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Birds are furnished with a mouth, but with an exceptional one,
for they have neither lips nor teeth, but a beak. Neither have they
ears nor a nose, but only passages for the sensations connected with
these organs: that for the nostrils in the beak, and that for
hearing in the head. Like all other animals they all have two eyes,
and these are devoid of lashes. The heavy-bodied (or gallinaceous)
birds close the eye by means of the lower lid, and all birds blink
by means of a skin extending over the eye from the inner corner; the
owl and its congeners also close the eye by means of the upper lid.
The same phenomenon is observable in the animals that are protected by
horny scutes, as in the lizard and its congeners; for they all without
exception close the eye with the lower lid, but they do not blink like
birds. Further, birds have neither scutes nor hair, but feathers;
and the feathers are invariably furnished with quills. They have no
tail, but a rump with tail-feathers, short in such as are
long-legged and web-footed, large in others. These latter kinds of
birds fly with their feet tucked up close to the belly; but the
small rumped or short-tailed birds fly with their legs stretched out
at full length. All are furnished with a tongue, but the organ is
variable, being long in some birds and broad in others. Certain
species of birds above all other animals, and next after man,
possess the faculty of uttering articulate sounds; and this faculty is
chiefly developed in broad-tongued birds. No oviparous creature has an
epiglottis over the windpipe, but these animals so manage the
opening and shutting of the windpipe as not to allow any solid
substance to get down into the lung.

Some species of birds are furnished additionally with spurs,
but no bird with crooked talons is found so provided. The birds with
talons are among those that fly well, but those that have spurs are
among the heavy-bodied.

Again, some birds have a crest. As a general rule the crest sticks
up, and is composed of feathers only; but the crest of the barn-door
cock is exceptional in kind, for, whereas it is not just exactly
flesh, at the same time it is not easy to say what else it is.

13

Of water animals the genus of fishes constitutes a single group
apart from the rest, and including many diverse forms.

In the first place, the fish has a head, a back, a belly, in the
neighbourhood of which last are placed the stomach and viscera; and
behind it has a tail of continuous, undivided shape, but not, by the
way, in all cases alike. No fish has a neck, or any limb, or testicles
at all, within or without, or breasts. But, by the way this absence of
breasts may predicated of all non-viviparous animals; and in point
of fact viviparous animals are not in all cases provided with the
organ, excepting such as are directly viviparous without being first
oviparous. Thus the dolphin is directly viviparous, and accordingly we
find it furnished with two breasts, not situated high up, but in the
neighbourhood of the genitals. And this creature is not provided, like
quadrupeds, with visible teats, but has two vents, one on each
flank, from which the milk flows; and its young have to follow after
it to get suckled, and this phenomenon has been actually witnessed.

Fishes, then, as has been observed, have no breasts and no
passage for the genitals visible externally. But they have an
exceptional organ in the gills, whereby, after taking the water in the
mouth, they discharge it again; and in the fins, of which the
greater part have four, and the lanky ones two, as, for instance,
the eel, and these two situated near to the gills. In like manner
the grey mullet-as, for instance, the mullet found in the lake at
Siphae-have only two fins; and the same is the case with the fish
called Ribbon-fish. Some of the lanky fishes have no fins at all, such
as the muraena, nor gills articulated like those of other fish.

And of those fish that are provided with gills, some have
coverings for this organ, whereas all the selachians have the organ
unprotected by a cover. And those fishes that have coverings or
opercula for the gills have in all cases their gills placed
sideways; whereas, among selachians, the broad ones have the gills
down below on the belly, as the torpedo and the ray, while the lanky
ones have the organ placed sideways, as is the case in all the
dog-fish.

The fishing-frog has gills placed sideways, and covered not
with a spiny operculum, as in all but the selachian fishes, but with
one of skin.

Morever, with fishes furnished with gills, the gills in some
cases are simple in others duplicate; and the last gill in the
direction of the body is always simple. And, again, some fishes have
few gills, and others have a great number; but all alike have the same
number on both sides. Those that have the least number have one gill
on either side, and this one duplicate, like the boar-fish; others
have two on either side, one simple and the other duplicate, like
the conger and the scarus; others have four on either side, simple, as
the elops, the synagris, the muraena, and the eel; others have four,
all, with the exception of the hindmost one, in double rows, as the
wrasse, the perch, the sheat-fish, and the carp. The dog-fish have all
their gills double, five on a side; and the sword-fish has eight
double gills. So much for the number of gills as found in fishes.

Again, fishes differ from other animals in more ways than as
regards the gills. For they are not covered with hairs as are
viviparous land animals, nor, as is the case with certain oviparous
quadrupeds, with tessellated scutes, nor, like birds, with feathers;
but for the most part they are covered with scales. Some few are
rough-skinned, while the smooth-skinned are very few indeed. Of the
Selachia some are rough-skinned and some smooth-skinned; and among the
smooth-skinned fishes are included the conger, the eel, and the tunny.

All fishes are saw-toothed excepting the scarus; and the teeth in
all cases are sharp and set in many rows, and in some cases are placed
on the tongue. The tongue is hard and spiny, and so firmly attached
that fishes in many instances seem to be devoid of the organ
altogether. The mouth in some cases is wide-stretched, as it is with
some viviparous quadrupeds. . . .

With regard to organs of sense, all save eyes, fishes possess
none of them, neither the organs nor their passages, neither ears
nor nostrils; but all fishes are furnished with eyes, and the eyes
devoid of lids, though the eyes are not hard; with regard to the
organs connected with the other senses, hearing and smell, they are
devoid alike of the organs themselves and of passages indicative of
them.

Fishes without exception are supplied with blood. Some of them are
oviparous, and some viviparous; scaly fish are invariably oviparous,
but cartilaginous fishes are all viviparous, with the single exception
of the fishing-frog.

14

Of blooded animals there now remains the serpent genus. This genus
is common to both elements, for, while most species comprehended
therein are land animals, a small minority, to wit the aquatic
species, pass their lives in fresh water. There are also sea-serpents,
in shape to a great extent resembling their congeners of the land,
with this exception that the head in their case is somewhat like the
head of the conger; and there are several kinds of sea-serpent, and
the different kinds differ in colour; these animals are not found in
very deep water. Serpents, like fish, are devoid of feet.

There are also sea-scolopendras, resembling in shape their land
congeners, but somewhat less in regard to magnitude. These creatures
are found in the neighbourhood of rocks; as compared with their land
congeners they are redder in colour, are furnished with feet in
greater numbers and with legs of more delicate structure. And the same
remark applies to them as to the sea-serpents, that they are not found
in very deep water.

Of fishes whose habitat is in the vicinity of rocks there is a
tiny one, which some call the Echeneis, or 'ship-holder', and which is
by some people used as a charm to bring luck in affairs of law and
love. The creature is unfit for eating. Some people assert that it has
feet, but this is not the case: it appears, however, to be furnished
with feet from the fact that its fins resemble those organs.

So much, then, for the external parts of blooded animals, as
regards their numbers, their properties, and their relative
diversities.

