
of the animal, which wind and twist like microscopical
serpents, and do not seek the slightest help from the
organ which shelters them. They are hatched in the in-
terior of the stomach, as if it took place in the meadow.
These little eels have evidently only the appearance
of parasites, and it may be that they render some
service in some of the organs through which they pass.
This may also be the case with those which live on the
feces of others, or which, lodged in the rectum, watch for
the prey which is attracted by the odour. These, espe-
cially the latter, are rather messmates than parasites.
True parasites are animals entirely dependent on
their neighbours, unable to provide for themselves, fed
entirely at the expense of others. It is generally sup-
posed that parasites are exceptional beings, requiring a
place by themselves in the animal hierarchy, and know-
ing nothing of the world except the organ which shelters
them. This is an error. There are few animals, how-
ever sedentary they may be, which are not wanderers at
some period of their lives, and it is not even uncommon
to find some which live alternately as noblemen or
as beggars. Many of them only deserve to be placed

88 ANIMAL PARASITES AND MESSMATES.

among paupers when they are in their infancy or at the
approach of adult age, for they only seek for help at
the beginning or towards the end of their career. These
are very numerous, and more than one species change
their dress so completely that they can no longer be
recognized. Finding with their host both food and
lodging, they throw off their fishing and travelling gear,
settle themselves comfortably in the organs which they
have chosen, and having got rid of the baggage which
connected them with the outer world, preserve only their
sexual organs.

As to the rank which these parasites occupy in the
seale of being, it may be said that there is no especial
class of parasites; and worms are not distinguished in
this respect, except by having a greater number of species
subject to this rule. All classes among invertebrate
animals include parasites.

It is also an error to suppose that the whole species,
the young as well as the old, the males as well as the
females, are always parasites; often the female, not being
able to provide for the necessities of life, seeks for food
and shelter, while the male continues his nomad life.
Therefore the female alone puts on the pauper’s dress, and
by a recurrent development, assumes sometimes such
a singular appearance that the male no longer resembles
her. One cannot say that the females constitute the
beau sexe in this group, since they are often so monstrous
in form and size that their appearance has nothing in
common with a perfect animal; their body is deprived oi
all its exterior organs, and there often remains only a
skin in the form of a leather bag, without any distin-
guishing character. j

PARASITES. 89

What is still more astonishing, is to meet with males

which, under the conditions to which we have just
“alluded, come at last to seek for assistance from their
own female, so that she has to provide for all; and the
charitable animal which comes to her help takes the
whole family under his charge. Assistance is thus
thoroughly organized in the lower world; neighbours are
found which serve as a créche for the indigent when they
first quit the egg, others as a hospital for the infirm
adults or the females, and others again play the part of
innkeepers for all, instead of affording a place of refuge
for some privileged individuals.

There are but few animals, if indeed there are any,
which have not their peculiar parasites. Of all the fishes
of our coasts we have never found but one which had
none; and perhaps, could we observe this fish in different
latitudes, we might find that it had its poor dependants
as well as the rest.

Thus we may assume that no animal is free in this
respect, and man himself regularly affords hospitality to
many of them. We feed some with our blood and our
flesh; there are some which lodge on the surface of our
skin, others in the interior of our organs; some prefer to
establish themselves on children, others on adults. The
name alone of some is sufficient to make us shudder,
while others live peaceably in some crypt, without our
suspecting their presence. Who is there that does not
nourish some acari, of the genus Simonea, in the mem-
brane of the nose? In fact, man gives a home to some
dozens of parasites, and the presence of the most terrible
among them constitutes, in certain countries, a condition
of health which is envied. The Abyssinians do not

90 ANIMAL PARASITES AND MESSMATES.

consider themselves in good health, except when they
nourish one or many tape-worms.

Among the animals to which man gives his involun-
tary assistance, we may mention first, four different
Cestoidea, or tape-worms, which live in the intestines ;
three or four Distoma, which lodge in the liver, the intes-
tines, or ‘the blood; nine or ten Nematodes, which inhabit
the digestive passages or the flesh. There are alsosome
young Cestodes, named Cysticerci, Echinococci, Hy-
datids, or Acephalocysts, which find in him a créche to
shelter them during their life. These always choose
enclosed organs, like the eye-ball, the lobes of the brain,
the heart, or the connective tissue. We also provide a
living for three or four kinds of lice, for a bug, for a
flea, and two ascarides, without mentioning ~ certain
inferior organisms which lurk in the tartar of the teeth,
or in the secretions of the mucous membrane.

There are some animals which harbour few inhabi-
tants, while there are others that keep up a great retinue;
and it is not always, as we have already said, that those
who give lodging to but few enjoy the most excellent
health. We might give as an instance of this, a fish
which is known to all, the turbot, which as well as the
woodcock is highly prized, though both have their in-
_testines literally obstructed by tape-worms and their
eggs. We have never opened one, large or small, lean
or fat, which had not its intestines filled with cestode
worms. They are so numerous as to form a kind of
cork, which one might think intended to close the pas-
sage of the pylorus.

Some authors give remarkable instances of the abun-
dance of parasites. Nathusius speaks of a black stork,

PARASITES. 91

which lodged twenty-four Filarie lobate in its lungs,
sixteen Syngami tracheales in the tracheal artery, besides
more than a hundred Spiroptere alate within the mem-
branes of the stomach, several hundreds of the Holosto-
mum excavatum in the smaller intestine, a hundred of
the Distoma ferox in the large intestine, twenty-two of
the Distoma hians in the csophagus, and a Distoma
echinatum in the small intestine. In spite of this affluence
of lodgers the bird did not appear to be in the least
inconvenienced.

Krause, of Belgrade, mentions a horse two years
old, which contained more than five hundred Ascarides
megalocephale, one hundred and ninety Oxyures curvule,
two hundred and fourteen Strongyli armati, several mil-
lions of Strongyli tetracanthi, sixty-nine Teniz per-
foliatz, two hundred and eighty-seven Filaria# papillose,
and six Cysticerci. When we consider how many eggs a
single worm produces, we can understand how it is that
so few animals escape being invaded by them.

Sixty millions of eggs have been counted in a single
nematode, and in a single tape-worm, or rather in a
colony, even a thousand millions of eggs. Even the,
very animals which live as parasites, harbour others in
their turn. We find parasites on parasites, as we find
messmates upon messmates. Almost all writers on this
subject give examples of these; some in the larve of
ichneumons, others in the lerneans, and we have more
than once met with nematodes in different crustacea still
attached to their host.

In order to understand thoroughly the living furni-
ture of an animal, especially of a fish, it is necessary to
examine it while young; the feces are the Kitchen-mid-

92 ANIMAL PARASITES AND MESSMATES.

dings of the stomach ; it is from them that we can appre-
ciate the bill of fare of each. This study of the food will
one day excite much interest, not only in a scientific
point of view, but also with reference to fishing as an
occupation.

There are some animals which are infested at every
period of their life, and at every season ; others in far
greater number only during their youth, and they gather
in at the commencement of their life the harvest for the
rest of their days. The greater part of parasites, espe-
cially of fish, are introduced with the first nourishment.
As soon as they issue from the egg, young rays, like
young turbots, are already stuffed with worms which
afterward obstruct the digestive organs. The stomach of
each of these fishes is like a filter which allows every
thing which is food to pass, but detains on its passage
and without any change all that is living. When we
examine the stomach and observe the food in its different
degrees of digestion, we see distinctly the worms coming
out of their holes, wallowing in that which physiologists
call chyle, and choosing afterwards at their convenience
the place where they may completely develop themselves.
At the end of a few days, the fish may have swallowed an
innumerable quantity of small animals, and if each of
them introduces some worms, we can easily understand in
how short a time the intestine becomes literally filled.

There is no organ which is sheltered from the in-
vasion of parasites: neither the brain, the ear, the eye,
the heart, the blood, the lungs, the spinal marrow, the
nerves, the muscles, or even the bones. Cysticerci have
‘been found in the interior of the lobes of the brain, in
the eye-ball, in the heart, and in the substance of the

PARASITES. ~* 93

bones, as well as in the spinal marrow. Each kind of
worm has also its favourite place, and if it has not the
chance of getting there, in order to undergo its changes,
it will perish rather than emigrate to a situation which
is not peculiar to it. One kind of worm inhabits the
digestive passages, some at the entrance, others at the
place of exit; another occupies the fosse of the nose;
a third the liver, or the kidneys.

We may even divide parasites into two great cate-
gories, according to the organs which they choose:
those which inhabit a temporary host, almost always
instal themselves in a closed organ—in the muscles, the
heart, or the lobes of the brain; those, on the contrary,
which have arrived at their destination, and which,
unlike the preceding, have a family, occupy the
stomach with its dependencies, the digestive passages,
the lungs, the nasal fosse, the kidneys, in a word,
all the organs which are in direct communication with
the exterior, in order to leave a place of issue for their
progeny. The young ones are never enclosed. Even
the blood is not free from these animals, but there
are few which lodge there, except during the act of
migration. ‘

In Egypt, Dr. Bilharz observed a distome in the
blood of a man (Distoma hematobium) ; the Strongylus
of the horse has been long known, which causes serious
injuries in its vessels (Strongylus armatus) ; as also the
strongylus of the dolphin and of the porpoise (Strongylus
inflexus), and the filaria of the dog (Filaria papillosa) ;
and some are also found in the blood of many birds,
of reptiles, batrachians, and fishes; so that there is no
class of vertebrates which escapes.

x

94 ANIMAL PARASITES AND MESSMATES.

There are some which, like leeches, seek assistance
from their neighbours, but are content to snatch their
food as they pass, and only attach themselves for a
short time to the host which they despoil; they retain
their fishing or hunting tackle, as well as their organs of
locomotion. These parasites, which never take up their
lodging on the host which nourishes them, have no
sooner sucked his blood, or devoured his flesh, than they
resume their independent life.

They do not disfigure themselves, nor put on any
special costume, like those which seek a permanent
abode. Gluttony is not with them the only moving
principle of existence; they do not forget what they owe
to the world, and keep up an appearance which allows
them at all times to present themselves afresh.

Parasites are scattered over every region of the
globe; they choose their place, and observe, like all
living creatures, the laws of geographical distribution.
All do not inhabit the animal kingdom; some seek for
assistance in vegetable life. Many insects lay their eggs
in seeds or fruits, and their progeny, as soon as they
are hatched, find abundant nourishment in the sap or
in the farina stored up for the young plant; others
pass into a state of lethargy while the seed is dry,
and recover their activity every time that they receive a
little humidity.

The female of a coleopterous insect deposits its eggs
in the nut, and in proportion as this grows, the young
larva devours the kernel. When it is brought to table,
it encloses only the skin and the excretions of the larva.
A weevil establishes itself in a similar manner in cereal
plants, and, small as it is, it may produce great calamity

PARASITES. 95

by multiplying in granaries. There are even worms
which lodge in certain of the graminacex, and get com-
pletely dry with the envelope which contains them,
without ceasing to live. Their life is suspended till the
day when the seed is sufficiently softened in the earth or
the water.

We have seen that each parasite has its host: we
must have a particular name to designate it. But that
does not imply that if it find not its dwelling-place it
must perish. It may only live some time at the
expense of its neighbour, and thus pass for its parasite.
Naturalists are occasionally deceived. Thus, they once
believed in the passage of the Schistocephalus of the
stickleback into the intestines of certain birds which
eat them, and in which they are only found accidentally.
The Ligule of the Cyprinide, found in the intestines of
the cormorant or the goosander, are not, in our opinion at
least, worms peculiar to these birds. They are strangers
which must either emigrate again or die. Acari which
originally belonged to mammals and birds, have been
found living on man, causing prurigo, or even serious
maladies, and yet these parasites are not regarded as
peculiar to our species. We might cite other examples.
Who has not been annoyed by the flea, which abandons
for an instant the dog, its natural host ?

Among these free parasites, many do not attach
themselves to a particular species, and well deserve
the title of cosmopolitan parasites. Thus we see
that the Ascaris lumbricoides, so common among child-
ren, lodges also in the ox, or the horse, the ass, and
the pig. The Distoma hepaticum, which is a parasite
pecutiar to the sheep if we may judge by its abundance

96 ANIMAL PARASITES AND MESSMATES.

in this animal, may find its way into the liver of man,
or into that of the hare, the rabbit, the horse, the
squirrel, the ass, the pig, the ox, the stag, the roebuck,
and different species of antelope. It is to be remarked
that all these animals have a vegetable regimen. By
drinking the water which contains the cercaria of this
species, they grow infested by this singular lodger. The
large Echinorhyncus (EZ. Gigas) has been found in the
dog, and the pig, perhaps in the phocine ; and instances
are mentioned in which it has even migrated into man:
The Gordius aquaticus appears to live and develop itself
in different species of insects; and among the articulated
parasites, we meet with the Ixodes ricinus, commonly
called the tick, on the dog, the sheep, the roebuck, and
the hedgehog ; and instances are given of its presence
on man. It has been long since proved in menageries
and zoological gardens, that the Acarus of the camel is
able to give a cutaneous disease to man.

As we have before said, there are many parasites
which require to be studied in order to determine the
host peculiar to each of them; although parasites
sometimes lose their way, and introduce themselves into
the wrong neighbour, yet they can live there but a short
time. Instances have been known, in which the larvee
of flies have penetrated into man accidentally by the
mouth’ or the nostrils. Reptiles have been known to
live a certain time in the stomach. A German physio-.
logist, Berthold, professor at the University of Gottingen,
has given an account of all those which have been
found under such circumstances, and the number of
them is considerable; he has written a memoir on the
abode of living reptiles in man,

PARASITES. 97

Among other instances, this naturalist mentions the
case of a boy of twelve years of age, who, in 1699, after
suffering acute pain, voided from the intestines nearly
one hundred and sixty four millipedes, four scolopendra,
two living butterflies, two worm-like ants, thirty-two
brown caterpillars of different sizes, and a coleopterous
insect. These animals lived from three to twelve days.
This is not all: the same child, two months afterwards,
voided four frogs, then several toads, and twenty-one
lizards, and sometimes a live serpent was seen for a
moment at the bottom of his mouth. Happily for
science, we do not see such things seriously related in
books at the present day.

The size of parasites is very various: Boerhaave
mentions a bothriocephalus three hundred ells in
length; at the Academy of Copenhagen, it was reported
that a solitary tape-worm (Tenia solium) had been
found eight hundred ells long. Female strongyli have
been seen from two decimétres to one metre in length;
and Gordit of two hundred and seventy millimétres.
We have found in a fish a worm which lived rolled up
like a ball, and which measured, when unrolled, more
than a métre.

Parasites present an extraordinary variety of forms,
and the differences between the sexes in size as well
ag in appearance are greater than in any other group
of animals. The male of the Uropitrus paradoxus, the
Urubu of Brazil, has the usual form of a round long
worm, while the female resembles a ball of cotton, without
the slightest analogy with the other worms of the order.
The Lerneans also have females excessively various in
size and appearance, while the males generally resemble

98 ANIMAL PARASITES AND MESSMATES.

each other in their external characters. What is not
less remarkable is, that hermaphrodite worms often
unite in couples, and that only one of the two seems to
perform the function of a female, and increases in size
(Distoma Okenii, Bilharizia). It even happens that the
union is so complete that the species appears formed of
two individuals fastened to each other. The Diplozoa
show us @ curious example of this. The gills of breams
are usually infested by these last-mentioned worms.
Nothing is more strange than to see all these individuals
united two and two as if soldered together, each pre-
serving its mouth and digestive canal, and. producing
eggs which give birth to isolated individuals. We some-
times see males so completely absorbed in their females,
even in an anatomical point of view, that they only
represent a fragmentary apparatus. The male of the
Syngami is so obliterated, that when compared with the
other males of its order it is only a testicle living on
the female.

- Should an organ infested with worms be considered
diseased, simply on account of their presence? We hesi-
tate not to say that, as long as these guests cause no
disorders, there is no pathological condition. The child
which has Ascarides lwmbricoides in- its stomach is not
necessarily ill. All animals in a wild state always
have their parasites; they lose them rapidly when in
captivity.

The Abyssinians do not take medicine when they
have tenie; on the contrary they are in a better state
of health. Do we not find medical men prescribing the
employment of leeches, and consequently calling in the
assistance of certain parasitical animals? This action,

PARASITES. 99

far from being a cause of sickness, is in this instance
a remedy, and no one can foresee all that science has
a right to expect from the salutary effects of certain
parasitical worms on the system. There are, if we
mistake not, many discoveries in store for observers
in this order of investigation.

But here, as in all things, excess is hurtful. Certain
organisms, developing themselves immoderately, may
break the harmony necessary between the parasites
and the host which they frequent. It has been found
recently that many morbid affections, as the potato
and vine diseases, have for their origin only the

abnormal development of certain microscopic beings
hidden in the organism.

It is found, that in Egypt, a aaies is developed
in the blood, and occasions a very severe malady,
scarcely known to physicians. In Iceland, a cestode
causes the death of a third part of the population.
Worms develop themselves in the eye, and may even
cause blindness; the Canuwrus of the sheep causes giddi-
ness, and becomes fatal to the animal which harbours it.
The chlorosis observed in Egypt and Brazil must, it
appears, be, attributed to a considerable development of
a nematode worm, which lives in the small intestines,
and which naturalists know under the name of Dochmius
duodenalis ; and lately the Trichine set all Europe in a
state of excitement, and trichinosis was for a time more
dreaded than cholera. In spite of all these accidental
circumstances we think that the animal which possesses
its ordinary parasites, far from being ill, is in a normal
physiological condition.

When we consider these animal parasites in general,

100 ANIMAL PARASITES AND MESSMATES.

one would think that their tenacity of life is very feeble,
and that the slightest derangement would be sufficient
to kill them. It is not so; on the contrary, some of
them can be entirely dried up, and return to life every
time that they are moistened; and the eggs of some of
them resist the most violent reagents. We have known
eggs preserved for years in alcohol, in chromic acid, and
in other agents which destroy life everywhere else; and
then give birth to embryos directly they are placed in
pure water or damp earth.

Some years ago they had no idea of the migration
of animals from one body to another. As we have said
elsewhere, Abildgard, half a century ago, made experi-
ments on the worms of fishes which he caused ducks
to swallow, but these experiments had no result, and
formed rather an obstacle to ulterior progress, than an
approach to truth. The worms of fishes have been
known to live in birds; but these worms were only
there as adventitious parasites. Liguli live some days
in the goosander, but they do not maintain their position.

Our great initiator into the world of parasites, Mons.
Siebold, arrived also at a conclusion which could not
be maintained. Having observed, with his habitual
sagacity, that the cysticercus of the mouse is the same
worm which lives in the cat, he published his opinion
that the eggs of this tenia had lost their way in the
mouse, that the young worms had become sick there,
and that in the cat alone, they could be healthily and
completely developed. It was like a plant lost on a soil
where it could not live, and still less flourish. May I
be permitted to state by what means we have arrived
at the knowledge of the transmigration of worms ?

PARASITES. 101

I had commenced the study of encysted Tetrarhynchi
in the peritoneum of the Gadide in 1837. Ten years
afterwards, shortly after a visit from my learned friend,
Mons. Kolliker, I discovered that this world of parasites
did not live such a monotonous life as was supposed.
I ascertained by my dissections of fishes, that the
tetrarhynchi also, which were supposed to be disinherited
by Nature, knew how to vary their pleasures; that
instead of spending their whole life in a prison cell, they
change their home at a certain age, and pass the latter
part of their existence in more spacious habitations.