15

As for the properties of the internal organs, these we must first
discuss in the case of the animals that are supplied with blood. For
the principal genera differ from the rest of animals, in that the
former are supplied with blood and the latter are not; and the
former include man, viviparous and oviparous quadrupeds, birds,
fishes, cetaceans, and all the others that come under no general
designation by reason of their not forming genera, but groups of which
simply the specific name is predicable, as when we say 'the
serpent,' the 'crocodile'.

All viviparous quadrupeds, then, are furnished with an oesophagus
and a windpipe, situated as in man; the same statement is applicable
to oviparous quadrupeds and to birds, only that the latter present
diversities in the shapes of these organs. As a general rule, all
animals that take up air and breathe it in and out are furnished
with a lung, a windpipe, and an oesophagus, with the windpipe and
oesophagus not admitting of diversity in situation but admitting of
diversity in properties, and with the lung admitting of diversity in
both these respects. Further, all blooded animals have a heart and a
diaphragm or midriff; but in small animals the existence of the latter
organ is not so obvious owing to its delicacy and minute size.

In regard to the heart there is an exceptional phenomenon
observable in oxen. In other words, there is one species of ox
where, though not in all cases, a bone is found inside the heart. And,
by the way, the horse's heart also has a bone inside it.

The genera referred to above are not in all cases furnished
with a lung: for instance, the fish is devoid of the organ, as is also
every animal furnished with gills. All blooded animals are furnished
with a liver. As a general rule blooded animals are furnished with a
spleen; but with the great majority of non-viviparous but oviparous
animals the spleen is so small as all but to escape observation; and
this is the case with almost all birds, as with the pigeon, the
kite, the falcon, the owl: in point of fact, the aegocephalus is
devoid of the organ altogether. With oviparous quadrupeds the case
is much the same as with the viviparous; that is to say, they also
have the spleen exceedingly minute, as the tortoise, the freshwater
tortoise, the toad, the lizard, the crocodile, and the frog.

Some animals have a gall-bladder close to the liver, and others
have not. Of viviparous quadrupeds the deer is without the organ, as
also the roe, the horse, the mule, the ass, the seal, and some kinds
of pigs. Of deer those that are called Achainae appear to have gall in
their tail, but what is so called does resemble gall in colour, though
it is not so completely fluid, and the organ internally resembles a
spleen.

However, without any exception, stags are found to have maggots
living inside the head, and the habitat of these creatures is in the
hollow underneath the root of the tongue and in the neighbourhood of
the vertebra to which the head is attached. These creatures are as
large as the largest grubs; they grow all together in a cluster, and
they are usually about twenty in number.

Deer then, as has been observed, are without a gall-bladder;
their gut, however, is so bitter that even hounds refuse to eat it
unless the animal is exceptionally fat. With the elephant also the
liver is unfurnished with a gall-bladder, but when the animal is cut
in the region where the organ is found in animals furnished with it,
there oozes out a fluid resembling gall, in greater or less
quantities. Of animals that take in sea-water and are furnished with a
lung, the dolphin is unprovided with a gall-bladder. Birds and
fishes all have the organ, as also oviparous quadrupeds, all to a
greater or a lesser extent. But of fishes some have the organ close to
the liver, as the dogfishes, the sheat-fish, the rhine or
angel-fish, the smooth skate, the torpedo, and, of the lanky fishes,
the eel, the pipe-fish, and the hammer-headed shark. The
callionymus, also, has the gall-bladder close to the liver, and in
no other fish does the organ attain so great a relative size. Other
fishes have the organ close to the gut, attached to the liver by
certain extremely fine ducts. The bonito has the gall-bladder
stretched alongside the gut and equalling it in length, and often a
double fold of it. others have the organ in the region of the gut;
in some cases far off, in others near; as the fishing-frog, the elops,
the synagris, the muraena, and the sword-fish. Often animals of the
same species show this diversity of position; as, for instance, some
congers are found with the organ attached close to the liver, and
others with it detached from and below it. The case is much the same
with birds: that is, some have the gall-bladder close to the
stomach, and others close to the gut, as the pigeon, the raven, the
quail, the swallow, and the sparrow; some have it near at once to
the liver and to the stomach as the aegocephalus; others have it
near at once to the liver and the gut, as the falcon and the kite.

16

Again, all viviparous quadrupeds are furnished with kidneys and
a bladder. Of the ovipara that are not quadrupedal there is no
instance known of an animal, whether fish or bird, provided with these
organs. Of the ovipara that are quadrupedal, the turtle alone is
provided with these organs of a magnitude to correspond with the other
organs of the animal. In the turtle the kidney resembles the same
organ in the ox; that is to say, it looks one single organ composed of
a number of small ones. (The bison also resembles the ox in all its
internal parts).

17

With all animals that are furnished with these parts, the parts
are similarly situated, and with the exception of man, the heart is in
the middle; in man, however, as has been observed, the heart is placed
a little to the left-hand side. In all animals the pointed end of
the heart turns frontwards; only in fish it would at first sight
seem otherwise, for the pointed end is turned not towards the
breast, but towards the head and the mouth. And (in fish) the apex
is attached to a tube just where the right and left gills meet
together. There are other ducts extending from the heart to each of
the gills, greater in the greater fish, lesser in the lesser; but in
the large fishes the duct at the pointed end of the heart is a tube,
white-coloured and exceedingly thick. Fishes in some few cases have an
oesophagus, as the conger and the eel; and in these the organ is
small.

In fishes that are furnished with an undivided liver, the organ
lies entirely on the right side; where the liver is cloven from the
root, the larger half of the organ is on the right side: for in some
fishes the two parts are detached from one another, without any
coalescence at the root, as is the case with the dogfish. And there is
also a species of hare in what is named the Fig district, near Lake
Bolbe, and elsewhere, which animal might be taken to have two livers
owing to the length of the connecting ducts, similar to the
structure in the lung of birds.

The spleen in all cases, when normally placed, is on the
left-hand side, and the kidneys also lie in the same position in all
creatures that possess them. There have been known instances of
quadrupeds under dissection, where the spleen was on the right hand
and the liver on the left; but all such cases are regarded as
supernatural.

In all animals the wind-pipe extends to the lung, and the
manner how, we shall discuss hereafter; and the oesophagus, in all
that have the organ, extends through the midriff into the stomach.
For, by the way, as has been observed, most fishes have no oesophagus,
but the stomach is united directly with the mouth, so that in some
cases when big fish are pursuing little ones, the stomach tumbles
forward into the mouth.

All the afore-mentioned animals have a stomach, and one
similarly situated, that is to say, situated directly under the
midriff; and they have a gut connected therewith and closing at the
outlet of the residuum and at what is termed the 'rectum'. However,
animals present diversities in the structure of their stomachs. In the
first place, of the viviparous quadrupeds, such of the horned
animals as are not equally furnished with teeth in both jaws are
furnished with four such chambers. These animals, by the way, are
those that are said to chew the cud. In these animals the oesophagus
extends from the mouth downwards along the lung, from the midriff to
the big stomach (or paunch); and this stomach is rough inside and
semi-partitioned. And connected with it near to the entry of the
oesophagus is what from its appearance is termed the 'reticulum' (or
honeycomb bag); for outside it is like the stomach, but inside it
resembles a netted cap; and the reticulum is a great deal smaller than
the stomach. Connected with this is the 'echinus' (or many-plies),
rough inside and laminated, and of about the same size as the
reticulum. Next after this comes what is called the 'enystrum' (or
abomasum), larger an longer than the echinus, furnished inside with
numerous folds or ridges, large and smooth. After all this comes the
gut.

Such is the stomach of those quadrupeds that are horned and have
an unsymmetrical dentition; and these animals differ one from
another in the shape and size of the parts, and in the fact of the
oesophagus reaching the stomach centralwise in some cases and sideways
in others. Animals that are furnished equally with teeth in both
jaws have one stomach; as man, the pig, the dog, the bear, the lion,
the wolf. (The Thos, by the by, has all its internal organs similar to
the wolf's. )

All these, then have a single stomach, and after that the gut;
but the stomach in some is comparatively large, as in the pig and
bear, and the stomach of the pig has a few smooth folds or ridges;
others have a much smaller stomach, not much bigger than the gut, as
the lion, the dog, and man. In the other animals the shape of the
stomach varies in the direction of one or other of those already
mentioned; that is, the stomach in some animals resembles that of
the pig; in others that of the dog, alike with the larger animals
and the smaller ones. In all these animals diversities occur in regard
to the size, the shape, the thickness or the thinness of the
stomach, and also in regard to the place where the oesophagus opens
into it.

There is also a difference in structure in the gut of the two
groups of animals above mentioned (those with unsymmetrical and
those with symmetrical dentition) in size, in thickness, and in
foldings.

The intestines in those animals whose jaws are unequally
furnished with teeth are in all cases the larger, for the animals
themselves are larger than those in the other category; for very few
of them are small, and no single one of the horned animals is very
small. And some possess appendages (or caeca) to the gut, but no
animal that has not incisors in both jaws has a straight gut.

The elephant has a gut constricted into chambers, so constructed
that the animal appears to have four stomachs; in it the food is
found, but there is no distinct and separate receptacle. Its viscera
resemble those of the pig, only that the liver is four times the
size of that of the ox, and the other viscera in like proportion,
while the spleen is comparatively small.

Much the same may be predicated of the properties of the
stomach and the gut in oviparous quadrupeds, as in the land
tortoise, the turtle, the lizard, both crocodiles, and, in fact, in
all animals of the like kind; that is to say, their stomach is one and
simple, resembling in some cases that of the pig, and in other cases
that of the dog.

The serpent genus is similar and in almost all respects furnished
similarly to the saurians among land animals, if one could only
imagine these saurians to be increased in length and to be devoid of
legs. That is to say, the serpent is coated with tessellated scutes,
and resembles the saurian in its back and belly; only, by the way,
it has no testicles, but, like fishes, has two ducts converging into
one, and an ovary long and bifurcate. The rest of its internal
organs are identical with those of the saurians, except that, owing to
the narrowness and length of the animal, the viscera are
correspondingly narrow and elongated, so that they are apt to escape
recognition from the similarities in shape. Thus, the windpipe of
the creature is exceptionally long, and the oesophagus is longer
still, and the windpipe commences so close to the mouth that the
tongue appears to be underneath it; and the windpipe seems to
project over the tongue, owing to the fact that the tongue draws
back into a sheath and does not remain in its place as in other
animals. The tongue, moreover, is thin and long and black, and can
be protruded to a great distance. And both serpents and saurians
have this altogether exceptional property in the tongue, that it is
forked at the outer extremity, and this property is the more marked in
the serpent, for the tips of his tongue are as thin as hairs. The
seal, also, by the way, has a split tongue.

The stomach of the serpent is like a more spacious gut,
resembling the stomach of the dog; then comes the gut, long, narrow,
and single to the end. The heart is situated close to the pharynx,
small and kidney-shaped; and for this reason the organ might in some
cases appear not to have the pointed end turned towards the breast.
Then comes the lung, single, and articulated with a membranous
passage, very long, and quite detached from the heart. The liver is
long and simple; the spleen is short and round: as is the case in both
respects with the saurians. Its gall resembles that of the fish; the
water-snakes have it beside the liver, and the other snakes have it
usually beside the gut. These creatures are all saw-toothed. Their
ribs are as numerous as the days of the month; in other words, they
are thirty in number.

Some affirm that the same phenomenon is observable with
serpents as with swallow chicks; in other words, they say that if
you prick out a serpent's eyes they will grow again. And further,
the tails of saurians and of serpents, if they be cut off, will grow
again.

With fishes the properties of the gut and stomach are similar;
that is, they have a stomach single and simple, but variable in
shape according to species. For in some cases the stomach is
gut-shaped, as with the scarus, or parrot-fish; which fish, by the
way, appears to be the only fish that chews the cud. And the whole
length of the gut is simple, and if it have a reduplication or kink it
loosens out again into a simple form.

An exceptional property in fishes and in birds for the most
part is the being furnished with gut-appendages or caeca. Birds have
them low down and few in number. Fishes have them high up about the
stomach, and sometimes numerous, as in the goby, the galeos, the
perch, the scorpaena, the citharus, the red mullet, and the sparus;
the cestreus or grey mullet has several of them on one side of the
belly, and on the other side only one. Some fish possess these
appendages but only in small numbers, as the hepatus and the
glaucus; and, by the way, they are few also in the dorado. These
fishes differ also from one another within the same species, for in
the dorado one individual has many and another few. Some fishes are
entirely without the part, as the majority of the selachians. As for
all the rest, some of them have a few and some a great many. And in
all cases where the gut-appendages are found in fish, they are found
close up to the stomach.

In regard to their internal parts birds differ from other animals
and from one another. Some birds, for instance, have a crop in front
of the stomach, as the barn-door cock, the cushat, the pigeon, and the
partridge; and the crop consists of a large hollow skin, into which
the food first enters and where it lies ingested. Just where the
crop leaves the oesophagus it is somewhat narrow; by and by it
broadens out, but where it communicates with the stomach it narrows
down again. The stomach (or gizzard) in most birds is fleshy and hard,
and inside is a strong skin which comes away from the fleshy part.
Other birds have no crop, but instead of it an oesophagus wide and
roomy, either all the way or in the part leading to the stomach, as
with the daw, the raven, and the carrion-crow. The quail also has
the oesophagus widened out at the lower extremity, and in the
aegocephalus and the owl the organ is slightly broader at the bottom
than at the top. The duck, the goose, the gull, the catarrhactes,
and the great bustard have the oesophagus wide and roomy from one
end to the other, and the same applies to a great many other birds. In
some birds there is a portion of the stomach that resembles a crop, as
in the kestrel. In the case of small birds like the swallow and the
sparrow neither the oesophagus nor the crop is wide, but the stomach
is long. Some few have neither a crop nor a dilated oesophagus, but
the latter is exceedingly long, as in long necked birds, such as the
porphyrio, and, by the way, in the case of all these birds the
excrement is unusually moist. The quail is exceptional in regard to
these organs, as compared with other birds; in other words, it has a
crop, and at the same time its oesophagus is wide and spacious in
front of the stomach, and the crop is at some distance, relatively
to its size, from the oesophagus at that part.