I had seen the Tetrarhynchus agamus inhabiting a
cyst in the peritoneum of the gadide, and I had met
with the same tetrarhynchus completely developed and
sexual in the spiral intestine of the voracious fishes
known under the name of squalide, or sharks. This
caused me to write to the Academy of Brussels, at the
meeting on January the 13th, 1849, that the order of
vesicular worms, admitted by all helminthologists, ought
to be suppressed.

These worms began to be understood when these
cysticerci ceased to be regarded as sick creatures.
Siebold had mistaken the eréche for the hospital, and
instead of seeing in the cysticercus a young animal full
of life and of the future, he looked upon it as a gouty
individual, ready to breathe its last sigh.

These fish had directed me in the right road; I had
closely followed up certain very characteristic worms,
which lived under a very simple form in certain fishes,
and which, passing with their host into the stomach of
another, finished in the latter their toilet and their
evolution. I had been a witness of all their changes

102 ANIMAL PARASITES AND MESSMATES.

of form from the cradle to the tomb, by following them
from fish to fish, or rather from stomach to stomach.
In fact these parasites are perpetually on their journey,
and constantly changing their host, and at the same
time their dress and mode of locomotion, so that
frequently, at the end of their voyage, they preserve
only shapeless rags to cover their eggs or their offspring.

That which adds still more to the difficulty of recog-
nizing them is, that while young they are often enveloped
in swaddling clothes which nevertheless permit them to
wander freely; then in a simple robe, in keeping with
the home which shelters them; and at last in a wedding
dress, which hides the. eggs and the apparatus which
produces them. The nymph in her virgin condition has
none of the attributes of future maternity.

It is in this category that we find the Distomes, so
common in all the classes of the animal kingdom. This
is not all: frequently, among these various forms, these
animals when young produce little ones, which in no
respects resemble the others, and are not even formed
im the same manner. As soon as they quit their swadd-
ling-clothes, they increase by gemmation, and without
sexual union, while those which are produced from buds
increase sexually. Thus the daughter does not resemble
her mother, but her grandmother. This phenomenon
has been known by the name of alternate generation;
we have called it digenesis.

But all parasites do not resemble those distomes,
which change several times both their host and their
costume. We find some of them, which the mother
deposits with care in the body of a neighbour, and which
pass all their early life in the viscera of an alien mother.

PARASITES. 103

Such are the Ichneumons, beautiful winged insects,
which perfidiously insert their eggs in the body of a
living caterpillar, whose internal part serves at the
same time for a cradle and for food. The young larva
devours organ after organ, beginning with the least im-
portant, till the last serves for the formation of the last
members of the winged insect.

More unfortunate are those which are kept under the
bolts and bars of their host from their early youth to
mature age; they have no participation in the great
banquet of life, except it be in the pleasures of the table
and of love. We also find some parasites which occupy
different organs in the same animal, and which have
different sexual attributes according to the situation
which they inhabit. We know some which are herma-
phrodite in the rectum or in damp earth, and whose
young ones, having the sexes separate, live as parasites
in the lungs.

Parasites are not usually reproductive in the animal
which they inhabit. They respect the hearth which
shelters them, and their progeny are not developed by
their side. The eggs are expelled with the feces, and
sown at a distance for other hosts.

Parasites may be divided into several categories.
We may bring together in the first of these, a certain
number of animals, which, without being true parasites,
seek for a place of shelter, and, either on account of their
wretchedness or thei misery, require this protection
in order that they may live.

In the second category, we may place those which
live at complete liberty, and only require for their sus-
tenance the superfluities of their neighbours; they take

104 ANIMAL PARASITES AND MESSMATES.

great care of the skin of their host, and use it sparingly.
Some also are found which cannot live without assist-
ance, but repay it with some service. Often, indeed,
they associate with their host, and live on a footing
of perfect equality with him; and besides these are
found associations in which equality is by no means
recognized, and where labourers or even slaves perform
the work disdained by their masters.

In the last category we shall arrange true parasites,
which take both their lodging and their food. And here,
again, we shall meet with three distinct subdivisions.

The first includes those which travel from one hotel
to another before they arrive at their destination ;
to-day they lodge in a prawn, to-morrow in a gudgeon,
then in some fish which preys upon others, as the perch
or the pike. These are nomadic parasites, which do not
stop or think of family life until they have found the
hotel for which they are destined.

Sometimes the parasite gets into a wrong train, and
not being able to retrace his steps, he remains at a
station where no other train will take him up. He is
condemned to die in a waiting-room.

In the last subdivision, we have parasites that have
arrived at their destination, occupying themselves in
future only with the joys of a family.

Thus we find some which are really at home, and
others which are on their journey, sometimes on the
right road, and at others, wandering and lost in an alien
“host.” The former are autochthonic parasites, the
others are foreigners. We may say that each animal
species has its proper parasites, which can live only in
animals which have at least more or less affinity with

PARASITES. 105

their pecular host. Thus the Ascaris mystax, the guest
of the domestic cat, lives in different species of Felis,
while the fox, so nearly resembling in appearance the
wolf and the dog, never entertains the Tenia serrata, 80
common in the latter animal.

The same host does not always harbour the same
worms in the different regions of the globe which it
inhabits. This relates both to the parasites of man, and
to those of the domestic animals. Thus the large tape-
worm ‘of man, which naturalists call Bothriocephalus,
is found only in Russia, Poland, and Switzerland. A
small tape-worm, Tenia nana, is observed nowhere
except in Abyssinia; the Anchylostoma is known at
present only in the south of Europe and the north of
Africa; the Filaria of Medina, in the west and the east
of Africa; the Bilharzia, that terrible worm, has only
been found in Egypt.

There are also parasitic insects dreaded by man, as
the Chigoe (Pulex penctrans) which, happily, is only
known in certain countries. Some, however, have
become cosmopolitan, since man has introduced them
wherever he has established himself.

Tho mammalia which live on vegetable diet have
Tenia without any crown of hooks, and man, according
to his teeth, ought only to nourish the Tenia medio-
canellata. We find in a work on the Algerian Tenia, by
Dr. Cauvet, that it is the Tenia inermis, that is to say,
without hooks, which is the species common in Algeria.
Among fourteen tenie which he had occasion to
examine, there was not a single Tenia solium. I have
said long since, that this species ought to be less widely
spread than the tenia without hooks. The Tenia solium

106 ANIMAL PARASITES AND MESSMATES.

comes from the cysticercus of the pig, the other from that
of the ox; and Dr. Cauvet has ascertained that the latter,
in the state of cysticercus, has already lost its crown.
We find extinct fossil genera and species in all the
classes of the organic‘world. Is it the same with worms
and animals of other classes which are only known in
the condition of parasites? Had the Ichthyosauri and
the Plesiosauri worms in their spiral ececum like plagio-
stomous fishes, which resemble them so much in the
digestive tube? We do not doubt this, and we should
have been glad to give some demonstration of it. For
this purpose, we have made a collection of the coprolites
of these animals, but we have not yet succeeded in
getting slices thin enough or sufficiently transparent to
discover the eggs or the hooks of their cestode worms.
Not long ago, the partisans of spontaneous genera-
tion found in the class of worms their principal argu-
ment for their old hypothesis, and it was even after
the publication of my treatise on intestinal worms that
this question, which seemed forgotten, was taken up
again by Pouchet. At present, they appear to have
given up parasites, which reproduce their kind like other
animals, and to have fallen back upon the infusoria, the
last intrenchment which remained to the partisans of
spontaneous generation, whence Mons. Pasteur has
scientifically dislodged them. It is evident to all those
who place facts above hypotheses and prejudices, that
spontaneous generation, as well as the transformation
of species, does not exist, at least, if we only consider the
present epoch. We are leaving the domain of science if
we take our arms from anterior epochs. We cannot
accept anything as a fact, which is not capable of proof.

CHAPTER VI.
PARASITES FREE DURING THEIR WHOLE LIFE.

Turs first category of parasites includes all those which
are not enclosed, and which live at the expense of others,
without losing the attributes and advantages of a wan-
dering life; they are as free as the vulture or the falcon
which pursues its prey. We shall not, however, include
among them the parasitical kite of Daudin, which tears
from the hands of the traveller a piece of the flesh
which he is preparing in the open air, nor the small
Egyptian plover, which keeps the teeth of the crocodile
clean. The former is a pirate, a highway robber; the
plover, on the contrary, is a kind neighbour, an attend-
ant who performs valuable services. .

We are more correct in considering as parasites the
Vampires (Phyllostoma), those audacious bats of South
America, which settle on the sleeping traveller or his
beasts, and suck their blood by means of the sharp pa-
pille of their tongue. These animals are winged leeches
which bleed their victim and pass on. We place among
free parasites the greater part of leeches, some in-
sects, and a certain number of arachnida, crustaceans,
and infusoria.

As we have mentioned free messmates, so we have

108 ANIMAL PARASITES AND MESSMATES.

\

free parasites, which take advantage of their host,
but with prudence and economy; they ask from him
nothing but his blood, and sometimes render him im-
portant services. Many of these animals, both mess-
mates and parasites, have at present been only pro-
visionally classified, and cannot be definitely arranged
till more observations have been made. It is not always
so easy as it may be thought to determine exactly the
relations which certain animals have with each. other.
We must pry very narrowly before we can ascertain the
motives which act on this inferior order of beings. It
is among free parasites that we find those organisms
which are generally called vermin, and which seem the
more capable of injuring their neighbours since they can
the more easily escape detection. These creatures,
though they are called vermin, excite no more repug-
nance in the mind of the naturalist than the other works
of creation; and St. Augustine did not exclude them from
his thoughts when he exclaimed, ‘‘ Magnus in magnis,
maximus in minimis.”

Leeches drink the blood of their victim, and when
they are gorged to the very lips, they fall off, taking a
siesta for weeks or months. Thus enjoying a repast
at very long intervals, it is useless for them to continue
longer at table; and this is therefore another reason that
they should usually preserve their organs of locomotion,
that they may use them after their long period of diges-
tion.

Like the annelids, they do not change their form, and
as they are only attached to their host for a short time,
naturalists have not thought fit to place them among
parasitical worms, or Helmintha. However, if we pass

PARASITES FREE DURING THEIR WHOLE LIFE. 109

from the higher kind of leeches to those which live at
the expense of fishes, of crustaceans, and especially of
molluses, we see that the desire of possessing a lodging
is developed by insensible degrees, and that the lower
kinds, are by their form, their organization, and their
mode of life, as dependant as the greater part of the
helmintha. Thus we see Hirudinide on the Mya, an
acephalous mollusc, incapable of quitting their place,
firmly fixed on the walls of the stomach of their host,
and living quietly at his expense. They are called Mala-
cobdellw, and they have been so ill-treated by Nature,
that it is necessary to submit them to minute investiga-
tion in order to determine their parentage.

The most well-known leeches are those which attack
man and the other mammalia, but some are also found
on other vertebrate animals, especially on fishes. Their
organization is always proportioned to that of the host
which they frequent; thus, the simpler their host, the
lower is their organization. The molluse harbours hiru-
dinide much lower in the scale than those which are
found in fishes, and especially in mammals.

Vampires make use of the papille of the tongue, and
also of their teeth, which act as so many lancets; leeches
apply their toothed lip, saw asunder the epidermis, and
with the mouth applied to a network of capillary vessels,
suck till they fall off, intoxicated with blood.

We give here the different appearances which the
skin assumes after the bite of a leech. (Fig. 4.)

Fig. 5 (1 and 2) represents the jaws; 1, the jaws in
their usual position ; 2, a single jaw, to show its outer
edge, which is cut with teeth like a saw.

Fig. 6 shows a leech with a section of its digestive

110 ANIMAL PARASITES AND MESSMATES.

tube. The letters d d indicate the different cavities of
the stomach, which are filled in succession. We see in.

Fig. 4.—Different forms of the bite of a Leech.

Fig. o.--1. Sucker, open; a. jaws. 2. One of the jaws magnified.

Fig.6.—Section of a Leech. a. anterior sucker; 0b. posterior sucker ; c. anus;
d. stomach ; @. esophagus; ¢. intestine; s. glands of the skin.

the fore part, the anterior sucker with the mouth, and
behind, the posterior sucker with the anus. At the

PARASITES FREE DURING THEIR WHOLE LIFE. 111

side of the stomach are seen traces of the glands of
the skin.

We find a great variety in the mode of life of these
hirudinide ; and if we sometimes meet with some which
are sober and delicate, the greater part show a voracity
of which it is difficult to form any idea. A leech has
been met with in Senegal which draws a quantity of
blood equal to-the weight of its body. There are leeches
which devour entire earth-worms. Fortunately the
greater species are not the most voracious: we might
feel rather uneasy in the midst of leeches similar‘to that
which Blainville has described under the name of Ponto-
bdella levis, which is not less than a foot and a half in
length. ;

It is generally thought that all leeches are aquatic,
but this is a mistake. In the warm regions of the Old
and New World, there live in the midst of the brush-
wood, leeches which attack the traveller as well as
his horse, and suck the blood of both without their
perceiving it.

Hoffmeister gives the following account with reference
to small leeches in the island of Ceylon :—

He had amused himself one evening by collecting
some phosphorescent insects which were hovering around
him in considerable numbers; on entering afterwards a
lighted room, he perceived streaks of blood all down his
legs. This was the effect of the bites of leeches. These
creatures, said he, made a painful impression on me, the
remembrance of which was terrible. This same leech,
which bears the name of Hirudo tagalla, or Ceylonica,
lives in the thickets and woods of the Philippine Islands.
There also it attacks horses as well as men. It has

112 ANIMAL PARASITES AND MESSMATES.

also been noticed on the chain of the Himalayas, 11,000
feet above the level of the sea. Japan and Chili also
have terrestrial leeches. The Cylicobdella lumbricoides
is a blind leech, which has been found by F. Miller in
damp earth, in Brazil.

The aquatic leeches are better known, and with but
few exceptions, the accidents produced by them are little
to be feared. In Algeria it is not uncommon, as army
surgeons tell us, to see soldiers, while drinking spring
water, swallow small leeches which may do them injury.

We find from official reports that the French soldiers
often suffered, during the campaigns in Egypt and
Algeria, from an aquatic leech (Hamopis vorax), which
attacked the mouth and the nostrils, and did not respect
man any more than horses, camels, and oxen. The
leech discovered by Dr. Guyon under the eyelids and in
the nasal fosse of the crab-eating heron of Martinique, is
probably a monostomum, and not one of the hirudinide.
Leeches have also been found on turtles under the name
of Eubranchella Branchiata. Say saw one on a chelonian,
and others on tritons and frogs.

It is especially upon fish that these worms are found,
and we cannot hesitate to consider the greater part of
them as true parasites. We have described a whole
series of them which live upon marine fishes, especially
on the barbel, the bass or sea-wolf, the halibut, the dab,
and different species of gadide. A. E. Verril published
last year the description of several kinds of American
leeches, among which we see two which infest a fish
(Fundulus pisculentus) of West River, near Newhaven.
A large and beautiful species, which is known by the
name of Pontobdella, is also found upon the Rays.

PARASITES FREE DURING THEIR WHOLE LIFE. 118

A very skilful naturalist, Mons. Vaillant, has lately
made these animals the subject of study. Mr. Baird, in
1869, made known four new Pontobdelle, one from the
coast of Africa, two from the straits of Magellan, and
one from Australia, found in one of the Rhinobatide.
But the most interesting in every point of view are the
Branchellions, which inhabit the electrical fishes known
under the name of torpedoes, and which do not fear to
choose an electric battery asa place of abode. These
branchellions always attach themselves, as it appears,
to the lower surface of the body, and not to the gills as
has been thought; and they are distinguished from all
their congeners by tufts of filaments along their sides,
which have been compared to lymphatic branchie.

Many naturalists have considered these curious worms
worthy of attention, and have made many interesting
observations upon them. One of the finest memoirs
cn this subject is that of Mons. A. de Quatrefages. We
may here mention, in connection with their mode of life,
that neither Leydig nor Quatrefages found globules of
blood in their digestive cavity. The branchellions live
on the mucous products of the secretions of the skin, and
instead of being parasites, we may consider them as
worms paying liberally for the room which they occupy in
their host, by maintaining his skin in good condition.
They ought rather to be classed among animals which
render service to others; that is, among mutualists.

In the fresh waters of Europe, a little leech-like
animal, beautiful both in form and colour, fixes itself
on carps, tenches, and other Cyprinide; this is. the
Piscicola geometra, which also lives on the Silurus glanis.
They are sometimes found in such great numbers that

114 ANIMAL PARASITES AND MESSMATES.

they form around the gills a kind of living moss, which
at last kills the fish.

There are different leeches atch inhabit invertebrate
animals. Rang mentions a little creature of this kind
in Senegal, living as a parasite upon the respiratory
apparatus of an anodont. Gay discovered in Chili one
of the Hirudinide in the pulmonary sac of an Auricula,
and another on the branchie of a crab (Branchiobdella
Chilensis). Mons. Blanchard has noticed a malaco-
bdella in the branchie of the Venus exoleta; and it was
known in the last century that the Mya truncata of our
coast also lodges a malacobdella which lies always under
the foot of the animal. This is the hirudinean of which
we have spoken above, which is allied transitionally to
the trematoda. .

Together with the Hirudinide, we find very small
worms, transparent, bristling with daggers and spikes of
every form, which are found everywhere in fresh water.
They are known by the name of Nais. They are so
completely transparent that we can see the action of all
their organs through the substance of the skin. They
have been the subject of several remarkable works.

They live freely among the leaves of Lemna and
other aquatic plants; but there is one species much
more restricted in their habitat than the others; these
seek assistance from the Lemnee, and live at their ex-
pense. It is because of this kind, of which the genus
Cheetogaster has been formed, that we mention them
here. Their long bristles are veritable halberds, which
they employ with astonishing skill, both in attack and
defence.

Among free parasites are found many very important

PARASITES FREE DURING THEIR WHOLE LIFE. 115

articulated animals, which neither the naturalist nor the
physician ought to ignore. Some of these increase with
frightful rapidity on the skin which harbours them, and
their name alone is sufficient to inspire disgust, if not
horror: others live like leeches at the expense of dif-
ferent animals, but without inhabiting them. There are
many of these which follow their host everywhere, and
which are dreaded not without just reason.

Of this kind are gnats, fleas, lice, bugs, and a great
many others, among which we ought not to forget the
acaride, nor those singular parasites of bats, which
bear no slight resemblance to spiders swimming in the
midst of the fur. Volumes might be written concerning
the organization and the habits of these parasites. These
small creatures inspire the naturalist with no more
disgust than the earth-worm of our flower-beds, or the
salamanders of marshy places. Each one plays its part
according to its conformation, and the most abject in
appearance is not always the least useful.

We will select among these parasites some two-winged
insects, among which there are many which suck blood.
Those which are generally called flies are divided into
two groups, under the name of
Nemocera and Brachycera; many
of these live only on blood, and
are more terrible than the lion
and the tiger; in many coun-
tries man can defend himself
against those fierce carnivora, Fig. 7.—Antenna of a Gnat.
but he is there. completely

~ powerless and without defence against these insects.
Among the Nemocera are found the gnats (Culex

116 ANIMAL PARASITES AND MESSMATES.

pipiens), those brilliant children of the air, with fine
and slender claws, and delicate membranaceous wings,
and wearing on their heads feathery antenne of rare
elegance. They are known in the Old as well as in the
New World, and in southern regions it is necessary to
guard against their nightly attacks by musquito curtains.
In the Antilles they bear the name of Maringouins, and
in hot countries they are generally known as musquitoes.
They are also called gnats, midges, black-flies, zanzare,
&c., in different localities, but as may be supposed, these
names do not always designate the same insect. The
musquitoes of the French colonies are often Simulia.
At Madagascar and the Isle of France is found the gnat
known by the name of Bigaye.