Further, in most birds, the gut is thin, and simple when loosened
out. The gut-appendages or caeca in birds, as has been observed, are
few in number, and are not situated high up, as in fishes, but low
down towards the extremity of the gut. Birds, then, have caeca-not
all, but the greater part of them, such as the barn-door cock, the
partridge, the duck, the night-raven, (the localus,) the ascalaphus,
the goose, the swan, the great bustard, and the owl. Some of the
little birds also have these appendages; but the caeca in their case
are exceedingly minute, as in the sparrow.

Book III

1

Now that we have stated the magnitudes, the properties, and the
relative differences of the other internal organs, it remains for us
to treat of the organs that contribute to generation. These organs
in the female are in all cases internal; in the male they present
numerous diversities.

In the blooded animals some males are altogether devoid of
testicles, and some have the organ but situated internally; and of
those males that have the organ internally situated, some have it
close to the loin in the neighbourhood of the kidney and others
close to the belly. Other males have the organ situated externally. In
the case of these last, the penis is in some cases attached to the
belly, whilst in others it is loosely suspended, as is the case also
with the testicles; and, in the cases where the penis is attached to
the belly, the attachment varies accordingly as the animal is
emprosthuretic or opisthuretic.

No fish is furnished with testicles, nor any other creature
that has gills, nor any serpent whatever: nor, in short, any animal
devoid of feet, save such only as are viviparous within themselves.
Birds are furnished with testicles, but these are internally situated,
close to the loin. The case is similar with oviparous quadrupeds, such
as the lizard, the tortoise and the crocodile; and among the
viviparous animals this peculiarity is found in the hedgehog. Others
among those creatures that have the organ internally situated have
it close to the belly, as is the case with the dolphin amongst animals
devoid of feet, and with the elephant among viviparous quadrupeds.
In other cases these organs are externally conspicuous.

We have already alluded to the diversities observed in the
attachment of these organs to the belly and the adjacent region; in
other words, we have stated that in some cases the testicles are
tightly fastened back, as in the pig and its allies, and that in
others they are freely suspended, as in man.

Fishes, then, are devoid of testicles, as has been stated, and
serpents also. They are furnished, however, with two ducts connected
with the midriff and running on to either side of the backbone,
coalescing into a single duct above the outlet of the residuum, and by
'above' the outlet I mean the region near to the spine. These ducts in
the rutting season get filled with the genital fluid, and, if the
ducts be squeezed, the sperm oozes out white in colour. As to the
differences observed in male fishes of diverse species, the reader
should consult my treatise on Anatomy, and the subject will be
hereafter more fully discussed when we describe the specific character
in each case.

The males of oviparous animals, whether biped or quadruped, are
in all cases furnished with testicles close to the loin underneath the
midriff. With some animals the organ is whitish, in others somewhat of
a sallow hue; in all cases it is entirely enveloped with minute and
delicate veins. From each of the two testicles extends a duct, and, as
in the case of fishes, the two ducts coalesce into one above the
outlet of the residuum. This constitutes the penis, which organ in the
case of small ovipara is inconspicuous; but in the case of the
larger ovipara, as in the goose and the like, the organ becomes
quite visible just after copulation.

The ducts in the case of fishes and in biped and quadruped
ovipara are attached to the loin under the stomach and the gut, in
betwixt them and the great vein, from which ducts or blood-vessels
extend, one to each of the two testicles. And just as with fishes
the male sperm is found in the seminal ducts, and the ducts become
plainly visible at the rutting season and in some instances become
invisible after the season is passed, so also is it with the testicles
of birds; before the breeding season the organ is small in some
birds and quite invisible in others, but during the season the organ
in all cases is greatly enlarged. This phenomenon is remarkably
illustrated in the ring-dove and the partridge, so much so that some
people are actually of opinion that these birds are devoid of the
organ in the winter-time.

Of male animals that have their testicles placed frontwards, some
have them inside, close to the belly, as the dolphin; some have them
outside, exposed to view, close to the lower extremity of the belly.
These animals resemble one another thus far in respect to this
organ; but they differ from one another in this fact, that some of
them have their testicles situated separately by themselves, while
others, which have the organ situated externally, have them
enveloped in what is termed the scrotum.

Again, in all viviparous animals furnished with feet the
following properties are observed in the testicles themselves. From
the aorta there extend vein-like ducts to the head of each of the
testicles, and another two from the kidneys; these two from the
kidneys are supplied with blood, while the two from the aorta are
devoid of it. From the head of the testicle alongside of the
testicle itself is a duct, thicker and more sinewy than the other just
alluded to-a duct that bends back again at the end of the testicle
to its head; and from the head of each of the two testicles the two
ducts extend until they coalesce in front at the penis. The duct
that bends back again and that which is in contact with the testicle
are enveloped in one and the same membrane, so that, until you draw
aside the membrane, they present all the appearance of being a
single undifferentiated duct. Further, the duct in contact with the
testicle has its moist content qualified by blood, but to a
comparatively less extent than in the case of the ducts higher up
which are connected with the aorta; in the ducts that bend back
towards the tube of the penis, the liquid is white-coloured. There
also runs a duct from the bladder, opening into the upper part of
the canal, around which lies, sheathwise, what is called the 'penis'.

All these descriptive particulars may be regarded by the light of
the accompanying diagram; wherein the letter A marks the
starting-point of the ducts that extend from the aorta; the letters KK
mark the heads of the testicles and the ducts descending thereunto;
the ducts extending from these along the testicles are marked MM; the
ducts turning back, in which is the white fluid, are marked BB; the
penis D; the bladder E; and the testicles XX.

(By the way, when the testicles are cut off or removed, the ducts
draw upwards by contraction. Moreover, when male animals are young,
their owner sometimes destroys the organ in them by attrition;
sometimes they castrate them at a later period. And I may here add,
that a bull has been known to serve a cow immediately after
castration, and actually to impregnate her. )

So much then for the properties of testicles in male animals.

In female animals furnished with a womb, the womb is not in all
cases the same in form or endowed with the same properties, but both
in the vivipara and the ovipara great diversities present
themselves.
In all creatures that have the womb close to the genitals,
the womb is two-horned, and one horn lies to the right-hand side and
the other to the left; its commencement, however, is single, and so is
the orifice, resembling in the case of the most numerous and largest
animals a tube composed of much flesh and gristle. Of these parts
one is termed the hystera or delphys, whence is derived the word
adelphos, and the other part, the tube or orifice, is termed metra. In
all biped or quadruped vivipara the womb is in all cases below the
midriff, as in man, the dog, the pig, the horse, and the ox; the
same is the case also in all horned animals. At the extremity of the
so-called ceratia, or horns, the wombs of most animals have a twist or
convolution.

In the case of those ovipara that lay eggs externally, the wombs
are not in all cases similarly situated. Thus the wombs of birds are
close to the midriff, and the wombs of fishes down below, just like
the wombs of biped and quadruped vivipara, only that, in the case of
the fish, the wombs are delicately formed, membranous, and
elongated; so much so that in extremely small fish, each of the two
bifurcated parts looks like a single egg, and those fishes whose egg
is described as crumbling would appear to have inside them a pair of
eggs, whereas in reality each of the two sides consists not of one but
of many eggs, and this accounts for their breaking up into so many
particles.

The womb of birds has the lower and tubular portion fleshy and
firm, and the part close to the midriff membranous and exceedingly
thin and fine: so thin and fine that the eggs might seem to be outside
the womb altogether. In the larger birds the membrane is more
distinctly visible, and, if inflated through the tube, lifts and
swells out; in the smaller birds all these parts are more indistinct.

The properties of the womb are similar in oviparous quadrupeds, as
the tortoise, the lizard, the frog and the like; for the tube below is
single and fleshy, and the cleft portion with the eggs is at the top
close to the midriff. With animals devoid of feet that are
internally oviparous and viviparous externally, as is the case with
the dogfish and the other so-called Selachians (and by this title we
designate such creatures destitute of feet and furnished with gills as
are viviparous), with these animals the womb is bifurcate, and
beginning down below it extends as far as the midriff, as in the
case of birds. There is also a narrow part between the two horns
running up as far as the midriff, and the eggs are engendered here and
above at the origin of the midriff; afterwards they pass into the
wider space and turn from eggs into young animals. However, the
differences in respect to the wombs of these fishes as compared with
others of their own species or with fishes in general, would be more
satisfactorily studied in their various forms in specimens under
dissection.

The members of the serpent genus also present divergencies either
when compared with the above-mentioned creatures or with one
another. Serpents as a rule are oviparous, the viper being the only
viviparous member of the genus. The viper is, previously to external
parturition, oviparous internally; and owing to this perculiarity
the properties of the womb in the viper are similar to those of the
womb in the selachians. The womb of the serpent is long, in keeping
with the body, and starting below from a single duct extends
continuously on both sides of the spine, so as to give the
impression of thus being a separate duct on each side of the spine,
until it reaches the midriff, where the eggs are engendered in a
row; and these eggs are laid not one by one, but all strung
together. (And all animals that are viviparous both internally and
externally have the womb situated above the stomach, and all the
ovipara underneath, near to the loin. Animals that are viviparous
externally and internally oviparous present an intermediate
arrangement; for the underneath portion of the womb, in which the eggs
are, is placed near to the loin, but the part about the orifice is
above the gut. )

Further, there is the following diversity observable in wombs as
compared with one another: namely that the females of horned
nonambidental animals are furnished with cotyledons in the womb when
they are pregnant, and such is the case, among ambidentals, with the
hare, the mouse, and the bat; whereas all other animals that are
ambidental, viviparous, and furnished with feet, have the womb quite
smooth, and in their case the attachment of the embryo is to the
womb itself and not to any cotyledon inside it.

The parts, then, in animals that are not homogeneous with
themselves and uniform in their texture, both parts external and parts
internal, have the properties above assigned to them.

2

In sanguineous animals the homogeneous or uniform part most
universally found is the blood, and its habitat the vein; next in
degree of universality, their analogues, lymph and fibre, and, that
which chiefly constitutes the frame of animals, flesh and whatsoever
in the several parts is analogous to flesh; then bone, and parts
that are analogous to bone, as fish-bone and gristle; and then, again,
skin, membrane, sinew, hair, nails, and whatever corresponds to these;
and, furthermore, fat, suet, and the excretions: and the excretions
are dung, phlegm, yellow bile, and black bile.

Now, as the nature of blood and the nature of the veins have
all the appearance of being primitive, we must discuss their
properties first of all, and all the more as some previous writers
have treated them very unsatisfactorily. And the cause of the
ignorance thus manifested is the extreme difficulty experienced in the
way of observation. For in the dead bodies of animals the nature of
the chief veins is undiscoverable, owing to the fact that they
collapse at once when the blood leaves them; for the blood pours out
of them in a stream, like liquid out of a vessel, since there is no
blood separately situated by itself, except a little in the heart, but
it is all lodged in the veins. In living animals it is impossible to
inspect these parts, for of their very nature they are situated inside
the body and out of sight. For this reason anatomists who have carried
on their investigations on dead bodies in the dissecting room have
failed to discover the chief roots of the veins, while those who
have narrowly inspected bodies of living men reduced to extreme
attenuation have arrived at conclusions regarding the origin of the
veins from the manifestations visible externally. Of these
investigators, Syennesis, the physician of Cyprus, writes as follows:-

'The big veins run thus:-from the navel across the loins, along
the back, past the lung, in under the breasts; one from right to left,
and the other from left to right; that from the left, through the
liver to the kidney and the testicle, that from the right, to the
spleen and kidney and testicle, and from thence to the penis. '
Diogenes of Apollonia writes thus:-

'The veins in man are as follows:-There are two veins
pre-eminent in magnitude. These extend through the belly along the
backbone, one to right, one to left; either one to the leg on its
own side, and upwards to the head, past the collar bones, through
the throat. From these, veins extend all over the body, from that on
the right hand to the right side and from that on the left hand to the
left side; the most important ones, two in number, to the heart in the
region of the backbone; other two a little higher up through the chest
in underneath the armpit, each to the hand on its side: of these
two, one being termed the vein splenitis, and the other the vein
hepatitis. Each of the pair splits at its extremity; the one
branches in the direction of the thumb and the other in the
direction of the palm; and from these run off a number of minute veins
branching off to the fingers and to all parts of the hand. Other
veins, more minute, extend from the main veins; from that on the right
towards the liver, from that on the left towards the spleen and the
kidneys. The veins that run to the legs split at the juncture of the
legs with the trunk and extend right down the thigh. The largest of
these goes down the thigh at the back of it, and can be discerned
and traced as a big one; the second one runs inside the thigh, not
quite as big as the one just mentioned. After this they pass on
along the knee to the shin and the foot (as the upper veins were
described as passing towards the hands), and arrive at the sole of the
foot, and from thence continue to the toes. Moreover, many delicate
veins separate off from the great veins towards the stomach and
towards the ribs.

'The veins that run through the throat to the head can be
discerned and traced in the neck as large ones; and from each one of
the two, where it terminates, there branch off a number of veins to
the head; some from the right side towards the left, and some from the
left side towards the right; and the two veins terminate near to
each of the two ears. There is another pair of veins in the neck
running along the big vein on either side, slightly less in size
than the pair just spoken of, and with these the greater part of the
veins in the head are connected. This other pair runs through the
throat inside; and from either one of the two there extend veins in
underneath the shoulder blade and towards the hands; and these
appear alongside the veins splenitis and hepatitis as another pair
of veins smaller in size. When there is a pain near the surface of the
body, the physician lances these two latter veins; but when the pain
is within and in the region of the stomach he lances the veins
splenitis and hepatitis. And from these, other veins depart to run
below the breasts.