In Davis’s Straits, in lat. 72° N., Dr. Bessels, on
board the Polaris, was obliged to interrupt his observa-
tions on account of these insects. A great number of
them have been seen up to the 81st degree of latitude.
Besides gnats, there were also found Chironomi, Corethre,
and Trichocere.. As Dr. Bessels was able to save from
the Polaris some small collections of insects, we shall
soon know the names of the species which live in these
high latitudes. It is said that the Hsquimaux and
the Lapps cover their skin with a coating of grease, not
only to lessen the effect of the cold, but to defend them-
selves from the stings of gnats.

“The gnat is a plague from June till the first frosts,”
says Mons. Thoulet, speaking of his abode among the
Chippeways. ‘‘It renders the country almost uninhabit-
able; and one is so exhausted by this suffering, which
does not cease by night or by day, and by the loss of
blood through their bites, that we manage to get through

PARASITES FREE DURING THEIR WHOLE LIFE. 117

our daily task only by the force of habit; we can neither
speak nor think. When the musquitoes disappear, the
‘black-flies’ come: the musquito pumps up a drop of
blood and flies away; the black-fly bites and makes a
wound which continues to bleed.”

De Saussure has alluded to curious relations which
exist in Mexico between a bird, a beast, and an insect.
‘Bulls bury themselves in the mud,” says this learned
traveller, ‘in order to avoid the attacks of gnats, leaving
in the air only the tip of their nostrils, on which a
beautiful bird, the Commander, posts himself, in this
position the Commander watches for the Maringouin
which is bold enough to enter the nostrils of the
animal.”

Gnats are parasites in the same manner as leeches,
since, like them, they suck the blood, and live at the
expense of others. There is, however, this difference,
that the females only are greedy of blood; if this fail
them, they live, like the males, on the juices of flowers.
Another difference is that they are completely harmless
till they have wings, and though they live long under
their first form, in damp earth or in water, the duration
of their life as perfect insects is of short duration.

We need not trouble ourselves about the active larve
which swarm in stagnant water, nor the chrysalids
which float immovable in their natural sepulchre. We
give on the next page a representation of a larva of the
gnat. The females alone pierce the skin by means of an
auger with teeth at the end; they suck the blood, and
before they fly away, distil a liquid venom into the
wound. This bite seems to have an anesthetic effect,
which does not cause it to be felt till some time after.

118 ANIMAL PARASITES AND MESSMATES.

The little spot around the wound appears as if affected
by chloroform.

Fig. 8.—Gnat (oulex 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
Culicids, 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 Rhagio, 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

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.—Lueilia 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 fosse.

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, Tabanus 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,

Vig. 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.—Flesh 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 in

PARASITES FREE DURING THEIR WHOLE LIFE. 123

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 Pieroptus 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 Idng claws like a spider, and plunges deeply into
the fur. These Nycteribie 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.”

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
singular 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 victim 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 pgrasites, and belong to a different
order of insects. Their mouth ig 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 nits. 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 like 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 racés of men.

The name of helminthiasis has been proposed for
worm disease in general, and either teniaceous 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
Tiead.

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, are commonly met with on the sandy
shores of the Mediterranean, 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. Ido 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
germs.

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 theix 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 FREL DURING THEIR WHOLE LIFE. 131

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
is not 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 cause of
the itch, that he offered a
prize to any one who could
render these insects visible.

Fig. 21.—Sarcoptes scabiei, or male
acarus of the itch; the lower
surface.

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 itch-insect, and this error
had caused it to be supposed that the species peculiar to

Fig. 23.—Sarcoptes 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 Lecgons sur les maladies de la peau (Paris 1863),

devotes a special chapter to parasitical diseases, and gives the complete
history of the itch-mite.

PARASITES FREE DURING THEIR WHOLE LIFE. 133

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. Fiestenberg
has lately published a folio volume, under the title of
“ Die Kritzmilben der Menschen und Thiére,” 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 Linguatulz, the
structure of which has been so long doubtful. The
Simonea folliculorum belongs to the family of the Demo-
dicide.

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 acaride, 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 Bairdti, and an
Argas Americana on cattle coming from Texas; this
was published in the sixth report of the United States’
Geological survey (1878).

According to the observations of Mons. Megnin, the
Tyroglyphi, the Hypopt, the Homopi, and the Trichodactyli,
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 ovi-
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

186 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 Campanularia
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 Hydrachne
(Fig. 24) which frequent aquatic animals. The Leptus
autumnalis, known in France, at least in some locali-
ties, by the name of Rouget, is 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 Méricourt
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.

188 ANIMAL PARASITES AND MESSMATES.

CHAPTER VII.
PARASITES FREE WHILE YOUNG.

We have brought together in the former chapter the
animals which live 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; like 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 off-
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 Bonellie
which live freely in the sand, and whose males establish
themselves parasitically on the sexual organs of 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
grown. 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 Lerneans, 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 Pe
spoken in the preceding Fig. 28. —-Female Chigoe.
chapter; while the female finds for herself a hiding-

142 ANIMAL PARASITES AND MESSMATES.

place, and becomes of such a monstrous size that the
entire insect is 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 a mammal. It is called Ieodes 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 a lady 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 had a 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. 1438

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, &c. 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. R. 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 Miller 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, Iones, Phryxi, Gyges, Athelgi, &e.

2. Those which live in the thoracic cavity of some
Brachyuri, as the Entoniscus. *

3. Those which live in the cirrhipeds, like 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 Iones 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, Me. 2—Phryxus tall
Another parasite of this group has naturai size is given
been observed by Fr. Miiller at Des- ** te si4*
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 Lerneoniscus, 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 Zeugo. Another
isopod, with a no less decided recurrent development,
has received from the same naturalist the name of
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
Jellinghausti. This isopod crustacean, living at first in
‘the same manner as the rest, looks out for a small
cyprinoid 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,

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
recusrent 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 themselves 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 eares 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.

It 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 Nawplius 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 Cypring. 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 branchize —¥'S,31-Uernes bran-
of the Maia squinado, the sea-spider of _—thegills 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 Aplidium 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 mamillaris,
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 Sarsii. The genera
Selius, Silenium, Terebellicola, Chonephilus, Sabellacheres,
Nereicola, &c. infest all the annelids; the Eurysilenium
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 Lilljeborgii 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 Girardiz, according to
Mons. Lacaze Duthiers, feeds on an. Antipathes. A
Leemippus (Proteus) lodges in the cavity of the body of
the Lobularia digitata of Delle Chiaie; and lastly, the
Enalcyonium rubicundum is sheltered by the Alcyoniwn
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. 82), 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
eges. The Filaria at
last is so entirely atro-
phied that Professor
Jacobson, after having
seen it alive on one of aioe d. Anus; 3, Section of the

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

a is

( ecu
oo cannaunsil?

Wigs 32.—Young Filaria of Medina; 1,
nterior extremity ; c. Mouth; 2, Caudal

154 ANIMAL PARASITES AND MESSMATES.

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 créche, 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 had remained for a certain time in horse-dung in
order to hasten the decomposition of the soft parts. They
had 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, I 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. 157

eggs; 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 sricll 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,
the 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 nigro-venosa alter-
nately produces individuals of separate sexes, that is to
say, if the monecii produce diccii, and the dicecii again
moncecii, 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.
Meeznikow, 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 Entoconcha. 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. Miller 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 not
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 Trichodinez. 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 havea

lage)
rae

Fig. 33.—Gregarina of Nemertes Fig. 34.—Sac with Psorosperinias
Gesseriensis. 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-
spermiz. Fig. 84 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 Ehrenbergit; Schneider
represents the various phases of its de- (R3)Wqumns
velopment. In the autumn of 1871, nearly “"*°f ‘he Asrion.
all the mesostomes perished through the presence of
these parasitical organisms: in the following year they
were rare.

Some years ago, Kolliker discovered on the spongy
bodies of molluscs, 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.

162 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
seck 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 itseli
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 isthe most dreaded
on account of its great fecundity, is precisely that which
is 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 respeet to plants will be counterbalanced by the
number of ichneumons which arrest the propagation of

166 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 Evaniade, the Chalcidid#, as well as the
Tachinariz, which are remarkable for this kind of life.
At the moment when the mining hymenoptera introduce
into their hiding-places the insects which they have
seized, and which they destine for their young ones,
the Tachinarie 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 (Euphorbia helioscopa) grows abun-
dantly,.and the natural guest of this plant is a Sphynx.
While this sphynx is still a caterpillar, a dipterous
tachinaria 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
in 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 after
another. The seeds of this plague were also sown in
France, in the environs of Paris. Mons. Eug. 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 come 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 devolved 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
egg 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 proprietor serve
as rations for the usurper.

In this manner, the Ophionewri live, in their 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 even
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, nof 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 cells, 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 larvee of the Sphex. The
mother of these hymenoptera takes care to deposit her
eges, 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. 171

insects, show their cruelty in a different manner; they
live in the bodies of the larve of Cecidomye 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
Meloé 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.

edex, 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 hwmeralis has a progressive develop-
ment at first, a recurrent one afterwards, and then again
it becomes progressive.

Aphides which are not yet 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 victrix) 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 Gistri. We give the representation of the species
which attacks the horse.

36.—CEstrus of the Horse

Hinder 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. 175

little. 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
cestri 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.

174 ANIMAL PARASITES AND MESSMATES.

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 theur 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 gadfly 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 FRE 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 Ciistride 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 Echino-
mye 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. 177

; The Melophagus of the sheep is a wingless dipterous
insect, like the Lipoptena of the stag. We give figures
of these two curious insects.

Fig. 38.—Mclephagus 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 to 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 eréche, 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 MESSMATES.

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 hving cradle to
scatter its eggs abroad.
In this case, the embryos
themselves go to seek for

‘ — | : their host, and unlike the
Fig. 40.—Gordius aquaticus, natural size. .
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

PARASITES THAT ARE FREE WHEN OLD. 179

in leneth, 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 morith; 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 tlird,
like the first, in a sexual state.

To judge by some specimens of gordius brought from
India, these curious parasites exist not-in Europe 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 psorospermia.

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
ean 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 (Anguillulina dipsaci). Tt 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
Rachitis.

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 ceERTAIN 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
créche with its nurslings passes into the lying-in
asylum. The créche 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 Teniz.

‘We might call the rabbit or the mouse which har-
bours worms in 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 intermediate 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 gastric 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 créche 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 transmigrations 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 without 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 whieh 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 Tristomid# and all the worms of that
group, which also stand higher in their organization : we
shall speak of them hereafter. The other trematodes,
which are called digenetic, live on the most dissimilar
animals, under the most varied forms, and, like the
greater 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 cosmopolitan; as inconstant in
their progress as capricious in the choice of their com-
panions. Hach distome resembles a small leech which
_ hag 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 experiments 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 Leipzic,
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 microscopi¢ 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 mollusc, it disembarks, 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 molluses,
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 cercariz
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 ciliated embryos,
wandering without guidance and

Fig. 41.—Monostomum verru-
cosum, Sporocyst with Cer-
eariz. In front is the mouth,
in the middle the digestive
canal, and around the diges-
tive canal are young ones,
under the form of Cercarie
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 Cercarie, which was given to
them ata 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 cilie, 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 cercarie 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. Miller 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 MBHTAMORPHOSES. 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, cercarie 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 Sarsie and Oceania,
but always sexless.

The Cercaria setifera of J. Miller 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 mollusc 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 molting, 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 cercaria has only to examine some
fresh-water molluscs, either the Limnew 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
resides in the liver of the sheep.
Bi ye nee ot tvloeite In order to discover it, we have

¢, digestive tube; d, abdominal only to 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 Limaw 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 porte 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 Distomuwm 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 oily 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 Distomum 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 mollusc, 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 raii.
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 really like diccious worms. We find, however, a
more remarkable instance in the Monostomum 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
cyst, 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. It lives in the sub-orbitary sinus
of several aquatic birds; that is to say, in the nasal
fosse, 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

iz noe
Fig. 43.—Monostomum Fig. 44.—Monostomum mutabile. Ciliated embryo with
mutabile (adult). sporocyst and young cercarix, 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 cilia, 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 cerearia, 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 mollusc 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 millimétres in length
(about *13 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.—Cerearia 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 cercaria 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 group, 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-
métres in length (about ‘23 of an inch).

We close the history of trematode worms by giving
the figure of a beautiful one known under tlie 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.

Fig. 47.—Amphistomum sub- Fig. 48.—Polystomum
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 teniz 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

es ribbon; it 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
(@ xenosite); but indepen-
dently of this stranger, it
Fig. 49.—Cysticercus; a, upper part of gives hospitality toa special

the resto; ©, place where the vesicle toni in its intestines. This
worm; d, the head, showing the : .

suckers and the crown of hooks. is its own worm, the Txnia
pectinata, which is a nos-

tosite. All the herbivora are in a similar case; the ox
and the sheep possess a peceliar 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 endure 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 which, 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.

“It 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, while 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,

Ps

TRANSMIGRATIONS AND METAMORPHOSES. 211

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, is
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

212 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 teenia 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 saws 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 parasites, and
these in their turn are not always 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 Tznia 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 cestode 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 (Tznia
solium), it will enable us to understand all the others.
Known by the name of tenia, or solitary worm, it is, like
all the cestodes, a marvellous association of mothers

914 ANIMAL PARASITES AND MESSMATES.

and daughters, which are developed and vegetate in
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

ed

=
Fe

|
|
i
E

ze

Fig. 51.—Tenia solium, or solitary worm ;

a, head, or scolex; 5, tape formed of Fig. 52.—a, Rostellum ; 6,
many individuals, the last of which, com- crown of hooks ; ¢ ¢, suck-
pletely sexual, separate under the name ers; 1, scolex of the tenia
of proglottides, and represent the adult solium; 2, hooks expanded;
Pe complete animal, Each solitary a, heel of the hook.

worm is a colony.

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 Linnzus.

The measles in pork have been attributed to damp,
to feeding on acorns, to heréditary 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. Kichenmeister 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
tenie, 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 Tznia solium.

We have ourselves caused a pig to swallow eggs of
the tenia, and have given it the measles. Messrs.
Kiuchenmeister and Haubner, who were ordered by the
government of Saxony to make some experiments, also
caused three pigs to swallow eggs of the Tenia solium,
and two of these were affected with measles. A piece of
flesh, weighing 43 drams, contained 188 cysticerci, which
amounts, for 22 German lbs., to 88,000 cysticerci.

-The use of raw pork will produce teni# more readily
than raw beef. Dr. Mesbach has given the following
instance in support of this fact. At Dresden, a father

TRANSMIGRATIONS AND METAMORPHOSES. 217

and his children regularly ate, at their second breakfast,
raw beef, but one day they took pork instead, and eight
weeks afterwards one of the children, when in the bath,
voided two ells of Tznia solium.

The etiology and prophylaxis of the solitary worm,
that is to say, its mode of introduction, and the means of
protecting ourselves from it, are clearly indicated. It is
sufficient to introduce one of these vesicles into the
stomach in order to have the tape-worm. The experi-
ment has been made: young men have ventured, in the
interests of science, to swallow some, and have ascertained
how many days were required for the parasite to be
sufficiently complete to give off segments with the feces.

These vesicles in pork come from the eggs which the
tenia has scattered in its passage, and if the pig comes
by chance in contact with the fecal matter of a person
infested by one of these worms, it is soon infested and
becomes what is’ called measled; in this fecal matter
there are either free eggs which have been evacuated by
the worm, or else fragments, known long since under the
name of.cucumering, which are full of eggs.

These fragments of tenia, which I have proposed to
name proglottides, and which are nothing else than the
worm in all its sexual maturity, are still living and
wriggling at the moment of their evacuation, or else they
are dead and often completely dried ; but in either case,
they are full of eggs. Each egg is surrounded by mem-
branes and shells, which effectually protect it against all
dangerous contact.

A fragment of the mature tenia, thus filled with eggs,
when introduced into the stomach of the pig, is rapidly
digested, and the eggs are set at liberty. These lose

218 ANIMAL PARASITES AND MESSMATES.

their shells by the action of the gastric juice, and there
issues an embryo singularly armed. As we have before
said, it carries in front two stylets in the axis of the
body, and on the right and left sides two other stylets
curved at the end, which act like fins. These embryos
bore into the tissues as the mole burrows into the soil.
The middle stylets are pushed forward like the snout of
the insectivore, and the two lateral stylets act like the
limbs, taking hold of the tissues and forcing the head
forwards. In this manner the embryos perforate the walls
of the digestive tube.

An egg of the Tenia solium may be swallowed by a
man instead of passing into the stomach of the pig. It
is hatched in his stomach precisely in the same manner,
and the embryo takes up its lodging in some enclosed
cavity. Some have been found in the eye-ball, in the
lobes of the brain, in the heart, or in the muscles. We
have lately read an account of the effects produced by
one of these wandering worms, on a man who died after
suffering from a peculiar disturbance of the mind. Two
spirits seemed to haunt and speak to him, the one a
German, the other a Pole. Filthy images were called
up before his imagination. At the post-mortem examina-
tion, cysticerci were found to occupy the sella turcica,
near the commissure of the optic nerves. One of these
‘was alive, the others were calcified. Two others in a
similar condition occupied a lobe of the brain.

Man harbours not only the Tania solium, but
another spécies very similar, which naturalists have only
learned to distinguish from it during the last few years,
the Tenia medio-canellata. We give a magnified repre-
sentation of the scolex, that is to say, of the head of this

TRANSMIGRATIONS AND METAMORPHOSES. 219

worm, which has no crown of hooks in the middle of its
four suckers.

This solitary worm is introduced
by means of beef, and the cysticercus,
during its abode in the cow, mani-
fests already the peculiar character-
istics which enable us to recognize
the species, that is to say, no crown
of hooks, but four suckers, and in
the middle of them, some blotches
of pigment. Leuckart fed a calf with
eggs of this tenia, and at the end of
seventeen days, the animal died of sp 53, -Teniamedio-
acute miliary tuberculosis, produced ee
by the great abundance of cysticerci. This second
species, which had been always confounded with the
preceding, and which is nevertheless the more common,
has therefore a different origin from the Tznia solium.
Observations made quite recently in the north of Africa
demonstrate this. Great difficulty had sometimes been
felt in explaining the presence of the tenia in persons
who had not eaten pork. This embarrassment arose
from the confusion of the two species, and this con-
fusion is the more easy as the head of the colony must
necessarily be found in order to distinguish them.

Scharlau, at Stettin, found tenie in seven children
who had been fed, on account of anemia, with raw meat.
The teniz were those ofthis species. We have ourselves
found them in children to whom the use of raw meat
had been prescribed.

We do not think it necessary to speak here of a
third species of tenia (7. nana), which also lives at our

220 ANIMAL PARASITES AND MESSMATES.

expense, but which has been hitherto found only in
Egypt.

We know perfectly well the itinerary of the Tenia
serrata of the dog, which is so abundant, that there are
few of these animals that do not enclose some and even
nmoaany of them. There are few except lapdogs which do
not harbour them. We can easily assign the reason.
Hivery tenia, like every animal, has its eggs; each
plant has its seeds. These eggs are laid by the mother
in the most favourable condition for the development of
her progeny. The dog deposits its dung on the grass
rather than in any other spot, because the eggs of its
tenia, which are destined to the rabbits or hares, will
have greater chance of arriving at their destination
than if they were exposed on the bare earth, or in the
water. Their prodigious number is calculated accord-
ing to the chances of their arriving safely. The egg,
when introduced into the stomach of the rabbit, is
rapidly hatched in this organ under the action of the’
gastric juice, and the embryo which is produced from
it seeks its hiding-place in the midst of the tissues
which surround it; it bores into them, and establishes
itself in the folds of the peritoneum. Then, once in its
resting-place, it barricades itself, and waits patiently
for an opportunity of introducing itself into the stomach
of the dog.