'There is also another pair running on each side through the
spinal marrow to the testicles, thin and delicate. There is,
further, a pair running a little underneath the cuticle through the
flesh to the kidneys, and these with men terminate at the testicle,
and with women at the womb. These veins are termed the spermatic
veins. The veins that leave the stomach are comparatively broad just
as they leave; but they become gradually thinner, until they change
over from right to left and from left to right.

'Blood is thickest when it is imbibed by the fleshy parts; when
it is transmitted to the organs above-mentioned, it becomes thin,
warm, and frothy. '

3

Such are the accounts given by Syennesis and Diogenes. Polybus
writes to the following effect:-

'There are four pairs of veins. The first extends from the back of
the head, through the neck on the outside, past the backbone on either
side, until it reaches the loins and passes on to the legs, after
which it goes on through the shins to the outer side of the ankles and
on to the feet. And it is on this account that surgeons, for pains
in the back and loin, bleed in the ham and in the outer side of the
ankle. Another pair of veins runs from the head, past ears, through
the neck; which veins are termed the jugular veins. This pair goes
on inside along the backbone, past the muscles of the loins, on to the
testicles, and onwards to the thighs, and through the inside of the
hams and through the shins down to the inside of the ankles and to the
feet; and for this reason, surgeons, for pains in the muscles of the
loins and in the testicles, bleed on the hams and the inner side of
the ankles. The third pair extends from the temples, through the neck,
in underneath the shoulder-blades, into the lung; those from right
to left going in underneath the breast and on to the spleen and the
kidney; those from left to right running from the lung in underneath
the breast and into the liver and the kidney; and both terminate in
the fundament. The fourth pair extend from the front part of the
head and the eyes in underneath the neck and the collar-bones; from
thence they stretch on through the upper part of the upper arms to the
elbows and then through the fore-arms on to the wrists and the
jointings of the fingers, and also through the lower part of the
upper-arms to the armpits, and so on, keeping above the ribs, until
one of the pair reaches the spleen and the other reaches the liver;
and after this they both pass over the stomach and terminate at the
penis. '

The above quotations sum up pretty well the statements of all
previous writers. Furthermore, there are some writers on Natural
History who have not ventured to lay down the law in such precise
terms as regards the veins, but who all alike agree in assigning the
head and the brain as the starting-point of the veins. And in this
opinion they are mistaken.

The investigation of such a subject, as has been remarked, is one
fraught with difficulties; but, if any one be keenly interested in the
matter, his best plan will be to allow his animals to starve to
emaciation, then to strangle them on a sudden, and thereupon to
prosecute his investigations.

We now proceed to give particulars regarding the properties and
functions of the veins. There are two blood-vessels in the thorax by
the backbone, and lying to its inner side; and of these two the larger
one is situated to the front, and the lesser one is to the rear of it;
and the larger is situated rather to the right hand side of the
body, and the lesser one to the left; and by some this vein is
termed the 'aorta', from the fact that even in dead bodies part of
it is observed to be full of air. These blood-vessels have their
origins in the heart, for they traverse the other viscera, in whatever
direction they happen to run, without in any way losing their
distinctive characteristic as blood-vessels, whereas the heart is as
it were a part of them (and that too more in respect to the
frontward and larger one of the two), owing to the fact that these two
veins are above and below, with the heart lying midway.

The heart in all animals has cavities inside it. In the case of
the smaller animals even the largest of the chambers is scarcely
discernible; the second larger is scarcely discernible in animals of
medium size; but in the largest animals all three chambers are
distinctly seen. In the heart then (with its pointed end directed
frontwards, as has been observed) the largest of the three chambers is
on the right-hand side and highest up; the least one is on the
left-hand side; and the medium-sized one lies in betwixt the other
two; and the largest one of the three chambers is a great deal
larger than either of the two others. All three, however, are
connected with passages leading in the direction of the lung, but
all these communications are indistinctly discernible by reason of
their minuteness, except one.

The great blood-vessel, then, is attached to the biggest of the
three chambers, the one that lies uppermost and on the right-hand
side; it then extends right through the chamber, coming out as
blood-vessel again; just as though the cavity of the heart were a part
of the vessel, in which the blood broadens its channel as a river that
widens out in a lake. The aorta is attached to the middle chamber;
only, by the way, it is connected with it by much narrower pipe.

The great blood-vessel then passes through the heart (and runs
from the heart into the aorta). The great vessel looks as though
made of membrane or skin, while the aorta is narrower than it, and
is very sinewy; and as it stretches away to the head and to the
lower parts it becomes exceedingly narrow and sinewy.

First of all, then, upwards from the heart there stretches a
part of the great blood-vessel towards the lung and the attachment
of the aorta, a part consisting of a large undivided vessel. But there
split off from it two parts; one towards the lung and the other
towards the backbone and the last vertebra of the neck.

The vessel, then, that extends to the lung, as the lung itself
is duplicate, divides at first into two; and then extends along by
every pipe and every perforation, greater along the greater ones,
lesser along the less, so continuously that it is impossible to
discern a single part wherein there is not perforation and vein; for
the extremities are indistinguishable from their minuteness, and in
point of fact the whole lung appears to be filled with blood.

The branches of the blood-vessels lie above the tubes that
extend from the windpipe. And that vessel which extends to the
vertebra of the neck and the backbone, stretches back again along
the backbone; as Homer represents in the lines:-

(Antilochus, as Thoon turned him round),

Transpierc'd his back with a dishonest wound;

The hollow vein that to the neck extends,

Along the chine, the eager javelin rends.

From this vessel there extend small blood-vessels at each rib
and each vertebra; and at the vertebra above the kidneys the vessel
bifurcates. And in the above way the parts branch off from the great
blood-vessel.

But up above all these, from that part which is connected with the
heart, the entire vein branches off in two directions. For its
branches extend to the sides and to the collarbones, and then pass on,
in men through the armpits to the arms, in quadrupeds to the forelegs,
in birds to the wings, and in fishes to the upper or pectoral fins.
(See diagram. ) The trunks of these veins, where they first branch
off, are called the 'jugular' veins; and, where they branch off to
the neck the great vein run alongside the windpipe; and,
occasionally, if these veins are pressed externally, men, though not
actually choked, become insensible, shut their eyes, and fall flat on
the ground. Extending in the way described and keeping the windpipe
in betwixt them, they pass on until they reach the ears at the
junction of the lower jaw with the skull. Hence again they branch off
into four veins, of which one bends back and descends through the
neck and the shoulder, and meets the previous branching off of the
vein at the bend of the arm, while the rest of it terminates at the
hand and fingers. (See diagram. )

Each vein of the other pair stretches from the region of the ear
to the brain, and branches off in a number of fine and delicate
veins into the so-called meninx, or membrane, which surrounds the
brain. The brain itself in all animals is destitute of blood, and no
vein, great or small, holds its course therein. But of the remaining
veins that branch off from the last mentioned vein some envelop the
head, others close their courses in the organs of sense and at the
roots of the teeth in veins exceedingly fine and minute.

4

And in like manner the parts of the lesser one of the two chief
blood-vessels, designated the aorta, branch off, accompanying the
branches from the big vein; only that, in regard to the aorta, the
passages are less in size, and the branches very considerably less
than are those of the great vein. So much for the veins as observed in
the regions above the heart.

The part of the great vein that lies underneath the heart
extends, freely suspended, right through the midriff, and is united
both to the aorta and the backbone by slack membranous communications.
From it one vein, short and wide, extends through the liver, and
from it a number of minute veins branch off into the liver and
disappear. From the vein that passes through the liver two branches
separate off, of which one terminates in the diaphragm or so-called
midriff, and the other runs up again through the armpit into the right
arm and unites with the other veins at the inside of the bend of the
arm; and it is in consequence of this local connexion that, when the
surgeon opens this vein in the forearm, the patient is relieved of
certain pains in the liver; and from the left-hand side of it there
extends a short but thick vein to the spleen and the little veins
branching off it disappear in that organ. Another part branches off
from the left-hand side of the great vein, and ascends, by a course
similar to the course recently described, into the left arm; only that
the ascending vein in the one case is the vein that traverses the
liver, while in this case it is distinct from the vein that runs
into the spleen. Again, other veins branch off from the big vein;
one to the omentum, and another to the pancreas, from which vein run a
number of veins through the mesentery. All these veins coalesce in a
single large vein, along the entire gut and stomach to the oesophagus;
about these parts there is a great ramification of branch veins.

As far as the kidneys, each of the two remaining undivided, the
aorta and the big vein extend; and here they get more closely attached
to the backbone, and branch off, each of the two, into a A shape,
and the big vein gets to the rear of the aorta. But the chief
attachment of the aorta to the backbone takes place in the region of
the heart; and the attachment is effected by means of minute and
sinewy vessels. The aorta, just as it draws off from the heart, is a
tube of considerable volume, but, as it advances in its course, it
gets narrower and more sinewy. And from the aorta there extend veins
to the mesentery just like the veins that extend thither from the
big vein, only that the branches in the case of the aorta are
considerably less in magnitude; they are, indeed, narrow and
fibrillar, and they end in delicate hollow fibre-like veinlets.

There is no vessel that runs from the aorta into the liver or
the spleen.

From each of the two great blood-vessels there extend branches
to each of the two flanks, and both branches fasten on to the bone.
Vessels also extend to the kidneys from the big vein and the aorta;
only that they do not open into the cavity of the organ, but their
ramifications penetrate into its substance. From the aorta run two
other ducts to the bladder, firm and continuous; and there are other
ducts from the hollow of the kidneys, in no way communicating with the
big vein. From the centre of each of the two kidneys springs a
hollow sinewy vein, running along the backbone right through the
loins; by and by each of the two veins first disappears in its own
flank, and soon afterwards reappears stretching in the direction of
the flank. The extremities of these attach to the bladder, and also in
the male to the penis and in the female to the womb. From the big vein
no vein extends to the womb, but the organ is connected with the aorta
by veins numerous and closely packed.

Furthermore, from the aorta and the great vein at the points of
divarication there branch off other veins. Some of these run to the
groins-large hollow veins-and then pass on down through the legs and
terminate in the feet and toes. And, again, another set run through
the groins and the thighs cross-garter fashion, from right to left and
from left to right, and unite in the hams with the other veins.

In the above description we have thrown light upon the course of
the veins and their points of departure.

In all sanguineous animals the case stands as here set forth in
regard to the points of departure and the courses of the chief
veins. But the description does not hold equally good for the entire
vein-system in all these animals. For, in point of fact, the organs
are not identically situated in them all; and, what is more, some
animals are furnished with organs of which other animals are
destitute. At the same time, while the description so far holds
good, the proof of its accuracy is not equally easy in all cases,
but is easiest in the case of animals of considerable magnitude and
supplied abundantly with blood. For in little animals and those
scantily supplied with blood, either from natural and inherent
causes or from a prevalence of fat in the body, thorough accuracy in
investigation is not equally attainable; for in the latter of these
creatures the passages get clogged, like water-channels choked with
slush; and the others have a few minute fibres to serve instead of
veins. But in all cases the big vein is plainly discernible, even in
creatures of insignificant size.

5

The sinews of animals have the following properties. For these
also the point of origin is the heart; for the heart has sinews within
itself in the largest of its three chambers, and the aorta is a
sinew-like vein; in fact, at its extremity it is actually a sinew, for
it is there no longer hollow, and is stretched like the sinews where
they terminate at the jointings of the bones. Be it remembered,
however, that the sinews do not proceed in unbroken sequence from
one point of origin, as do the blood-vessels.

For the veins have the shape of the entire body, like a sketch
of a mannikin; in such a way that the whole frame seems to be filled
up with little veins in attenuated subjects-for the space occupied
by flesh in fat individuals is filled with little veins in thin
ones-whereas the sinews are distributed about the joints and the
flexures of the bones. Now, if the sinews were derived in unbroken
sequence from a common point of departure, this continuity would be
discernible in attenuated specimens.

In the ham, or the part of the frame brought into full play in the
effort of leaping, is an important system of sinews; and another
sinew, a double one, is that called 'the tendon', and others are those
brought into play when a great effort of physical strength is
required; that is to say, the epitonos or back-stay and the
shoulder-sinews. Other sinews, devoid of specific designation, are
situated in the region of the flexures of the bones; for all the bones
that are attached to one another are bound together by sinews, and a
great quantity of sinews are placed in the neighbourhood of all the
bones. Only, by the way, in the head there is no sinew; but the head
is held together by the sutures of the bones.

Sinew is fissile lengthwise, but crosswise it is not easily
broken, but admits of a considerable amount of hard tension. In
connexion with sinews a liquid mucus is developed, white and
glutinous, and the organ, in fact, is sustained by it and appears to
be substantially composed of it. Now, vein may be submitted to the
actual cautery, but sinew, when submitted to such action, shrivels
up altogether; and, if sinews be cut asunder, the severed parts will
not again cohere. A feeling of numbness is incidental only to parts of
the frame where sinew is situated.

There is a very extensive system of sinews connected severally
with the feet, the hands, the ribs, the shoulder-blades, the neck, and
the arms.

All animals supplied with blood are furnished with sinews; but
in the case of animals that have no flexures to their limbs, but
are, in fact, destitute of either feet or hands, the sinews are fine
and inconspicuous; and so, as might have been anticipated, the
sinews in the fish are chiefly discernible in connexion with the fin.