This microscopic embryo is armed with six hooks, like
embryos of all the cestodes; it employs them with much
dexterity to pierce the walls of the organs, and to lollow
out a space for itself in the substance of the tissues. Shut
' up in its hiding-place, membranes form around for its
protection; its six hooks, having become useless, wither;

TRANSMIGRATIONS AND METAMORPHOSES. 221

other hooks in the form of a crown Appear by the side
of four rounded projections, the future suckers; and,
sheathed in a large vesicle full of a limpid fluid, it waits
patiently for the moment when it will find a place in the
stomach of a dog. If good fortune awaits it, it will wake
up, some fine day, in the stomach of the animal which
has eaten the rabbit, its former home, and a new life
will commence for it. The organs in which it was im-
prisoned are digested, it gets rid of all its swaddling-
clothes, unrolls itself, separates from the vesicle which
has protected it hitherto, and penetrates into the intes-
tine ; there, immersed in the food of its host, it grows
with extreme rapidity, and assumes the form of a ribbon
or tape. The ends of this tape are successively matured,
detach themselves, and become the complete worms, full
of eggs, which are evacuated with the feces; scarcely
have they made their appearance in the open air before
they burst and scatter their eggs.

He whose scientific curiosity is sharpened, has only
to watch the dung of the dog at the moment of its
evacuation to distinguish on its surface worms of a
milky-white colour, contracting like leeches, which are
the true Tenia serrata in its adult state. Experiments
made on this species have given sanction to what I had
said respecting the cestodes.

The tenia, under the name of Cysticercus cellulosus,
lives in the folds of the peritoneum of the rabbit and
the hare, and passes directly from uae rabbit to the dog
to become complete.

It is very curious that the fox, so nearly allied to the
dog in appearance, and which also eats rabbits, never has
the Tenia serrata, but this animal nourishes other worms.

TES. —
ANIMAL PARASITES AND MESSMA'

: scerci that I made experiments
ae reas me to Paris, in order to
on pune who could not believe in the migration
— sites. Ib was this species that I gave also to the
dogs which served as a demonstration at Paris at the
course of lectures given by Mons. Lacaze Duthiers.
Some years ago, while making a post-mortem ex-
amination, at the Museum of Paris, of some young dogs
which I had previously infected’ with Tenia serrata at
Louvain, there were found by the side of these some Teniz
cucumerine. These dogs had taken nothing but milk
and cysticerci! Whence came these Tenie cucumerine?
I knew not, and I frankly owned it to the members of
the Commission who proposed the question to me. This
however did not prevent my being greatly puzzled with
the presence of this worm of whose origin I had no idea.
Now we know whence they came. An acaris, the Tri-
chodectes, lives in the hair of young dogs and harbours
the scolex of this cestode. The dog, by licking its own
hair, grows infested, like the horse, which in a similar
manner introduces the gad-fly, and although it has taken
no other nourishment, harbours its own epizoaria.
The name of Cysticercus tenuicollis has been given to
a vesicular worm which inhabits the peritoneum of the
ox, the goat, the sheep, &c., and which turns to a tenia
in the digestive tube of the dog. Mons. Baillet has made
the ‘principal experiments on this transmigration. The
itinerary of another cestode worm, the Cenurus of the
re : eee iH aig pnronge the sheep in order to reach the
wolf or the dog. i f :
nized in its ieaeid paced ae pi ely Beat 26008

on
long known under the name of (ie eae
eorats ; this

22.2

TRANSMIGRATIONS AND METAMORPHOSES. 223

develops itself on the brain of the sheep, and occasions
the disease known by the name of ‘“‘gid.” This disease
may be produced artificially. The sheep which swallows
the eggs of this tenia shows the first symptoms of it
towards the seventeenth day. If we kill it at this time,
we find on the surface of the brain, either at the base or
the summit, or sometimes between the hemispheres and
the cerebellum, one or more white vesicles of the size of
a pea, and on which no traces of buds are yet to be seen.
This vesicle, of a milky-white colour, and filled with
liquid, is the scolex. Near these vesicles are to be seen
some very irregular yellow furrows, like tubes abandoned
by some tubicolar annelid; this is the gallery through
which the vesicular worm has proceeded to the place
where it has been found.

A fortnight later, that is
to say, about the thirty-
second day, the ccenurus is
as large as a small nut, and
one can see with the naked
eye some small nebulous cor-
puscles, separate from each
other, of the same form and
size; these are the buds or
scolices which have risen
up, but which, as yet, have
neither hooks nor suckers.

We give the representa- Fig. 54.—Ccnurusof the sheep. 1, the
tion of one of these vesicles, with the selioed tathen nace werthta
on the internal walls of which”
young scolices have been developed; this is nearly of the
natural size. Fig. 2, a, a, shows these scolices of nearly

22.4 ANIMAL PARASITES AND MESSMATES.

the natural size. Fig. 1 represents an isolated and
magnified scolex; A, shows the segments of the future
proglottides; D, the suckers; C, the hooks; H, the
vesicle which contains them.

Eggs of the same tenia have been given to sheep at
Copenhagen and at Giessen, and Messrs. Eschricht and
R. Leuckart have obtained the same result as we had at
Louvain. On the fifteenth or sixteenth day the first
symptoms of “gid” declared themselves. At about the
thirty-eighth day the crown of hooks appeared, the
suckers were. formed, and the whole head of the scolex
was sketched out. All these heads can leave or enter the
sheath at the will of the animal. It is truly a poly-
cephalous animal when the scolices are expanded. This
worm continues to grow for a long time in the cranial
cavity, and produces by its presence the gravest results.
The sheep necessarily dies at last, unless we remove
the parasite by means of the trepan.

The cenurus, at this point of development, swallowed
by a dog, undergoes great changes in a few hours. The
proscolex, or large vesicle, withers; the different scolices
unsheath their cephalic extremity, become free, penetrate
into the intestine with the food, and attach themselves to
its walls, so as to form as many colonies of tenia as there
are distinct heads. A dog which has swallowed a single
cenurus may therefore contain a considerable number of
teenie.

The development of this worm proceeds very rapidly,
and it only requires three or four weeks to attain many
feet in length. The organization of this worm, in the
state of strobila and of proglottis, is in every respect like
that of the Tznia serrata; we have even endeavoured in

TRANSMIGRATIONS AND METAMORPHOSES. 225

vain to distinguish these worms from each other by their
hooks. The wolf or the dog follows the flock of sheep,
scatters the proglottides or the eggs in their way, and the
sheep, browsing on the grass with the eggs attached,
become infested with their most dangerous enemy.

To arrest this disease, only one thing is necessary, to
destroy by fire the head of every sheep attacked by the
“gid.” The rest of the animal may be eaten without
danger.

Pouchet did not succeed in giving sheep the ‘‘gid” at
first, for the very simple reason that he employed the
eggs of the Tenia serrata, instead of those of the Tenia
cenwrus; he had confounded the two species. The
conurus of the sheep is a true calamity when it spreads
in a country. The animal attacked by it is lost, and the
mischief may be indefinitely propagated by giving as food
to dogs the head of the sick animal, with thousands of
young tenia enclosed within each.

There exists a singular cestode which bears the name
of Echinococcus. We give a figure of the echinococcus
of the pig, slightly magnified, and an isolated scolex
(Figs. 55 and 56). In its first form it is composed of
closed sacs, which grow to the size of a nut, and some-
times to that of an orange. It usually lodges in the liver
of the pig, but establishes itself also in man. We have
been assured that part of the population of Iceland have
been attacked by it. The abundance of this parasite in
that country is attributed to the want of cleanliness, and
the number of dogs that they keep around them. The
echinococcus becomes a tenia in this animal. It scatters
the eggs with its dung, leaving them directly or indirectly
on plants which the Icelanders eat ; for they gather for

226 ANIMAL PARASITES AND MESSMATES.

food certain mosses, sorrel, cochlearia, dandelion, &c.,
from the midst of the plains in which live flocks of sheep
guarded by dogs. The eggs are scattered everywhere on
plants or in the water.

Leuckart has made some very interesting experiments
on the echinococci. In Fig. 57 is shown a tenia which
proceeds from an echinococcus.

Fig. 55.—Isolated scolex of the Tenia echinococcus
’ from the pig.

eS

Fig.-56.— Tenia echinococcus, from the pig. Fig. 57.--Tenia echino-
coccus, from the dog.

There is yet another tape-worm harboured by man,
the Tzxnia lata, better known under the name of Bothrio-

TRANSMIGRATIONS AND METAMORPHOSES. 227

cephalus. We give in Figs. 58, 59, and 60 representations
of this worm in the state of a colony, also the scolex or

ia?

at

gacadd

aati

i
i
|. J
8
H

daaadauaeaaaa

Fig.59.--Bothriocephalus latus, scolex,

PEt

ECOCerer

PeagIs

adaaz

noe,
el Bi

Fig. 58.—Bothriocephalus latus. a@,scolex, Fig. 60.—Bothriocephalus latus,
6, the proglottides, c, the sexual organs. egg.

head separately, and an egg. Its history is very curious,
especially with reference to its geographical distribution.

228 ANIMAL PARASITES AND MESSMATES.

It is only found in Russia, Poland, and Switzerland, and
the limits of the places which it inhabits are perfectly
defined. Siebold, during his stay at Konigsberg, could
determine from the nature of the worms, whether the
patient who consulted him lived on one side or the other
of the Vistula.

A Russian naturalist, Dr. Koch, thoroughly studied
this interesting worm and its evolution. He says that
this cestode is rare at Moscow, while at St. Petersburg,
Riga, or Dorpat it is common. If this be really the case,
it must doubtless be attributed to the fact that in one
place the inhabitants drink spring water, and in the
other water from the river.

A very curious circumstance is the actual rarity of
the Bothriocephalus among the inhabitants of the shores
of the Lake of Geneva, though formerly it was very
common there. This diminution, if we may not call it
disappearance, is due to the change which has been
made in the construction of water-closets, all of which
formerly emptied themselves into the lake, so that the
embryos were hatched in the water, and persons were
infested by them through drinking it. At present the
refuse of the towns is carefully collected for the purpose
of manuring the land. This is the result of the advice
of Mons. de Candolle, half a century ago; for this
naturalist clearly understood how great was the loss to
agriculture from the neglect of this fertilizing agent.

The itinerary of this tape-worm is simple. It passes
from man to the water under the form of an egg, or of
a proglottis ; and from the water to man in the shape of
a ciliated embryo. In this manner it is introduced with
the water that is drunk. The Bothriocephalus, like

TRANSMIGRATIONS AND METAMORPHOSES. 229

other cestodes, is free at the commencement and the end
of its life: at the beginning, in order to penetrate into
its host; at the end, to scatter its eggs.

Messrs. Sommer and Landois published, in 1872, an
anatomical description of the sexual organs of the
Bothriocephalus latus, of such completeness, that it
will be long before any one will again take up this sub-
ject, which had so much occupied helminthologists ever
since the celebrated work of Eschricht. This memoir is
illustrated by superb engravings, which represent these
organs under every aspect. Dr. Béttcher, of Dorpat,
found in the small intestine of a woman, who died of
peritonitis, at least a hundred Bothriocephali. They
were but slightly developed, though there were some in a
sexual state.

The largest tenia, though not the longest, is the
Tenia magna, from the Rhinoceros, described by Marie;
it is, no doubt, the same to which the name of gigantea
was given by Peters. The learned director of the
Museum of Berlin gave me a fine specimen of it eighteen
years ago. The generic name of Plagiotenia has been
proposed for this worm.

Almost all birds nourish large and beautiful tania,

but they must be studied immediately after the death
of their host. They often change their form entirely
at the end of a few hours.
Woodeocks and snipes always have their intestines
stuffed full of teenie and the eggs of these worms. Livery
bird contains them by thousands. Fortunately we can-
not be infested with the tenia of the snipe and the
woodcock.

Fig. 61 represents the scolex of the Tenia variabilis

230 ANIMAL PARASITES AND MESSMATES.

of the snipe, and Fig. 62, by its side, shows the crown
of hooks more highly magnified. We have made these
drawings from worms collected from snipes some instants
after their death. We close this chapter on the cestodes

Vig 61. Tenia variabilis Fig. 62.—Tznia variabilis Fig. 63.—Tetrarhynchus
from the snipe. from the snipe. appendiculatus from
(Crown of hooks.) the plaice.

with the plate (Fig. 68) of a Tetrarhynchus which. is
usually found in the plaice. The perfect tetrarhynchi,
that is to say, those that aré adult and sexual, inhabit
the intestines of voracious fishes, especially of the
squalide.

There are other worms which migrate, and even some
articulate animals; but their modifications of form are
much fewer than in the preceding, and their changes are
generally restricted to simple metamorphoses. We will
place at the head of this chapter the Linguatule, which
have so perplexed naturalists.

We sometimes find in the nasal fossx of the dog and
the horse a worm resembling a leech, with a body
completely etiolated, which lives there entirely as a

TRANSMIGRATIONS AND METAMORPHOSES. 231

parasite, and whose history has only been known for
afew years. Chabert discovered the first species of this
group in 1787 in the frontal sinus of the horse and
the dog. It had been named Tenia lanceolata. All
naturalists, Cuvier included, placed this animal among
intestinal worms, under the name of Linguatula or
Pentastoma. The latter name had been given to it,
because they mistook the hooks for mouths.

We have shown, from the embryos, in 1848, that
the Linguatule, instead of being worms, are articulate
animals, more allied to the lerneans or acaride than
to the helmintha. These observations, though received
at first with much hesitation, were fully confirmed after-
wards, especially by the learned researches of Leuckart.
The linguatule have a very long body, sometimes
rounded, in other casés compressed, with a mouth
surrounded by four strong hooks, regularly disposed in
a semicircle. They have often been found in the lungs
of serpents, in certain birds, and in many mammals. A
linguatula was also seen by Bilharz at Cairo, in the
liver of a negro, and they have been observed in the
hospitals of Dresden and Vienna.

It is to be presumed that this dreadful parasite has
been introduced into man by means of the flesh of
the goat, and perhaps of the rabbit. Linguatule
are found in their primary agamous form, in open
cavities like the nasal fosse. Leuckart was the first
to show that the linguatule, which lived at first
encysted in the peritoneum of the rabbit, completed their
evolution and became perfect in the nasal fossw of
the dog. The Linguatula serrata (Fig. 65), which lives
primarily in the goat, the guinea-pig, the hare, the

932 ANIMAL PARASITES AND MESSMATES.

rabbit, &c., is found accidentally in man, and perfect in
certain mammals. Examples have been given of sick
persons being completely cured by the evacuation of
worms from the nostrils; these worms were, doubtless,
linguatule. Fulvius Angelianus and Vincentius Alsarius
speak of a young man who had suffered for a long time
from head-ache, and
who passed a worm
from his nostrils. It
was as long as the
middle finger. There
is little doubt that this
was the Linguatula

Fig. 64.--Isolated hook of Fig. 65.—Linguatula magnified six times. Four
Linguatula. hooks are seen around the mouth in front.
c, the anus.

tenioides. These parasites may perhaps sometimes lose
their way in their peregrinations. Some years ago a
lioness died of peritonitis at Schénbrunn, and, after
death, the liver, the spleen, and other organs were
found to be filled with encysted linguatule. ,
The nematode worms are long and rounded, like the.
ordinary ascarides of infants, which take up their abode
in all the organs of animals of the various classes of the
animal kingdom. About a thousand varieties are known,

TRANSMIGRATIONS AND METAMORPHOSES. 288

varying in length from a few millimétres to forty or
fifty centimétres.

They are not all parasites, as has been thought,
since some are found in the sea, and others in damp
earth, in putrid matter, and even on plants and their
seeds. The migrations of nematodes are subjects of
great interest. Their changes of form are usually not
very considerable; but the modifications in their sexual
apparatus, whether in the same individual, or in the
succeeding generations, are very curious.

When we consider the numerous encysted and
agamous nematodes, which are found in the different
orders of mammalia, birds, reptiles, batrachians, and
fishes, there is little doubt that all these beings are only
migratory parasites, which pass together with their hosts
into the animal to which they are destined. They are
found, like ascarides, in animals of all classes. Some
are to be met with in all the organs—the brain, the eye,
the muscles, the heart, the lungs, the tracheal artery,
the frontal sinus, the digestive tube, the skin, and even
in the blood. Sometimes the two sexes live under the
same conditions ; sometimes the male is dependent on
its female, or else one generation is parasitical, and
the next is independent. There is a great diversity with
respect to development. Some nematodes, like trichina,
are developed so rapidly, that the embryos are already
perfect in the egg before it has quitted its mother.
Others, like the ascarides lumbricoides, lay eggs, in
which the embryos do not appear till several weeks or
many months after they have been laid. Between these
two extremes we find all the intermediate degrees.

Diezing, who has done more for systematic helmin-

234 ANIMAL PARASITES AND MESSMATES.

thology than any other naturalist, brought together,
under the name of Agamonema, all the migratory
agamous nematodes which wait for the opportunity of
entering their final host. Diezing had kept himself
quite independent of the discussion by fixing his atten-
tion exclusively on form, without taking account of
migration and digenesis. One of these agamonemata,
lodged in the midst of a pediculated cyst on the vagina
of a bat (the little horse-shoe), was probably a worm that
has lost its way; if not, we must admit that these
mammals become the prey of some carnivorous animal.
But what carnivore can habitually feed on the cheirop-
tera? There are but few fishes, either in fresh or salt
water, which do not enclose in the folds of their perito-
neum, especially round the liver, cysts full of these
agamonemata. :

We see in some of the nematodes examples of migra-
tion which are quite peculiar to them. Some of these
worms are always free, others free at one part of their
life only, others migrate from one animal to another;
others again from one organ to another. The Ascaris
nigro-venosa of the frog lives sometimes in the lungs, at
others in the rectum or quite out of the body in damp
earth. The Filaria attenuata lives in the rook (Corvus
Frugilegus), and it is said that it becomes sexual in the
intestines of the same bird.

These worms are usually very tenacious of life;
many of them can, it is said, be dried for weeks, months,
or years together, and return to life as soon as their
organs are moistened. Their eggs resist even the action
of alcohol and the most active chemical agents, and eggs
that had been prepared for the microscope, and had

‘

TRANSMIGRATIONS AND METAMORPHOSES. 285

served for many years the purposes of study, have been
known to produce young ones as if they had been just

laid.

Natura non facit saltus is especially true as to the
division of sexes among the nematodes. Between the
true hermaphrodites and the true diccious worms are
found species in which the males gradually dwindle and
become dependent on the female; this is to be seen in
the Spherulariw, among which the male is only an
appendage to the female sex. We find here full evidence
of the fact that the female is more important than the
male, with regard to the preservation of the species. In
some species the sexes differ but little; in others, the
sexual differences become greater, and the male is only
one third of the length of the female; but in some of
them the disproportion is greater still. At the same
time, we see nematodes whose males are attached to the
females, so as only to form a single individual; in other
cases, the male seems to disappear to such an extent,
that we find nothing but the male organ in the female ;
indeed, there are instances of male worms, which, with-
out changing their form, occupy the cavity of the matrix
and, like the lernean crustaceans, are parasites of their
females. The Trichosomum crassicauda is an instance of
this kind.

Arrangements which would not have been suspected
beforehand, are every day revealed, with respect to the
conservation of species. We have recently learned from
the works of Messrs. Malmgren and Ehlers, and later
still, from those of Claparéde, that in the same species
we may find different males, producing different off-
spring. Messrs. Malmgren and Ehlers have opened this

236 ANIMAL PARASITES AND MESSMATES.

question by their persevering researches, and Mons.
Claparéde expected to invalidate the results obtained by
them by establishing himself at Naples, in order to
devote himself to a new series of investigations. Contrary
to his expectations, he arrived at the same conclusions,
and announced that a nereid possesses, in one and the
same species, two kinds of males and two sorts of
females, and that these males differ from each other,
not only in their manner of life but in their age, in the
mode of formation of the spermatozoids as well as in
the form; that the females differ no less from each
other than the males, and that each form is intended to
provide, in its own manner, for the dissemination of the
eggs.

We see this realized in annelid worms known by the
name of Heteronereide. Certain individuals of small
size live on the surface of the water; others, evidently
much larger, live at the bottom -of the sea and behave
quite differently. The eggs and the spermatozoids pro-
ceeding from. these two forms differ sensibly from one
another, and the difference of form corresponds with
that of origin. ,

We see thus among some of them different males;
among others different females: then eggs and sperma-
tozoids equally different in one and the same animal
species.

A curious insect, the Termes lucifuga, appears also to
distinguish itself by two. sorts of males and females,
which even take to flight at different periods. Great
sagacity was required to reveal these strange facts.
Mons. Lespes has had the courage to devote himself
to these observations.

TRANSMIGRATIONS AND METAMORPHOSES. 237

We see that all means are good that are for the
preservation of the species, but who would have suspected
that in a single animal there would be found two males
by the side of two females, neither of which resembles
the other, and besides these, two kind of eggs and sper-
matozoids! How great would be our astonishment
were we to see two. sorts of cocks, two kinds of hens,
and two sorts of eggs produced by the same mother,
and hatched at the same time!

Professor Hrcolani bred in damp earth certain para-
sitical nematodes, kept them alive, saw them reproduce,
and was even able to obtain several generations of them.
These nematodes were the Strongylus filaria from the
lungs of the goat, the Strongylus armatus from the in-
testines of the horse, the Ascaris inflexa, and the
Ascaris vesicularis from the fowl, and the Oxyuris in-
curvata from the horse. The first three, whether they
are born in damp earth, or in the midst of organs in
which they habitually lodge, have the same external
characters; nothing is remarked in them except a greater
activity in their reproduction.

The Strongylus armatus, when born at liberty, appears
no longer to have hooks at the mouth like those worms
which live in the intestines. Mons. Ercolani has also
remarked that these worms, when they become free, are
ovo-viviparous, though they were before oviparous.

There are many of these nematodes which are true
parasites of man, and although certain of these are as
much dreaded as the plague or the cholera, we are far
from knowing all their history, and especially the manner
in which they are introduced.

A young naturalist, Dr. O. Bitschli, has lately made

238 ANIMAL PARASITES AND MESSMATES.

a good résumé of the state of our present knowledge of
parasitical and wandering nematodes.

The Sclerostomata are distinguished by their mouth
being surrounded by a horny armature. The river .
perch usually gives lodging to a viviparous nematode,
the Cucullanus elegans,.on the development of which a
special work has been published. .The young ones are
provided with a perforating stylet, and penetrate into
the bodies of small aquatic crustaceans, called cyclops.
When ‘they have obtained entrance into this living
lodging, they bore through the walls of the intestines
and shut themselves up in the perigastric cavity. The
cyclops being pursued by the young perch, are swallowed
with their guest, and the latter is set free in the midst
of the stomach, where it passes through its sexual
evolution.

Leuckart saw in his aquarium young Cucullani
penetrate into the bodies of the cyclops. These crus-
taceans are therefore the vehicle of these nematodes. An-
other nematode worm, the Dochmius trigonocephalus, lives
at liberty while young, but seeks for an asylum in the dog
in its old age. The Sclerostomum equinum causes aneu-
risms in the horse, which manifest themselves by colic.
A hundred of these worms have been found in the same
horse. The Sclerostomum pinguicola is very common in
the pig in the United States. This is the Stephanurus
dentatus of Diezing, noticed by Natterer in Chinese pigs
in Brazil. Cobbold notices the same worm as living in
the pig in Australia; they have been also found in
Germany.

The Strongyli are round, cylindrical worms, with
bodies sometimes entirely red, which inhabit different

TRANSMIGRATIONS AND METAMORPHOSES. 239

organs in mammals and birds. A very remarkable
species, the Strongylus gigas (Fig. 66), exists in the

Fig 66.—Strongylus iiiptii—t, dette: showing a, the mouth; J, the intestine; ¢,
genital pore; d, anus. 2, ceplialic extremity of the male; a, mouth; 0, wso-
phagus. 3, caudal extremity of the male ; a, cup; 8, penis. 4, egg.

kidneys of the horse and the dog, and sometimes in

man. It partly destroys this organ, and has been seen

a métre in length. The Strongylus commutatus often

lives in great abundance in the lungs of the hare, and

the Strongylus filaria in the lungs of the sheep, occa-
sionally in such great numbers that their presence
produces pneumonia.

Porpoises generally have strongyli in their lungs and

their bronchia, and they are seen by thousands in the
12

\

240 ANIMAL PARASITES AND MESSMATES.

sinus of the Eustachian tube. We collected a large bottle
full from a single porpoise around its internal ear.
When we consider the prodigious number of these
creatures, may we not suppose that they are able to
multiply in the organs which they occupy, as well as
migrate to infest other individuals.

Different generic and specific names have been given
to these Strongyli. A round worm found in the intestines
of the dog, the Strongylus trigonocephalus, lives at first
in damp earth or mud like
the rhabdites in general;
it then passes into the’
dog, and there becomes a
sexual Strongylus. It is
possible that there are
others in the same cate-
Bory: ; AA

The Ascaris lumbrico- ali
ides is a large round worm
which attains the size of
a quill pen, and which is
commonly found in the
stomach or the lesser in-
testines of children when
in good health. Aristotle
was acquainted with it.
It has been observed
throughout Hurepe, in “Fao os eee aL,
Central Afri ca, in Brazil, 4, middle of the body of female,
and Australia. The same species lives in the intestines
of the pig; but the Ascaris megalocephalus, which is
usually found in the horse, is of a different species. _

F
E
=
a

@RANSMIGRATIONS AND METAMORPHOSES. 941

The Ascaris acus of the pike lives at first in a common
white fish, the Leuciscus alburnus, and passes with this
fish, which serves it as a vehicle, into its final host.

Another common nematode, the Oxyurus vermicularis
(Fig. 69), a parasite of man, is a small worm of the size
of a fine pin, which often multiplies in the rectum of
children, causing intolerable itching. It is by means of
their microscopic eggs that they penetrate into the
system; these are hatched in the stomach, and are com-
pletely developed at the end
of eight or ten days. They-
pass from the anus in great
numbers.

=
=
I
ze
==
z=
4
#2
==
34
3=
22

Fig. 68.—Trichocephalus of man.—1, female, Fig. 69.—Oxyurus vermicularis. —1, male of

a, cephalic extremity, b, caudal extremity natural size, 2, female, id., 8, cephalic
and anus, ¢, d, digestive tube and ovary, extremity, magnified.
e, orifice of sexual apparatus. 2, isolated
egg. 3, male, a, cephalic extremity, d,
anus, c, digestive tube, @, spicula or penis,
e, sheath into which it is withdrawn.

The brood of worms from the eggs of the Ascaris
megalocephala of the horse live in freedom, and go
through all their phases until their sexual develop-
ment separately; there are males and females. The

242 ANIMAL PARASITES AND MESSMATES.

generation which descends from these is distinguished
by being of a much smaller size.

The name of Trichocephalus has been given to nema-
todes which have the cephalic extremity very thin, and.
ending in such a fine point that it is difficult to discover
the mouth. The Trichocephalus of man (Fig. 68) is a
curious nematode, which was discovered by a student at
Gottingen, in 1761. It is usually found in the cecum,
in which more than a thousand have been met with
together. The female is from 40 to 50 millimétres long,
the male about 37 millimétres. A female Trichocephalus
afinis having laid her eggs in an aquarium, the whole of
the contents were introduced into the stomach of a lamb,
seven months afterwards, and the walls of its intestines
became infested with trichocephali.

-No animal at any time has attracted so much atten-
tion as that little worm which lives in flesh, rolled up;
it is about the size of a millet seed, and was found by
chance in the dissecting-room of a London hospital, some
forty years ago. The plague and the cholera did not
inspire so great fear, and this fright had almost passed
from Germany throughout the rest of Europe. We were
not among those who wished to take measures at all
hazards against the invasion of this worm, since nothing
induced us to believe that more trichine existed then
in Belgium than in ordinary times. These measures
would have produced no other effect than uselessly to
disturb the minds of the public.

Trichiniasis, which was the name given to the disease
caused by these worms, reminds us of tarantism, that is
to say, the effects produced by the bite of the tarantula.
Mons. Ozanam wrote an interesting work on this subject,

TRANSMIGRATIONS AND METAMORPHOSES. 243

in which he said that nervous tarantism existed during
two centuries in Europe, as an epidemic malady.
According to him, there pre-
vails at present in the province
of Tigre, in Abyssinia, a sort
of chorea, or endemic musico-
mania, which has a great ana-
logy with tarantism ; it is the
“Tigretier.”” Nothing but music
and dancing can have any
beneficial effect during the
crisis; but these means would
evidently be inefficacious in
trichiniasis.

The Trichina is a nematode
worm, and not an insect, as
it was at first called. Let us imagine an extremely
slender pin, such as entomologists employ to fasten the
smallest insects, rolled upon itself in a spiral form so as

i i io v a TH HATE an Hn ity
mm i ul ue ile ue i ie i
Ae

Fig. 70.--Trichina.

me oe y gr i il
ap
er ine

io

etn pet
ne

Oe: fl i 1
c ON We as i ie
a Beat h
ith nT ao. cal ra ft il I
ee, ini init fi Cee

Fig. 71.—Trichina, rolled up in a muscle.

to lodge in a cavity hollowed out in the midst of the
muscles, in a space not larger than a grain of millet. ~

244 ANIMAL PARASITES AND MESSMATES.

These trichinw of the muscles can be discerned by the
naked eye. But before we enter on a particular descrip-
tion (and they are now known in their minutest details),
let us notice what were the circumstances which led to
their attracting so much attention.

It was in 1882; a demonstrator of a course of
anatomy at Guy’s Hospital in London, Mr. J. Hilton,
found in the flesh of a man sixty-six years of age, who
died of a cancer, a great number of little white bodies
which he took for vesicular worms. The scalpel, during
the dissection of the muscles, met with granulations
which blunted the edge of the instrument. Astonished
to find in the flesh hard corpuscules which the instru-
ment divided with difficulty, he removed some of them,
examined them attentively, but, no doubt, he was not
sufficiently acquainted with helminthology to understand
their true nature, He referred to Professor R. Owen,
the celebrated naturalist of the British Museum, who
recognized them as new worms, and gave them the
name of Trichina, because they are as thin as a hair;
he added the specific name of spiralis on account of the
manner in which they were rolled up in their cyst.
Trichina spiralis is therefore the name of this animal.

Some naturalists, at that time, believed that the
filaments of the fecundating fluid of the male were
parasitical worms, such as are found in other liquids;
and these filaments which were designated by the name of
spermatozoids (the animalcule of the older naturalists),
were considered as beings havigfg a certain affinity with
trichinw. The trichine were the intermediate state
between these filaments of the fecundating fluid and
worms properly so called. It is now known with

TRANSMIGRATIONS AND METAMORPHOSES. 245

certainty that these filamentary bodies are no more
animals than the globules of blood, and that all that
was thought to have been observed of their organization
was nothing but pure fancy.

The trichine, which are now completely known in
the minutest details of organization and manner of life,
have a distinct mouth, and they have a complete
digestive tube with an orifice at each end of the body,
like all worms in the form of a thread, which, for this
reason, are called by naturalists Nematodes as opposed
to Cestodes (in the form of a ribbon or tape). Besides
this nutritive apparatus, trichinw, like nematodes in
general, have the sexes divided into two distinct indi-
viduals, so that there are males and females, which
can be easily distinguished from each other by the size
and form of the body.

Triching are found in the flesh of almost all the
mammals. If we eat this trichinous flesh, the worms
become free in the stomach as digestion goes on, and
they are developed with extreme rapidity. Each female
lays a prodigious number of eggs; from each of these
comes a microscopic worm, which bores through the
walls of the stomach or the intestines, and thousands of
trichine lodge themselves in the flesh, where they hide
till they are again introduced into another stomach.
When the number is great, their presence may cause
disorders or even death. lLeuckart’s experiments on
animals aroused the attention of physicians, and then it
was found that patients who had shewn exceptional
symptoms, had fallen victims to the invasion of these
parasites. Leuckart counted 700,000 trichine in a
pound of the flesh of a man, and Zeuker speaks of

246 ANIMAL PARASITES AND MESSMATES.

even five millions found in a similar quantity of human
flesh.

The Trichina spiralis produces about a hundred young
worms at the end of a week (viviparous); and a pig
which had swallowed a pound of flesh (5,000,000 tri-
chine) might contain after some days 250 millions,
reckoning that only half the worms hatched were
females, which is not the case, for there are more females
than males. It appears that trichine can become sexual
in all warm-blooded animals, but the number in which.
they can become encysted is not so great. It appears
that they are not encysted in birds.

In the month of December, 1863, R. Leuckart wrote
to me from Giessen ; ‘“‘ The Trichine are playing a great
part at present in Germany (with the exception of
Schleswig-Holstein). Two epidemics have made their
appearance within a few months, and have produced
a veritable panic, so that no person will any longer eat
pork. The authorities everywhere are obliged to subject
the flesh of these animals to microscopic examination.”

We owe to Leuckart (1856 and 1857) and to Virchow
(1858) the knowledge of the principal facts of the history
of these worms. Virchow ascertained by experiment
that they become sexual in the alimentary canals at the
end of three days ; and these two naturalists discovered,
after many researches, that trichine are neither strongyli
nor trichocephali, but a different kind of nematode,
which are hatched in the stomach of those whom they
infest, and that their embryos, instead of migrating,
establish themselves in the host himself. The embryos
of parasites do not usually remain in the animal which
gives them lodging; they are evacuated, as well as the

TRANSMIGRATIONS AND METAMORPHOSES. 247

eggs, and are conveyed to another animal. The trichine
are sexually developed in the same animal in which they
have been engendered.

Worms which produce eggs do not usually hatch
them in the same animal; they are evacuated with the
feces. The trichine are an exception. These agamous
worms, when introduced into the stomach, rapidly pass
through their evolutions there, become sexual, lay eggs,
and the germs which are produced from them ‘pierce the
tissues, and become encysted in the muscles or other
closed organs. It appears that the Ollulanus tricuspis, a
nematode of the cat, presents the same phenomena. It
is a species of trichina, which lives at first in the
muscles of the motise which serves it as a vehicle, then
in the stomach of the cat, where it becomes sexual and
complete.

The Spiroptera obtusa is a worm remarkable for its
peregrinations. It passes with the excrements of the
mouse into the larva of Tenebrio molitor, which is very
fond of it. At the end of a month it is encysted in this
insect, and after five or six weeks it becomes sexual in
the mouse. The Spiroptera obtusa of the mouse lays
eggs which are evacuated with the feces; and these
become, with the eggs which they enclose, the prey of
meal worms, the larve of the Tenebrio molitor, a coleop-
terous insect. These germs come forth in the intes-
tine of the larva, they perforate the intestine and
become encysted in the folds of fat which surround it.
Some fine day the insect is swallowed by the mouse, and
the Spiroptera, set at liberty in the intestine, will be
gradually matured until its sexual development is

complete.

248 ANIMAL PARASITES AND MESSMATES.

The ordinary crab of our coasts, Carcinus menas, is
the vehicle of a nematode which becomes a Coronilla
robusta in the stomach of a ray.

The Heteroura androphora is another nematode which
lives in the stomach of tritons. The male is always
rolled round the body of its female. The two sexes are
always free, contrary to that which is observed in the
syngami. The Blattz, coleopterous insects, also harbour
sexual nematodes. Radkewisch saw two species of an-
guillule, the Anguillula macroura and appendiculata, in
the Blatia orientalis, and an Oayuris brachyura in the
Blatta germanica. These eggs leave the body with the
feces, and resist the action of deleterious agents.

Heterodera Shachti is the name given to a nematode
which Mons. Schacht discovered on beet-root. This is
also a dimorphous worm ; the male has the usual form,
the female resembles a lemon. The Lepiodera appen-
diculata inhabits the foot of the Arion empiricorum, in
the larva state, and becomes sexual (male and female)
in the decomposed body of the snail. The next genera-
tion has the sexes united, and lives in damp earth. The
Leptodera pellio lives in the same way in the bodies ot
lumbrici; another Leptodera inhabits the intestine of
the snail, and a third the salivary glands. The ne-
matode so generally known under the name of Ascaris
nigro-venosa also belongs to this genus. It lives in the
lungs of the frog. There is one also in the lungs of the
toad, but it differs from the preceding.

Leuckart looks upon these worms as females, and
their reproduction as parthenogenetic. Schneider con-
siders that the male exists by the side of the female sex,
and that they are consequently hermaphrodites. These

TRANSMIGRATIONS AND METAMORPHOSES. 249

worms in the lungs are viviparous, and embryos are
found in the midst of the intestine of the same animal
which gives lodging to the female. These same worms,
proceeding from an hermaphrodite parent, or from par-
thogenetic females, live at liberty, and not parasitically
in damp earth or in a decomposed body, and differ from
their parents in size as well as in sexual organs. They
all become either male or female, and consequently their
fecundity is dependent upon copulation. Their parents
could all multiply without it, but they cannot. The
females alone produce a new generation.

A worm known by the name. of Vibrio anguillula lives
in grains of corn while still green, and multiplies there
to a prodigious extent; it is this which causes the
disease known by the name of smut. The grains grow
hard, and enclose nothing but little dried worms, which*
remain thus without apparent life, yet without dying,
until they are moistened, when they become damp,
the tissues swell, the organs resume their natural
appearance, and the functions are restored at the end of
a few hours.

In a grain of corn affected by smut, anguillule
without distinct organs are found, which may be dried
and revived eighteen times in succession, according to
Mons. Duvaine, who thinks that these anguillula, leaving
an infected grain, come out of their envelopes in a field
of corn, cling to the young stalks, and rise with them.
They begin to develop themselves in the rudimentary
flower of the corn, and acquire genital organs like
nematodes. Males and females are always found sepa-
rately in a grain of corn.

The ermine lodges in its lungs and tracheal. artery

250 ANIMAL PARASITES AND MESSMATES.

a long worm, to which I have given the name of
Filaroides mustelarum. It usually forms a little sac,
which resembles a tubercle. Many individuals of
different sexes, wound round each other, are so closely
tied together that they can with difficulty be separated.
They resemble a ball of cotton. This filaroid sometimes
gets into the frontal sinus, and mechanically destroys
a part of its osseous walls, so that the skull is pierced.
by a hole above the frontal sinus. Dr. Weyenberg made
this observation.

It is probable that other species ot Mustela will
present the same phenomena, for the skulls of this
animal are often to be found perforated above the
orbital cavity.

The Ollulanus tricuspis is a worm which lives in the
walls of the stomach of cats; it is viviparous, and the
young ones sometimes wander into the muscles of their
host. But the natural course of things is that the
young are evacuated. with the feces, and that these
dejecta, according to all probability, form part of the
food of mice, and pass with them into the cat. It is
to be hoped that Leuckart will soon put this migration
out of doubt by a decisive experiment, and will prove
that the mouse serves as a vehicle for three different
worms, the Cysticercus, the Spiroptera obtusa, and the
Ollulanus tricuspis.

Many nematodes lodge in the substance of the walls
of the gizzard of birds. In the large goosander we have
found one which has round its head four blades, crossing
each other, toothed on the concave side. We have given
the name of Ascaracantha tenuis to this worm. It has
very small eggs. The Trichosomum crassicauda is a

TRANSMIGRATIONS AND METAMORPHOSES. 251

nematode of the rat; the female is 2°5 millimétres in
length, and the male ‘17 millimétres, and it lives in the
uterus of its female. Five males are occasionally found
in one female. This observation made by Leuckart has
been confirmed by Butschli. The male has its digestive
tube incomplete; its female feeds for it.

The bat of the high mountains of Bavaria, known
under the name of Vespertilio mystacinus, harbours a
nematode, the Rictularia plagiostoma, the same which is
found in Egypt in the hedgehog (Hrinaceus auritus).
The bat on the banks of the Rhine has not this
remarkable worm. We must therefore conclude that
the bat of Bavaria finds and eats the same insect as the
hedgehog in Egypt, and that this insect does not live on
the banks of the Rhine. We have never met with this
nematode in the mystacines of Belgium, and yet we have
opened them by hundreds.

A bird found in Florida, the Anhinga, has in its
brain a nematode whose presence in that organ is not
accidental.

The Echtnorhynchi form a very remakable group of
parasites. They migrate from one host to another ; but
the vehicle by which the greater part of them is con-
veyed is not known. We represent in Fig. 72 a species
which is very common in the intestine of the sprat.

It is known that these worms migrate when young,
and undergo metamorphoses when they change their
host. The Asellus aquaticus of fresh water, harbours
besides other worms, the Echinorhynchus heruca; the
Gammarus pulex, another fresh-water crustacean, lodges
the larva of the Hchinorhynchus proteus (Fig. 72). We
commonly find this beautiful species of the Echino-

252 ANIMAL PARASITES AND MESSMATES.

rhynchus in the alimentary cavity of the sprat, and it
is easily distinguished by its peculiar form and its
orange colour.

Fig. aia a proteus Fig. sree jee le in

The ‘Asellus aquaticus seems also to serve as the
vehicle of the Echinorhynchus angustatus. The hooks of
the embryos differ from those of the adults, as the six
hooks of the cestodes differ from the crown of the adults.
Leuckart has described those of the envelope of the
Echinorhynchus proteus and the Echinorhynchus angus-
tatus. The embryo of the Echinorhynchus has only two
large hooks on each side, but several smaller ones. The
two species mentioned above have on each side five or
six hooks placed at right angles with the median line,
but they are not all of the same size.

The animals are allied to the Gordii in their develop-
ment. In fact, their development is like that of the
echinodermata ; the larva is the Pluteus, in which the true
echinorhynchus develops itself, borrowing the skin of the
pluteus. According to the experiments made by Schneider,
the larve of cockchafers must be the vehicles of the

TRANSMIGRATIONS AND METAMORPHOSES. 258,

Echinorhynchus gigas. Pigs disseminate the eggs, and the
embryos infest these larve, in the bodies of which they
pass through their principal changes.

The Gregarine are microscopic beings, with an
extremely simple organization, the nature and the
genealogy of which have only lately been known. They
live at first encysted by thousands together, under the
name of Psorospermiw; they are afterwards hatched in
the form of Amebe#, and then transformed into Gregarineg.
They migrate from one animal to another, or from one
organ to another, to settle in the intestine, where they
assume their adult form. In this state they are mono-
cellular, and do not at any time possess organs which
resemble the sexual organs of other classes. The disease
of silk worms, known by the name of “ pebrine,” has
been attributed to the development of psorospermiz.

We give the representation (Fig. 74) of gregarine
which we have found abundantly on the Nemertes; and

Fig. 74.—Gregarine of Nemertes Fig. 75. — Stylorhynchus oligacanthus, from the
Gesseriensis. larva of the Agrion.

(Fig. 75) a peculiar species which lives in the larva of an
agrion.

254 ANIMAL PARASITES AND MESSMATES.

We also give a sketch (Fig. 76) of some very remark-
able parasites, whose affinities are still problematical,
_and which only inhabit spongy bodies, such as the

Fig. 76.—Dicyema Krohnii, from Sepia officinalis.

kidneys of cephalopods. The name of Dzcyema has
been given to them.

Prof. Ray Lankester has quite recently made some
very interesting observations, at Naples, on these pro-
blematical beings; and my son has just devoted a part
of his vacation, with two of his pupils, to elucidate the
points of their organization and development, which are
still obscure. He went to reside at Villefranche, near
Nice, in order to obtain fresh cephalopods every day.
His observations have led him to a result quite different
from that which I expected.

CHAPTER X.
PARASITES DURING THEIR WHOLE LIFE.

In this chapter we bring together true parasites, which
may be called complete; they pass every part of their
life under the care of a neighbour, and require an asylum
the more urgently, since they cannot exist without it.
They absolutely need both food and lodging. Not long
ago, all parasites were supposed to be dependant during
their whole life, and to be incapable of living outside the
body of another animal. We have before proved that
this opinion was erroneous. We find in this category a
great number of parasites which may be separated and
placed in the first group, including all such as pass all
the phases of their life on the same animal, without
changing their costume, and many of which never leave
the fur, the feathers, or the scales, among which they are
born.

Fishes nourish on the surface of the skin a great
number of these, which helminthologists have thought
proper to classify under the name of LEctoparasites.
Among many crustaceans and insects, only one of the
sexes is parasitical. The males remain entirely free,
and preserve all their attributes, while the females seek
for assistance, and require food and lodging. The female

256 ANIMAL PARASITES AND MESSMATES.

alone sacrifices her liberty, and changes her form entirely
in order to secure the preservation of her posterity.

The insects called Strepsiptera, which live as parasites
on wasps, furnish a curious example of this (Fig. 77).
These insects, the Polistes, the Andrene, and the Halicti,
do not kill the larve of the Hymenoptera on which they
feed; they suck the blood of their victim slowly, and
leave him just enough strength to go through his meta-
morphoses. The females. are condemned to remain
almost completely immovable on their prey, while the
males are winged.

Naturalists have paid great attention to these latter
insects, as much on account of their mode of life as of the
difficulties which they have suggested to entomologists in
the appreciation of their natural affinities. Are they
coleoptera, as was for a long time, and perhaps correctly,

supposed, or do they

form ‘a distinct order

= _\ by themselves? How-
ever this may be, these
are the facts known
concerning them, ac-
cording to the recent
observations of Mons.
Chapmann, a _ con-
scientious naturalist.
7) The females do not

Fig. hes SAUDE. an size, and lay their eggs in the
nests of wasps, but the

larve, under the form of meloé, penetrate into the cells,
by the assistance of the larve of the wasps, which carry
them hidden between the second and third ring. The

PARASITES DURING THEIR WHOLE LIFE. 257

larve of the Rhipiptera are developed at the expense of
the larve of the wasp, suck their blood, swell, and their
skin remains adhering to the fourth segment.

ig. 78.—Black Stylops, female, showing Fig. 709.—Black Stylops, larva at its
a the embryos 1s the abdomen. birth (from B) anchard).

When the rhipipterous insect is six millimétres in
length, it changes its skin the second time, and this

258 ANIMAL PARASITES AND MESSMATES.

splits on the back, so that the skin remains fixed between
the larva of the parasite and that of the wasp. It then
sucks the rest of the juices of the young wasp, and
becomes a nymph in the prison which it has formed for
itself. This evolution lasts from twelve to twenty-four
hours.

Many male crustaceans, though they differ materially
from their females in form as well as in manner of life,
do not remove far from their partners in order to procure
the assistance which they need. The insects which
now occupy our attention are entirely different in this
respect. The male preserves his usual appearance
during the whole of his life, as well as the attributes
and independence of free insects; while the female
seeks for assistance with regard both to food and lodg-
ing from the time she leaves the egg; she is still
wrapped up in swaddling clothes when she receives the
male, as when she came forth from the egg.

The worms of this category are usually fully formed
without undergoing metamorphoses; and if the place
which they choose at their exit from the egg is not pre-
cisely their cradle and their tomb, at least all the phases
of their monotonous life occur around it. They may
be ranked among the most beautiful and the largest of
parasitical worms; and as they are hermaphrodites, we
find no greater diversity in the several forms than in
their differences of age. All have their reproduction
certain, and their eggs are less numerous for this reason.
There are some of them that lay only one ege at a time,
and this egg sometimes appears but once during a
season. This explains why the eggs of some of these
worms have not yet been recognized.

PARASITES DURING THEIR WHOLE LIFE. 259

We may place at the head of this group the Tristomum,
which has only been discovered a few years. We owe
to Baster the knowledge of a beautiful and large species,
which inhabits the body of the halibut. Naturalists
have given it the name of Epibdella. This worm is of
the size of the human nail; it resembles in form a box
leaf; by the aid of its suckers it clings to the skin of its
host like a scale; and is sometimes mistaken for one.
It is of an oval form, and of a dull white colour; it can
searcely be distinguished from the skin of the fish. We
‘may have it before our eyes for a long time before we
perceive it. ,

Another Epibdella lives on the skin and on different
parts of the body of the European maigre, or the Virgin
Mary’s fish; it is covered with pigment spots which
cause it still more to resemble the large scales of its host.
This fish, which is also called the Sciena aquila, has its
skin covered with similar scales, and they are of the
game colour, both on the back and belly.

Another large and fine worm of this group lives on
the gills of the sturgeon, and is distinguished by its
suckers as well as by its great mobility. The epibdelle
preserve their scale-like form during their greatest con-
tractions, but these worms change with every movement.
The Nitschia elegans, for such is the name by which it
is distinguished, is not rare on the sturgeon as we see
it in our markets. Among the many parasites in this
category, there is a very remarkable one which deserves
particular mention. It lives abundantly on fresh-water
fishes, preferring to attach itself to their gills; it is found
most commonly on the bream. For our knowledge of
these worms we are indebted to Nordmann.

260 ANIMAL PARASITES AND MESSMATES.

They bear the name of Diplozoon paradoxum, and are
always double, that is to say, always united like Siamese
twins, being organically fastened together; they leave
the egg, like their congeners, isolated and hermaphrodite,
instal themselves separately on their host, and a little
time after their choice of a resting-place, they unite so
that the tissues, I was about to say the organs, are
welded to each other. They cross like two strokes of an
x. It is in this position that they live and die, after
having produced large and beautiful eggs provided with
a very long cable. These eggs are laid separately, and
attached to the gills of the fishes which give them
shelter. At the end of a fortnight the ciliated embryo
comes forth, being provided with two eyes, and seeks to
establish itself on a fresh host.

Under the form of Diporpa it has a ventral sucker,
and a small papilla on its back, and the two individuals
are attached to each other cross-wise by the sucker and
the papilla. Notwithstanding what Humboldt says in
his ‘‘ Cosmos,” the Diplozoon is not an animal with two
heads and two caudal extremities, but is a double animal,
two hermaphrodite individuals united, which at first
have lived separately, and have become soldered to each
other at the period of maturity.

We find a nematode, and consequently an animal
with the sexes separate, which presents the same phe-
nomena. The male and female are soldered together,
but the female alone undergoes development. It is the
Syngamus trachealis of Siebold. It inhabits the tracheal
artery of some gallinaceous fowls, and according to
recent experiments, it develops itself directly in the
tracheal artery of birds.

PARASITES DURING THEIR WHOLE LIFE. 261

Another beautiful trematode, the Octocotyle lanceolata,
lives abundantly on the gills of the alosa, and another,
the Octobothrium merlangus, on those of the whiting.
The gills of the Mustelus vulgaris regularly bear another
species resembling a leech, but instead of a single sucker
there are six; this is the Onchocotyle appendiculata.

The bladder of frogs lodges a very beautiful and large
trematode which has lately been studied by many
naturalists, the Polystomum integerrimum. Many obser-
vations remain to be made on the different phases of the
existence of this parasite. Its organization is known,
and it has been seen to lay large and beautiful eggs, but
its movements have not been observed before its en-
trance into the bladder.

This Polystomum of the frog—and it is no doubt
the same with the species Polystomum ocellatum which
inhabits the mouth of the European tortoise (Hmys
Europxa)—lays eggs only in winter, and the eggs of the
young ones do not seem to produce more precocious
embryos than those of the adult. The embryos are
ciliated, unlike those of many of the ectoparasite worms.
They much resemble the gyrodactyles, especially by their
bristles ; and like these, they inhabit the cavity of the
mouth before they migrate into another organ. We may
even ask if these singular gyrodactyles, so peculiar in
many respects, are not the larval forms of trematodes
allied to the polystomum.

Several important works have lately appeared on
the Polystomum integerrimum, by Mons. Stiéda in 1870,
by Mons. E. Zeller and Mons. Willemoes-Suhm in
1872.

The gyrodactyles, which we have just mentioned, are

262 ANIMAL PARASITES AND MESSMATES.

among the most curious worms that have been dis-
covered during late years. They are of small size, and
live in the gills of fishes, often in great numbers, and
move with considerable agility. They are armed with
very variable hooks, which serve to anchor them; and
sometimes a digestive canal and organs of sensation are
found in them.

The Gyrodactylus ae bears within it a young
one which already has hooks, and in this young one,
which is not yet born, we see another generation with
the same organs, so that three generations are thus
enclosed. The daughter is ready at the moment of
her birth to give birth to another daughter. According
to another mode of interpretation, the mother and
daughter are sisters; the elder is found at the peri-
phery, the younger at the centre. These worms are
found abundantly in the gills of the cyprinide, or white
fishes. We have only to scrape gently the surface of the
gills with a scalpel, and thus remove a small quantity of
a mucous substance, place it on a slide of a microscope,
cover it with thin glass,.and examine it immediately with
the compound microscope. We cannot repeat this three
times without finding gyrodactyles.

There are also many insects which live as parasites
on plants, and demand from them both a resting-place
and their food. Almost all the Hemiptera are among
these; we have already mentioned them. The hemip-
tera, which live on the sap of vegetables, are parasites
in the same manner as those which live at the expense
of animals. We ought not to make a difference between
the manner of life of the bugs of plants and those of
animals. It may be said that Providence has placed

4

Ne

PARASITES DURING THEIR WHOLE LIFE. 263

these beings as riders on both the vegetable and animal
kingdoms to restrain them with a bridle. What the

Fig. 80.—Cochineal insect, male (Coccus cacti), natural size and magnified.

gardener does to plants, the aphis has often done before
in order to arrest a too vigorous and rapid growth.

The cochineal insect (Coccus cacti) Figs. 80 and 81,
13

264 ANIMAL PARASITES AND MESSMATES.

originally from Mexico, lives on the cactus nopal as a
true parasite, and furnishes a precious colouring
matter, carmine. This insect has been introduced into

Fig. 81.—Cochineal insect, female. Fig. 82.—Aphis.”

the Antilles, Spain, the Canary Isles, Algeria, and
Java.

Lake is produced by a species of the same genus,
originally a native of India (Coccus lacca).

Aphides (Fig. 82) feed on the sap of plants; they
multiply rapidly without the male insect. Rose-trees,
and more especially their buds, are attacked by a species
of a green colour, of which we give a representation
(Fig. 88).

An aphis, the Phyllowera vastatriz, has, a short time
since, invaded the vineyards, and small as it is, it is
dreaded as a plague which scatters ruin in its path.
According to recent observations this insect has a
double series of generations which precede each other :
the mother type and the tubercular type. But this
. polymorphism seems to be more apparent than real,

PARASITES DURING THEIR WHOLE LIFE. 265

although there is a considerable difference in their
manner of life and of procuring nourishment. Is
this difference the result of the different kinds of food

Fig. 83.—Rose-Aphis. Male and Female.

taken from the roots and the leaves? There is one
thing which may reassure us as to the future attacks of

266 ANIMAL PARASITES AND MESSMATES.

the phylloxera, that Mons. Planchon has just discovered
in America the cat of the phylloxera, one of the acaride,
its mortal enemy; and it is only necessary to multiply
these in order to destroy this terrible pest of the vine-
yards. We thus see that we have only to imitate this
so-called blind Nature, in order that we may arrest a
misfortune against which man is unable to protect him-
self by his own powers.

We will here repeat what we wrote respecting
aphides some years ago. Who does not’ know these
small green bodies, of the size of a pin’s head, coming
like a cloud upon the buds and leaves of the rose
bushes, which shrivel and wither immediately? There
are green ones on certain plants, and black ones on
others, but whatever be their colour, they are living
pearls which form garlands round the stalk. The world
considers them as vermin, and they scarcely dare to
touch them with the point of their fingers. To the
naturalist they are a little world of wonders. Let us
examine with a magnifying lens these walking grains of
sand; each grain will reveal to us a charming insect,
‘whose head is adorned with two little antennzy, and
has globular projecting eyes glistening with the richest
colours; behind these are two reservoirs of liquid
sugar, elegantly mounted on a polished stalk, and
always full; long and slender limbs support the
globular body.

Much has been written about these small sugar
manufactories, so well known by ants that they have
procured for the aphis the name of ant-cow. Among
the curious phenomena presented by these grains of
animated dust, that-which most interests us relates

PARASITES DURING THEIR WHOLE LIFE. 267

to the secret of their astonishing, we may say, their
prodigious fecundity.

Nature requires millions of aphides in a few hours,
to arrest the exuberance of vegetation, and as if she
distrusted the assistance of the male insect, she dis-
penses with it, and the female brings into the world a
daughter already prepared to produce a grand-daughter.
Generations succeed each other with such rapidity,
that if the daughter at her birth were to meet with
any obstacle in her passage, the grand-daughter might
come into the world before her mother; a single egg
can produce in the course of one season milliards of
individuals. Each plant has its own aphis, and in many
localities the ravages of the Aphis laniger are but too
well known, though it was unknown in Europe a
quarter of a century ago.

The Gyrodactylus elegans, of which we have spoken
above, contains embryos similarly enclosed, and if these
facts had been known at an early period, the celebrated
theory of the enclosure of germs, so warmly advocated
by Bonnet, would have preserved still longer its intrepid
defenders.

With but few exceptions, all the Hemiptera are para-
sites of the vegetable kingdom. There are only very few
which attack animals. There is one species, the name
of which may be readily guessed (Acanthia lectularia),
which pursues us relentlessly everywhere, for it will
wait for months and years, always equally greedy of
our blood. It surprises us during the night, and does
not wait till its digestion is complete before it attacks
us again. Happily for us, another hemipterous insect,
the masked reduvius (Reduvius personatus) penetrates like

268 ANIMAL PARASITES AND MESSMATES.

the preceding one into our apartments, and covers itself
with dust, in order the more readily to fall upon its
enemy; but man is not sufficiently acquainted with
its habits, to make war in common with it on this
miserable parasite. We ought for this purpose to place
the masked reduvius under the protection of the law,
to collect the various kinds together, and to offer pre-
miums for the most vigorous races.

INDEX.

1

Acantata lectularia, 267
Acaridz, 130
of reptiles, 135
insects, 135
——— molluses, 136
Acarus, itch, 131
eruditus, 137
marginatus, 134
Actinia carcinopodus, 63
Adamsia, 26
Agamonema, 234
Alardus caudatus, 45
Albertia, 35, 78
Alciopina, 47
Alcyonium domuncula, 27
Alepas on Spinax niger, 58
Allotria victrix, 172
Amphinoma, 43
Amphistomum sub-clavatum, 203
Ampularia and Spherium, 40
Ancei, 72
Anelasma squalicola, 58
Anemone of Chinese sea, 7
——— and Pyades, 26
Angler (fishing frog), 33
Anguillula macroura, 248
scandens, 181
Anguillulina, 182
Anilocra, 29
Anodonts, young, 39
Anoplodium parasita, 46
Apterychtus ocellatus
Arcturus Baffini, 41
Argas chinche, 133
Persian, 133
—— reflexus, 143
—— Americanus, 134

Arguli, 34, 72

Arius bookei, 8
Ascaracantha tenuis, 250
Ascaris acus, 241

inflexa, 237
lumbricoides, 95
—— megalocephala, 241
——— nigro-venosa, 157
vesicularis, 237
Ascaroides limacis, 83
Asellug medus» (Dalyell), 21
Asilus crabroniformis, 121
Astacobdella, 81
Asteracheres Lilljeborgii, 152
Asteromorpha levis, 48
Atax, 136

Axinella, 66

BaLanriwz on Matamata, 58
Balatro calvus, 35,
Baudroie (angler), 33
Bdellura, 46

Bernard the Hermit, 23
Berne, 120

Bilharzia, 105

Birgus, 25

Black-flies, 116

Bonellia (male), 139
Bopyrus, 32, 144
Bothriocephalus latus, 105
Brachycera, 115

Bracon iniator, 168
Branchellions, 113
Bryozoa, 41

Bugs, 124

—— of Miona, 133

270

Cautra lerneodiscus, 146

Caligi, 34, 44

with cable, 72

Caligulus elegans, 73

Callianassa, 28

Cancer lanosus, 22

Cancrisocia expansa, 22

Caprella, 77

Caris elliptica, 135

Cecidomya, 171

Cellepora, 62

Cenobita, 25

Cepes distortus, 145

Ceratopogon, 119

Cercariz, 192

Cestodes, 204

Chetogaster, 114

Chetopterus insignis, 43

Chalcidide, 166

Chama squamata, 19

Pliny on the, 18

Chelonobia, 58

Cheyletus of Leroy, 137

Chigoé, 105, 141

Chironomus, 116

Chrysaora isocela, 10

Cimex lectularia, 123

Cirrhipedes, 56

on Neptunus, 59

——on the Langouste of
Cape Verd, 58

Clione, 50

Cochlialepsis parasitus, 39

Coenurus of the Sheep, 99

Comatula, 36

Conchoderma gracile, 151

on Sea Snakes, 58

Conchodytes, 17

Concholepas Peruviana, 60

Conops, 176

Corethria on Sertularia abietina, 66

Corethra, 116

Coronilla robusta, 248

Coronula, 56 :

Crenella on Sponge, 40, 61

Creusia, 60

Crisix, 61

Cryptolepas, 57

Cryptolithoides typicus, 22

Cryptophiolus minutus on Concho-
lepas, 60

INDEX.

Culex pipiens, 116, 118

Cucullanus elegans, 238

Cucumerina, 71

Cuterebra noxialis, 175

Cyami, 34, 76

Cyanea arctica, 49

Cydippe densa, 47

Cylicobdella lumbricoides, 112

Cymothoa, 9

Cymothoe, 31

-——— of Trachina vipera, 32
fresh-water, 32 =
stromatei, 31

Cynips of Aphis, 172

Cypreea on Melithexa, 38

Cysticercus tenuicollis, 222

—— of the pig, 215

rabbit, 220

DemoveEx caninus, 134
Demodicidew, 134
Dactylometra quinquecirra, 9
Dermanyssus avium, 135
Diadema, 56, 60

Dichelaspis on Sea Snakes, 58
Dicyema, 161

Diplozoon, 98

Diporpa, 260

Distomum filicolle, 201
——— Goliath, 199
Distome with cables, 84
Distomes of Cheiroptera, 199
Distomids, 190

Distomum hepaticum, 95
ocreatum, 45
ventricosum, 45
Dochmius trigonocephalus, 238
Donzellina, 4

Drilus, 13.

Dromia, 22

Tcurnococcvs, 225

Echinomya, 176

Echinorhynchi, 251
Echinorhynchus angustatus, 252
gigas, 96

— heruca, 251

Elminius, 60
Enaleyonium rubricundum, 152
Enchelyophis vermicularis, 6
Enterocola fulgens, 151

INDEX.

Entoconcha, 37, 158
Entoniscus porcellane, 146
Epichtys, 31
Epibdella, 259
Epizoanthus Americanus on Eu-
pagurus, 63
Eubranchella, 112
Eulime, 36
Euplectella, 23, 30, 50
Kuriechinus imbecillus, 20
Eurysilenium, 152

Fasra Chilensis, 20
Fierasfer,5 =.

Filaria of Medina, 105, 153
immitis, 153

attenuata, 234
Filaroides mustelarum, 250
Fishing Frog and Amphipod, 33
Fleas, 126

— harnessed, 129

of the sea shore, 128
Dugés on, 128

———- Van Helmont on, 127
Flies, 119

Ganr.y, 112 ;
Galathea spinirostris on Coma-
tula, 20, 61
Gammarus of Avicula, 33
Gebia, 28
Gerardia Lamarckii, 49
Glossina morsitans, 119
Gnats, 116
Gordius, 153
bifurcus, 180
Indian, 180
ornatus, 153
Gregarins, 160
Guinea worm, 105, 158
Gyges branchialis, 145
Gyrodactyli, 261
Gyrodactylus elegans, 262
Gyropeltis, 74

HaticHonpria suberea, 63
Halodactylus, 62
Hematopinus tenuirostris, 129
Helmidasys, 47

Hoemieuryale, 49
Hemioniscus, 60

\

271

Hemiptera, 262
Hemistomum alatum, 204
Heterodera Schachtii, 248
Heteroneide, 236
Heterosammia, 63
Heteroura androphora, 248
Hippoboscus, 175:
Hirudinex, 108

of fishes, 109
—————— reptiles, 112
Histriobdella, 80

Holtenia Carpenteri, 50
Hopalocarcinus, 21
Hyalonema, 64

Hydrachna geographica, 136
Hydractiniz, 27

Hyperineg, 32

Hyperia Latreillii, 33
galba, 33

Icunevmons, 163

Ichthoxenus Jellingshausii, 31, 146
Jones, thoracicus, 145

Isopods, parasite, 143

Ixodes bovis, 184

of the dog, 135

reduvius, 134

ricinus, 96, 142

Kaxerior, 23
Kratzmilben, 133

Lavra, 152

Lemippa rubra, 152
Leeches, aquatic, 110
—— land, 111
Lepidonotus cirratus, 44
Leposphilus, 147

-Leptus autumnalis, 137
- Leptodera, 154

appendiculata, 248
———— pellio, 248
Lernea branchialis, 151
Lerneans, 148
Lerneoniscus, 146
—_—_———— nodicornis, 150
Lichnophora, 159
Lice of Bees, 171
Limosina, 136
Linguatula serrata, 231
Linguatulide, 134

272

Liothe pallidum, 71
Lithoscaspus, 21
Lipoptena of the Stag, 177
Loxostoma, 41

Lucilia hominivora, 120
Liriope, 28

Lysidice erythrocephala, 43

Macaco Worm, 175
Magilus, 39

Maia and Polypidom, 20
Malacobdella, 109
Maringouins, 116

Measled pork, 190

Meloé 173

Meloidez, 171

Melophagus of the Sheep, 177
Membranipora, 41

Mermis, 158

Messmates fixed, 53
————— free, 4
Midges, 116 ©
Mnemiopsis, 44

Mnestra parasites, 62
Modiola, 16

Modiolaria, 40
Monostomata, 2013
Monostoma mutabile, 20%
bijugum, 201
verrucosum, 191
Mosquitoes, 117

Musca hominivora, 119
Mutualists, 68

Myasis, 123

Myzobdella, 8
Myzostoma, 42

Nais, 114

Nebalia, 35

Nemertes carcinophilus, 46
Nemocera, 115

Nereis succinea, 42
tethycola, 45
Nirmus buteonivorus, 70
Nitzchia elegans, 259
Notonecta, 124
Notopterophorus, 151
Nycteribia, 123

OcrosoTHRiuM merlangi, 261
Octocotyle lanceolata, 261

INDEX.

Odontobius, 45

Giga on Hyalonema, 30
Gstri, 172

Ollulanus tricuspis, 247, 250

- Onchocotyle appendiculata, 261

Opalina, 79
Ophiocnemis obseura, 48
Ophioneurus, 169
Ophiothela, 48
Ornithomya, 121
Ostracion, 10
Ostracotheres tridacnex, 17
Oxybeles lumbricoides, 7
Oxyuris brachyura, 248
—incurvata, 237
vermicularis, 241

Pacuycerca, 194

Paguri, 25 :

Pagurus Prideauxii, 26

Pandarus, 35

Parasites which undergo trans-
rt and metamorphosis,
183° ‘

——— free in their youth, 138

during their old age,

162

———- without transmigration,

255
Pedicellina, 41, 42
Pediculinz, 70
Peltogaster, 28, 60
Penella, 150
Pentastoma, 231
Philomedusa Vogtii
campa, 61
Phoxichilidium, 35
Phthiriasis, 125
Phthirius pubis, 126
Phronima, 25
Phryxus paguri, 27, 145
—— Rathkei, 145
Phylliroé bucephala, 61
Phylobothrium of the Dolphin, 207
Phylloxera vastatrix, 166
Physalia, 9
Picnogonon, 34
Pilot, 10
Pinnotheres, 18
Pisa Styx, 20, 61
Piscicola, 113

on Hale»

Planaria, 46

Platygaster cya:nus, 171
Platystoma, 7

Plover, Egyptian, Introd. xvi., 107
Polia involuta, 46
Polynema, 169

Polynoé, 43

Polyp of the Sterlet, 82
Polystomum integerrimum, 261
—— ocellatum, 261
Polythoa, 64

———— of the Adriatic, 63
Pontobdelle, 80, 111
Pontonia, 18

Porcellanz, 21

Porites, 62

Praniza, 75

Premnas biaculeatus, 7
Prosthetes cannelatus, 27
Protolepas, 60
Psorospermi#, 161
Pteroptus, 123

Pulex penetrans, 141
irritans, 128
Pylidium, 45

Pyrgoma, 60

Repvvivs personatus, 267
Remora, 11

Rhabdites, 156

Rhagio, 119

Rhipiptera, 257

Rhincoprion penetrans, 141
Ricini, 69, 72

Rictularia plagiostoma, 251
Rouget (Cheyletus eruditus), 137

SaBELLIPHiLus, 152
Sacculina, 59

Saphirina, 77

Sarcoptes mutans, 135
———— scabiei, 131
Scalpellum, 56, 60
Sclerostomum equinum, 238
——__——_—- pinguicola, 238
Scolyti, 168

Seison nebalix, 36
Simonea folliculi, 89, 134
Simulium molestum, 119
Siponculus concharum, 47
Sertularia parasitica, 63

INDEX. 273

Scrupocellarie, 61

Sitaris, 172

Smut in Corn, 181

Snail and Drilus, 13
Spiroptera obtusa, 246
Sphex, 170

Spherosoma of Leydig, 74
Spheronella Leuckarti, 151
Spherulariz, 235
Sphyriones, 151

Sphynx of Tithymalis, 166
Spirorbis, 44 ,
Staurosoma on Sabella, 35
Stegophilus insidiatus, 8, 9
Sterlet, 82

Stephanurus dentatus, 238
Stratiome chameleon, 177
Strebla vespertilionis, 175
Strepsiptera, 256

Stronguli, 238

——— of Porpoise, 239
Strongulus trigonocephalus, 240
—————- armatus, 93
commutatus, 239
filaria, 237
gigas, 239

K

Stylifer, 36
Stylops, 256

Stylorhynchus oligacanthus, 161
Sylon hippolytes, 60

Pandali, 60

Syngamus trachealis, 91
Syrphus, 122

Tapanvs bovinus, 120
Tachinaria, 166

Teenia coenurus, 222
cucumerina, 71
echinococcus, 225
lata, 226

magna, or Rhinoceros, 229
gigantea, 229 |
medio-canellata, 105
nana, 105

serrata, 71

solium, 97, 105
tenuicollis, 222
Temnophila, 47

Termes lucifuga, 236
Tetrarhynchus, 101

Ticks, 142

274

Ticks, African, 143
Trematoda, digenetic, 191
Trichinzg, 243

Trichiniasis, 242
Trichocera, 116
Trichocephalus affinis, 242
Trichodectes of the Dog, 70
Trichosomum crassicauda, 235, 250
Tridacna, 17

Tristoma, 259

Trombidium, 137
Tsetse,°119

Tubicinella, 34, 56
Tubularia, 84

Turtle Crab, Brown’s, 23

INDEX.

UpongEa, 44

VaGInicoua, 84
Vampires, 107
Vibrio anguillula, 249

Wasps, 170
Whales of southern hemisphere, 57

XENOBALANUS globicipitis, 57

ZANZARE, 116
Zeuxo, 146
Awischenwirth, 184

Opinions of the Press on the “‘ International Scientific Series.”

~

Tyndall’s Forms of Water.

rvol.,12mo. Cloth. Illustrated. . . . . . . « Price, $1.50.

«In the volume now published, Professor Tyndall has presented a noble illustration
of the acuteness and subtlety of his intellectual powers, the scope and insight of his
scientific vision, his singular command of the appropriate language of exposition, and
the peculiar vivacity and grace with which he unfolds the results of intricate scientific
research,’—M. Y. Tribune.

“The ‘Forms of Water,’ by Professor Tyndall, is an interesting and instructive
little volume, admirably printed and illustrated. Prepared expressly for this series, it
is in some measure a guarantee of the excellence of the volumes that will follow, and an
indication that the publishers will spare no pains to include in the series the freshest in-
vestigations of the best scientific minds.” —Boston F¥ournal,

‘*This series is admirably commenced by this little volume from the pen of Prof.
Tyndall. A perfect master of his subject, he presents in a style easy and attractive his
methods of investigation, and the results obtained, and gives to the reader a clear con-
ception of all the wondrous transformations to which water is subjected.” —Churchman.

II

Bagehot’s Physics and Politics.

I vol., 12mo. Price, $1.50.

“Tf the ‘International Scientific Series’ proceeds as it has begun, it will more than
fulfil the promise given to the reading public in its prospectus. The first volume, by
Frofessor Tyndall, was a model of lucid and attractive scientific exposition; and now
we have a second, by Mr. Walter Bagehot, which is not only very lucid and charming,
but also original and suggestive in the highest degree. Nowhere since the publication
of Sir Henry Maine’s ‘Ancient Law,’ have we seen so many fruitful thoughts sug-
gested in the course of a couple of hundred pages. . . . Todo justice to Mr. Bage-
hot’s fertile book, would require along article. With the best of intentions, we are
conscious of having given but a sorry account of it ia these brief paragraphs. But we
hope we have said enough to commend it to the attention of the thoughtful reader.”—
Prof. Joun Fiske, in the Atlantic Monthly.

‘“‘Mr. Bagehot’s style is clear and vigorous. We refrain from giving a fuller ac-
count of these suggestive essays, only because we are sure that our readers will find it
worth their while to peruse the book for themselves; and we sincerely hope that the
forthcoming parts of the ‘International Scientific Series’ will be as interesting.”—
Atheneum.

“Mr. Bagehot discusses an immense variety of topics connected with the progress
of societies and nations, and the development of their distinctive peculiarities; and his
book shows an abundance of ingenious and original thought."—ALFRED RussELt
Wa tace, in Nature.

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y-

Opinions of the Press on the “ International Scientific Series.”

IIL.
Foods.

By Dr. EDWARD SMITH.
1vol.,1zmo. Cloth. Illustrated. . . . . . . « Price, $1.75.

In making up THE INTERNATIONAL SciENTIFIC SERiES, Dr. Edward Smith was se-
lected as the ablest man in England to treat the important subject of Foods. His services
were secured for the undertaking, and the little treatise he has produced shows that the
choice of a writer on this subject was most fortunate, as the book is unquestionably the
clearest and best-digested compend of the Science of Foods that has appeared in our
language.

“The book contains a series of diagrams, displaying the effects of sleep and meals
on pulsation and respiration, and of various kinds of food on respiration, which, as the
results of Dr. Smith’s own experiments, possess a very high value. We have not far
to go in.this work for occasions of favorable criticism; they occur throughout, but are

perhaps most apparent in those parts of the subject with which Dr. Smith’s name is es-
pecially linked.”—London Examiner.

** The union of scientific and popular treatment in the composition of this work will
afford an attraction to many readers who would have been indifferent to purely theoreti-
cal details. . . . Still his work abounds in information, much of which is of great value,
and a part of which could not easily be obtained from other sources. Its interest is de-
cidedly enhanced for students who demand both clearness and exactness of statement,
by the profusion of well-executed woodcuts, diagrams, and tables, which accompany the
volume. , . . The suggestions of the author on the use of tea and coffee, and of the va-
rious forms of alcohol, although perhaps-not strictly of a novel character, are highly in-
structive, and form an interesting portion of the volume.”—WV. Y. Tribune.

IV. 7
Body and Mind.
THE THEORIES OF THEIR RELATION.
By ALEXANDER BAIN, LL. D.
ryol., 12mo. Cloth... . . + + + « + ~ Price, $1.50.

Proressor Bain is the author of two well-known standard works upon the Science
ef Mind—‘‘ The Senses and the Intellect,” and ‘‘ The Emotions and the Will.” He is
one of the highest living authorities in the school which holds that there can be no sound
or valid psychology unless the mind and the body are studied, as they exist, together.
_ It contains a forcible statement of the connection between mind and body, study-
ing their subtile interworkings by the light of the most recent physiological investiga-
tions. The summary in Chapter V., of the investigations of Dr. Lionel Beale of the
embodiment of the intellectual functions in the cerebral system, will be found the
freshest and most interesting part of his book. Prof. Bain’s own theory of the connec-
tion between the mental and the bodily part in man is stated by himself to be as follows:
There is ‘one substance, with two sets of properties, two sides, the physical and the
mental—a doublefaced unity.’ While, in the strongest manner, asserting the union
of mind with brain, he yet denies ‘the association of union 2% A/ace,’ but asserts the
union of close succession in time,’ holding that ‘the same being is, by alternate fits, un-
der extended and under unextended consciousness.” ’—Christian Register.

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y.

Opinions of the Press on the “ International Scientific Series.»

The Study of Sociology.

By HERBERT SPENCER.
1vol.,rzmo. Cloth . ...... =... . . Price, $1.50.

«The philosopher whose distinguished name gives weight and influence to this vol-
ume, has given in its pages some of the finest specimens of reasoning in all its forms
and departments. There is a fascination in his array of facts, incidents, and opinions,
which draws on the reader to ascertain his lusi The 1 and cal o!
his treatment of acknowledged difficulties and grave objections to his theories win for
him a close attention and sustained effort, on the part of the reader, to comprehend, fol-
low, grasp, and appropriate his principles. This book, independently of its bearing
upon sociology, is valuable as lucidly showing what those essential characteristics are
which entitle any arrangement and connection of facts and deductions to be called a
science.” —Episcopalian,

‘This work compels admiration by the evidence which it gives of immense re-
search, study, and observation, and is, withal, written in a popular and very pleasing
style. It is a fascinating work, as well as one of deep practical thought.”’—Bost, Post.

“Herbert Spencer is unquestionably the foremost living thinker in the psychological
and sociological fields, and this volume is an important contribution to the science of
which it treats, . . . It will prove more popular than any of its author’s other creations,
for it is more plainly addressed to the people and has a more practical and less specu-
lative cast. It will require thought, but it is well worth thinking about.”—A /bany
Evening Fournal, :

The N ee Cheney:

By JOSIAH P. COOKE, Jr.,
Erving Professor of Chemistry and Mineralogy in Harvard University.
I vol, tzmo. Cloth . . ... . . +... . Price, $2.00.

“The book of Prof. Cooke is a model df the modern popular science work. It has
just the due proportion of fact, philosophy, and true romance, to make it a fascinating
companion, either for the voyage or the study.” —Darly Graphic.

“This admirable monograph, by the distinguished Erving Professor of Chemistry
in Harvard University, is the first American contribution to ‘The International Scien-
tific Series,’ and a more attractive piece of work in the way of popular exposition upon
a difficult subject has not appeared in a long time. It not only well sustains the char-
acter of the volumes with which it is iated, but its reproduction in European coun-
tries will be an honor to American science.”—New York Tribune.

‘* All the chemists in the country will enjoy its perusal, and many will seize upon it
as a thinglonged for. For, to those advanced students who have kept well abreast of
the chemical tide, it offers a calm philosophy. To those others, youngest of the class,
who have emerged from the schools since new methods have prevailed, it presents a
generalization, drawing to its use all the data, the relations of which the newly-fledged
fact-seeker may but dimly perceive without its aid... . To the old chemists, Prof.
Cooke’s,treatise is like a message from beyond the mountain, They have heard
changes in the science; the clash of the battle of old and new theories has stirred them
from afar. The tidings, too, had come that the old had given way; and little more than
this they knew. . . . Prof. Cooke’s ‘ New Chemistry’ must do wide service in bringing
to close sight the little known and the longed for. . . .. As a philosophy it is elemen-
tary, but, as a book of science, ordinary readers will find it sufficiently advanced.’
Utica Morning Herald,

D. APPLETON & CO., Publishers, 549 & 551 Broadway, N. Y

Opinions of the Press on the “International Scientific Series.”

VIL

The Conservation of Energy..
By BALFOUR STEWART, LL. D., F. R.5.
With an Appendix treating of the Vital and Mental Applications of the Doctrine,
1vol., r2mo. Cloth. Price, $1.50.

“ The author has succeeded in presenting the facts in a clear and satisfactory manner,
using simple language and copious illustration in the presentation of facts and prin-
ciples, confining fimeelf however, to the physical aspect of the subjegt. In the Ap-
pendix the operation of the principles in the spheres of life and mind is supplied by
the essays of Professors Le Conte and Bain.”—Okio Farmer.

« Prof. Stewart is one of the best known teachers in Owens College in Manchester.

“The volume of THe INTERNATIONAL SCIENTIFIC SERIES now before us is an ex-
cellent illustration of the true method of teaching, and will well compare with Prof.
Tyndall’s charming little book in the same series on ‘ Forms of Water,” with illustra-
tions enough to make clear, but not to conceal his thoughts, in a style simple and
brief.” —Christian Register, Boston.

“The writer has wonderful ability to compress much information into a few words.
It is a rich treat to read such a book as this, when there is so much beauty and force
combined with such simplicity. —Zastern Press.

VL

Animal Locomotion;
Or, WALKING, SWIMMING, AND FLYING.

With a Dissertation on Aévonautics.

By J. BELL PETTIGREW, M.D., F.R.S., F.R.S.E.,
F.R.C. P.E.

Ivol.,%2mo, . . . . « Price, $1.78.

“This work is more than a contribution to the stock of entertaining knowledge,
though, if it only pleased, that would be sufficient excuse for its publication. But Dr.
Pettigrew has given his time to these investigations with the ultimate purpose of solv-
ing the difficult problem of Aéronautics. To this he devotes the last fifty pages of his
book. Dr. Pettigrew is confident that man will yet conquer the domain of the air.”—
N.Y. Fournal of Commerce.

, ‘Most persons claim to know how to walk, but few could explain the mechanical
principles involved in this most ordinary transaction, and will be surprised that the
movements of bipeds and quadrupeds, the darting and rushing motion of fish} and the
erratic flight of the denizens of the air, are not only anologous, but can be reduced to
similar formula. The work is profusely illustrated, and, without reference to the theory
it is designed to expound, will be regarded as a valuable addition to natural history.”
—Omaha Republic.

D. APPLETON & CO., PUBLISHERS, 549 & 551 Broadway, N. Y.

Opinions of the Press on the “International Scientific Series.”

Responsibility in Mental Disease.

By HENRY MAUDSLEY, M.D.,

Fellow of the Royal College of Physicians; Professor of Medical Jurisprudence
in University College, London.

1 vol., 12mo. Cloth. . . Price, $1.50.

“Having lectured in a medical college on Mental Disease, this book has been a
feast to us. It handles a Fess subject in a masterly manner, and, in our judgment, the
positions taken by the author are correct and well sustained.”—Fastor and People.

“ The author is at home in his subject, and presents his views in an almost singu-
larly clear and satisfactory manner. . , . The volume is a valuable contribution to one
of the most difficult, and at the same time one of the most important subjects of inves-
tigation at the present day."—W. VY. Observer.

“Tt is a work profound and searching, and abounds in wisdom.” —Fittsburg Com-
mercial,

_ “Handles the important topic with masterly power, and its suggestions are prac-
tical and of great value.” —Providence Press.

The SGence of Law.

By SHELDON AMOS, M.A.,

Profe of Jurisprud in University College, London; author of ‘‘ A Systematic
View of the Science of Jurisprudence,” ‘‘ An English Code, its Difficulties
and the Modes of overcoming them,” etc., etc.

1 vol, rz2mo. Cloth, . . . . Price, $1.75.

“The valuable series-of ‘International Scientific’ works, prepared by eminent spe-
cialists, with the intention of popularizing information in their several branches of
knowledge, has received a good accession in this compact and thoughtful volume, It
is a difficult task to give the outlines of a complete theory of law in a portable volume,
which he who runs may read, and probably Professor Amos himself would be the last
to claim that he has perfectly succeeded in doing this. But he has certainly done much
to clear the science of law from the technical obscurities which darken it to minds which
have had no legal training, and to make clear to his ‘lay’ readers in how true and higha
sense it can assert its right to be considered a science, and not a mere practice.” —The
Christian Register.

“The works of Bentham and Austin are abstruse and philosophical, and Maine’s
require hard study and a certain amount of special training. The writers also pursue
diferent lines of investigation, and can only be garded as prehensive in the de-
partments they confined themselves to. It was left to Amos to gather up the result
and present the sci in its full The unquestionable merits of this, his last book,
are, that it contains a complete treatment of a subject which has hitherto heen handled
by specialists, and it opens up that subject to every inquiring mind. . . . To do justice
to ‘ The Science of Law’ would require a longer review than we have space for. We
have read no more interesting and instructive book for some time. Its themes concern
every one who renders obedience to laws, and who would have those laws the best

ossible. The tide of legal reform which set in fifty years ago has to sweep yet higher
if the flaws in our jurisprudence are to be removed. ‘The process of change cannot be
better guided than by a well-informed public mind, and Prof. Amos has done great
service in materially helping to promote this end.” —Buffalo Courier.

D. APPLETON & CO., PusBLisHERs, 549 & 551 Broadway, N. Y-

Opinions of the Press on the “‘ International Scientific Series.”

XI,

Animal Mechanism,

A Treatise on Terrestrial and Aérial Locomotion.
By E. J. MAREY,
Professor at the College of France, and Member of the Academy of Medicine.
With x17 Illustrations, drawn and engraved under the direction of the author.
rvol.,z2mo. Cloth . . . Price, $1.75
“We hope that, in the short glance which we have taken of some of the most im-

portant points discussed in the work before us, we have succeeded in interesting our
readers sufficiently in its contents to make them ‘curious to learn more of its subject-
matter. We cordially recommend it to their attention.

“The author of the present work, it is well known, stands at the head of those
physiologists who have investigated the mechanism of animal dynamics—indeed, we
may almost say that he has made the subject his own. By the originality of his con-
ceptions, the ingenuity of his constructions, the skill of his analysis, and the persever-
ance of his investigations, he has surpassed all others in the power of unveiling the
complex and intricate movements of animated beings.” —Popular Sczence Monthly.

. XII.

History of the Conflict between

Religion and Science.

By JOHN WILLIAM DRAPER, M. D., LL. D.,
Author of The Intellectual Development of Europe.”
1 vol., 12mo. A A , . . . : < Price, $1.75.

«This little ‘ History’ would have been a valuable contribution to literature at any
aime, and is, in fact, an admirable text-book upon a subject that is at present engross-
ing the attention of a large number of the most serious-minded people, and it is no
small compliment to the sagacity of its distinguished author that he has so well gauged
the requirements of the times, and so adequately met them by the preparation of this
volume. It remains to be added that, while the writer has flinched from no responsi-
bility in his statements, and has written with entire fidelity to the demands of truth
and justice, there is not a word+in his book that can give offense to candid and fair-
minded readers.”—W. V. Evening Post.

“‘ The key-note to this ‘volume is found in the antagonism between the progressive
tendencies of the human mind and the pr ions of ecclesiastical authority, as devel-
oped in the history of modern science. No previous writer has treated the subject
from this point of view, and the present monograph will be found to possess no less
originality of conception than vigor of reasoning and wealth of erudition. .. . The
method of Dr. Draper, in his treatment of the various questions that come up for dis-
cussion, is marked by singular impartiality as well as consummate ability. Through-
out his work he maintains the position of an historian, not of an advocate. His tone is
tranquil and serene, as becomes the search after truth, with no trace of the impassioned
ardor of controversy. He endeavors so far to identify himself with the contending
parties as to gain a clear comprehension of their motives, but, at the'same time, he
submits their actions to the tests of a cool and impartial examination.”—WV. V. Tribune.

D. APPLETON & CO., PUBLISHERS, 549 & 551 Broadway, N. Y.

ul
Opinions of the Press on the “International Scientific Series.”

XIII.
THE DOCTRINE OF

Descent, and Darwinism.
By OSCAR SCHMIDT,

Professor in the University of Strasburg.
WitH 26 Wooncuts.
1 vol, 12mo. Cloth . . . . . . . . Price, $1.50.

“The entire subject is di d with a fresh as well as an elaboration of de-
tail, that renders his work interesting in a more than usual degree. The facts upon
which the Darwinian theory is based are presented in an effective manner, conclusions
are ably defended, and the question is treated in more compact and available style
than in any other work on the same topic that has yet appeared. It is a valuable ad-
dition to the ‘ International Scientific Series, ”_ Boston Post.

“« The present volume is the thirteenth of the ‘International Scientific Series,’ and
is one of the most interesting of all of them. The subject-matter is handled with a
great deal of skill and earnestness, and the courage of the author in avowing his opin-
tons is much to his credit. . . . This volume certainly merits a careful perusal,”—
Hartford Evening Post.

“The volume which Prof. Schmidt has devoted to this theme is a valuable contri-
bution to the Darwinian literature. Philosophical in method, and eminently candid,
it shows not only the ground which Darwin had in his researches made, and conclu-
sions reached before him to plant his theory upon, but shows, also, what that theory
really is, a point upon which many good people who talk very earnestly about the
matter are very imperfectly informed.” —Detrott Free Press.

XIV.

The Chemistry of Light and
Photography ;
In its Application to Art, Science, and Industry.

By Dr. HERMANN VOGEL,
Professor in the Royal Industrial Academy of Berlin.

WitH 100 ILLUSTRATIONS.
f2m0. s 6 6% & * + % © & G x « Price, $2.00;

‘‘Out of Photography has sprung a new science—the Chemistry of Light—and, in.
giving a popular view to the one, Dr. Vogel has presented an analysis of the principles
and processes of the other. His treatise is as entertaining as it 1s instructive, pleas-
antly combining a history of the progress and practice of photography—from the first
rough experiments of Wedgwood and Davy with sensitized paper, in 1802, down to
the latest improvements of the art—with technical illustrations of the scientific theories
on which the art is based. It is the first pt in any 1 of photography to set
forth adequately the just claims of the invention, both from an artistic and a scientific
point of view, and it must be conceded that the effort has been ably conducted.”—
Chicago Tribune.

_D, APPLETON & CO., PUBLISHERS, 549 & 551 Broadway, N. Y.

Opinions of the Press on the “International Scientific Series.”

XV.
Fungi;
THEIR NATURE, INFLUENCE, AND USES.
By M. C. COOKE, M.A., LL.D.
Edited by Rev. M. J. BERKELEY, M.A., F.L.S.
With 109 Illustrations. Price, $1.50.

*«Bven if the name of the author of this work were not deservedly eminent, that of
the editor, who has long stood at the head of the British fungologists, would be a suf-
ficient voucher for the accuracy of one of the best botanical monographs ever issued
from the press. . . . The structure, germination, and growth of all these widely-dif-
fused organisms, their habitats and influences for good and evil, are systematically
described.”—Wew York World.

“Dr. Cooke’s book contains an admirable vészmdé of what is known on the struct-
ure, growth, and reproduction of fungi, together with ample bibliographical references
to original sources of information.”’—Lozdon Atheneum. 2

“The production of a work like the one now under review represents a large
amount of laborious, difficult, and critical work, and one in which a serious slip or fatal
error would be one of the easiest matters possible, but, as far as we are able to judge,
the new hand-book seems in every way well suited to the requirements of all beginners
in =a difficult and involved study of fungology.”—T7ke Gardener's Chronicle (I.on-
don),

The Life and Growth of Language:

AN OUTLINE OF LINGUISTIC SCIENCE.

By WILLIAM DWIGHT WHITNEY,
Professor of Sanskrit and Comparative Philology in Yale College.
Ivol., 12mo. Cloth. Price, $1.50.

«Prof. Whitney is to be commended for giving to the public the results of his ripe
scholarship and unusually profound researches in simple language. He draws illus-

ions an les of the principles which he wishes to impast, from common life
and the words in frequent use,

“‘The topics discussed in this volume are, for the most part, those which have
been already treated by other writers on philology, and even by the author himself, in
his volume on ‘ Language, and the Study of Language,’ published a few years ago, .
and, though many of the truths here set forth are those with which students in the
same line of investigation are generally familiar, all will rejoice to see them restated in
such a fresh and simple way.

** This work, while valuable to scholars, will be interesting to every one.” —T7he
Churchman. | :

. This work is an important contribution to a science which has advanced steadily
under conditions that appear constantly to throw an increasing light on difficult ques.
tions, and at each step clear the way for further discoveries.” —Chicago Inter-Ocean.

“Prof. Whitney is undoubtedly one of the foremost of Gnghdh speek oe, philologists,
and occupies an enviable position in the wider circle of European students of language.
__ ‘*His style, clear, simple, picturesque, abounding in striking illustrations, and apt
in comparisons, is admirably fitted to be the vehicle of a popular treatise like the work
under consideration.” —Portland Daily Press. ,

D. APPLETON & CO., PUBLISHERS, 549 & 551 Broadway, N. Y.

Opinions of the Press on the “ International Scientific Series.”

XVII.

Money and the Mechanism of Ex-

change.
By W. STANLEY FEVONS, M.A., F.R.S.,

Professor of Logic and Political Economy in the Owens College, Manchester.
I vol.,12mo. Cloth. Price, $1.75.

“ He offers us what a clear-sighted, cool-headed, scientific student has to say on the
nature, properties, and natural laws of money, without regard to local interests or na-
tional bias, His work is popularly written, and every page is replete with solid instruc-
tion of a kind that is just now lamentably needed by multitudes of our people who are
victimized by the grossest fallacies." —Popular Science Monthly.

“If Professor Jevons’s book is read as extensively as it deserves to be, we shall
have sounder views on the use and abuse of money, and more correct ideas on what a
circulating medium really means.” —Boston Saturday Evening Gazette.

“Professor Jevons writes in a sprightly but colorless style, without trace of either
.prejudice or mannerism, and shows no commitment to any theory. The time is not
very far distant, we hope, when legislators will cease attempting to legislate upon
money before they know what money is, and, as a possible help toward such a change,
Professor Jevons deserves the credit of having made a useful contribution to a depart-
ment of study long too much neglected, but of late years, we are gratified to say, be-
coming less so.""—The Financier, New York.

XVIII.

The Nature of Light,

WITH A GENERAL ACCOUNT OF PHYSICAL OPTICS.
By Dr. EUGENE LOMMEL
(University of Erlangen).
1 vol., 12mo. Cloth. ‘ é 2 Price, $2.00.

“In the present treatise, Professor Lommel has given an admirable outline of the
nature of light and the laws of optics.

“Unlike most other writers on this subject, the author has, we think, wisely post-
poned all reference to theories of the nature of light, until the laws of reflection, re-
fraction, and absorption, have been clearly set before the reader. Then, in the fifteenth

h , Profe L 1 di Fresnel’s famous interference experiment, and
leads the reader to see that the undulatory theory is the only conclusion that can be
satisfactorily arrived at, A clear exposition is now given of Huyghen’s theory, after
which follow several chapters on the diffraction and polarization of light-bearing waves.

‘« The reader is thus led onward much in the same way as the science itself has un-
folded, and this, we think, is the surest and best way of teaching natural knowledge.

** We have said enough to show that Professor Lommel’s treatise is a useful contri-
bution to the ‘International Series’—a book that can thoroughly be understood and
enjoyed by any intelligent reader who may not have had any special scientific train-
ing.” —Nature.

“In a style singularly lucid, considering the abstruse nature of the subject treated,
Dr. Lommel unfolds the learning of the scientists on the nature and phenomena of
light."—Philadelphia Inquirer.

“ As a popular introduction to physical optics, it would be difficult to find a more
satisfactory work than the one by Dr. Lommel, which has just appeared in the excel-
lent ‘ International Scientific Series.’”"—The English Mechanic.

D. APPLETON & CO., PUBLISHERS, 549 & 551 Broadway, N. Y.

THE INTERNATIONAL SCIENTIFIC SERIES.

D. AprLeton & Co. have the pleasure of announcing that they have made arrange.
ments for publishing, and have recently commenced the issue of, a SERIES OF Popu-
Lar Monocrapus, or small works, under the above title; which will embody the results
of zecent inquiry in the most interesting departments of advancing science.

The character and scope of this series will be best indicated by a reference to the
names and subjects included in the subjoined list, from which it will be seen that the
coéperation of the most distinguished professors in England, Germany, France, and the
United States, has been secured, and negotiations are pending for contributions from
other eminent scientific writers.

The works will be issued in New York, London, Paris, Leipsic, Milan, and St.
Petersburg.

The INTERNATIONAL SCIENTIFIC SERIES is entirely an American project, and was
originated and organized by Dr. E. L. Youmans, who has spent much time in Europe,
arranging with authors and publishers,

FORTHCOMING VOLUMES.
Prof. W. KINGDON CLIFFORD, M.A. The First Principles of the Exact
Sci ‘plained to the Non-mathematical
Prof. T. H. HUXLEY, LL. D., F.R.S. Bodily Motion and Consciousness.
Dr. W. B, CARPENTER, LL. D., F.R.S. The Physical Geography of the Sea.

Prof. WILLIAM ODLING, F.R.S. Tike Old Chemistry viewed from the New
Stand-point.

W. LAUDER LINDSAY, M.D., F.R. S.E. Mind in the Lower Animals.
Sir JOHN LUBBOCK, Bart, F.R.S. On Ants and Bees.

Prof. W. T. THISELTON DYER, B.A., B.Sc. Form and Habit in Flowering
Plants.

Mr. J. N. LOCKYER, F.R.S. Spectrum Analysis.
Prof. MICHAEL FOSTER, M.D. Protoplasm and the Cell Theory.
H. CHARLTON BASTIAN, M.D.,F.R.S. The Brain as an Organ of Mind.

Prof. A. C. RAMSAY, LL. D. »F.R.S. Zarth Sculpture: Hills, Valleys, Moun«

tains, Plains, Rivers, Diller » How they were Produced, and how they have
been Destroyed.

Prof. RUDOLPH VIRCHOW (Berlin University). Morbid Physiological Action,
Prof. CLAUDE BERNARD. History of the Theories of Life.

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