6

The ines (or fibrous connective tissue) are a something
intermediate between sinew and vein. Some of them are supplied with
fluid, the lymph; and they pass from sinew to vein and from vein to
sinew. There is another kind of ines or fibre that is found in
blood, but not in the blood of all animals alike. If this fibre be
left in the blood, the blood will coagulate; if it be removed or
extracted, the blood is found to be incapable of coagulation. While,
however, this fibrous matter is found in the blood of the great
majority of animals, it is not found in all. For instance, we fail
to find it in the blood of the deer, the roe, the antelope, and some
other animals; and, owing to this deficiency of the fibrous tissue,
the blood of these animals does not coagulate to the extent observed
in the blood of other animals. The blood of the deer coagulates to
about the same extent as that of the hare: that is to the blood in
either case coagulates, but not into a stiff or jelly-like
substance, like the blood of ordinary animals, but only into a flaccid
consistency like that of milk which is not subjected to the action
of rennet. The blood of the antelope admits of a firmer consistency in
coagulation; for in this respect it resembles, or only comes a
little short of, the blood of sheep. Such are the properties of
vein, sinew, and fibrous tissue.

7

The bones in animals are all connected with one single bone, and
are interconnected, like the veins, in one unbroken sequence; and
there is no instance of a bone standing apart by itself. In all
animals furnished with bones, the spine or backbone is the point of
origin for the entire osseous system. The spine is composed of
vertebrae, and it extends from the head down to the loins. The
vertebrae are all perforated, and, above, the bony portion of the head
is connected with the topmost vertebrae, and is designated the
'skull'. And the serrated lines on the skull are termed 'sutures'.

The skull is not formed alike in all animals. In some animals
the skull consists of one single undivided bone, as in the case of the
dog; in others it is composite in structure, as in man; and in the
human species the suture is circular in the female, while in the
male it is made up of three separate sutures, uniting above in
three-corner fashion; and instances have been known of a man's skull
being devoid of suture altogether. The skull is composed not of four
bones, but of six; two of these are in the region of the ears, small
in comparison with the other four. From the skull extend the jaws,
constituted of bone. (Animals in general move the lower jaw; the river
crocodile is the only animal that moves the upper one. ) In the jaws is
the tooth-system; and the teeth are constituted of bone, and are
half-way perforated; and the bone in question is the only kind of bone
which it is found impossible to grave with a graving tool.

On the upper part of the course of the backbone are the
collar-bones and the ribs. The chest rests on ribs; and these ribs
meet together, whereas the others do not; for no animal has bone in
the region of the stomach. Then come the shoulder-bones, or
blade-bones, and the arm-bones connected with these, and the bones
in the hands connected with the bones of the arms. With animals that
have forelegs, the osseous system of the foreleg resembles that of the
arm in man.

Below the level of the backbone, after the haunch-bone, comes
the hip-socket; then the leg-bones, those in the thighs and those in
the shins, which are termed colenes or limb-bones, a part of which
is the ankle, while a part of the same is the so-called 'plectrum'
in those creatures that have an ankle; and connected with these
bones are the bones in the feet.

Now, with all animals that are supplied with blood and furnished
with feet, and are at the same time viviparous, the bones do not
differ greatly one from another, but only in the way of relative
hardness, softness, or magnitude. A further difference, by the way, is
that in one and the same animal certain bones are supplied with
marrow, while others are destitute of it. Some animals might on casual
observation appear to have no marrow whatsoever in their bones: as
is the case with the lion, owing to his having marrow only in small
amount, poor and thin, and in very few bones; for marrow is found in
his thigh and armbones. The bones of the lion are exceptionally
hard; so hard, in fact, that if they are rubbed hard against one
another they emit sparks like flint-stones. The dolphin has bones, and
not fish-spine.

Of the other animals supplied with blood, some differ but
little, as is the case with birds; others have systems analogous, as
fishes; for viviparous fishes, such as the cartilaginous species,
are gristle-spined, while the ovipara have a spine which corresponds
to the backbone in quadrupeds. This exceptional property has been
observed in fishes, that in some of them there are found delicate
spines scattered here and there throughout the fleshy parts. The
serpent is similarly constructed to the fish; in other words, his
backbone is spinous. With oviparous quadrupeds, the skeleton of the
larger ones is more or less osseous; of the smaller ones, more or less
spinous. But all sanguineous animals have a backbone of either one
kind or other: that is, composed either of bone or of spine.

The other portions of the skeleton are found in some animals and
not found in others, but the presence or the absence of this and
that part carries with it, as a matter of course, the presence or
the absence of the bones or the spines corresponding to this or that
part. For animals that are destitute of arms and legs cannot be
furnished with limb-bones: and in like manner with animals that have
the same parts, but yet have them unlike in form; for in these animals
the corresponding bones differ from one another in the way of relative
excess or relative defect, or in the way of analogy taking the place
of identity. So much for the osseous or spinous systems in animals.

8

Gristle is of the same nature as bone, but differs from it in
the way of relative excess or relative defect. And just like bone,
cartilage also, if cut, does not grow again. In terrestrial viviparous
sanguinea the gristle formations are unperforated, and there is no
marrow in them as there is in bones; in the selachia, however--for, be
it observed, they are gristle-spined--there is found in the case of
the flat space in the region of the backbone, a gristle-like substance
analogous to bone, and in this gristle-like substance there is a
liquid resembling marrow. In viviparous animals furnished with feet,
gristle formations are found in the region of the ears, in the
nostrils, and around certain extremities of the bones.

9

Furthermore, there are parts of other kinds, neither identical
with, nor altogether diverse from, the parts above enumerated: such as
nails, hooves, claws, and horns; and also, by the way, beaks, such
as birds are furnished with-all in the several animals that are
furnished therewithal. All these parts are flexible and fissile; but
bone is neither flexible nor fissile, but frangible.

And the colours of horns and nails and claw and hoof follow the
colour of the skin and the hair. For according as the skin of an
animal is black, or white, or of medium hue, so are the horns, the
claws, or the hooves, as the case may be, of hue to match. And it is
the same with nails. The teeth, however, follow after the bones.
Thus in black men, such as the Aethiopians and the like, the teeth and
bones are white, but the nails are black, like the whole of the skin.

Horns in general are hollow at their point of attachment to the
bone which juts out from the head inside the horn, but they have a
solid portion at the tip, and they are simple and undivided in
structure. In the case of the stag alone of all animals the horns
are solid throughout, and ramify into branches (or antlers). And,
whereas no other animal is known to shed its horns, the deer sheds its
horns annually, unless it has been castrated; and with regard to the
effects of castration in animals we shall have much to say
hereafter. Horns attach rather to the skin than to the bone; which
will account for the fact that there are found in Phrygia and
elsewhere cattle that can move their horns as freely as their ears.

Of animals furnished with nails-and, by the way, all animals
have nails that have toes, and toes that have feet, except the
elephant; and the elephant has toes undivided and slightly
articulated, but has no nails whatsoever--of animals furnished with
nails, some are straight-nailed, like man; others are crooked
nailed, as the lion among animals that walk, and the eagle among
animals that fly.

10

The following are the properties of hair and of parts analogous to
hair, and of skin or hide. All viviparous animals furnished with
feet have hair; all oviparous animals furnished with feet have
horn-like tessellates; fishes, and fishes only, have scales-that is,
such oviparous fishes as have the crumbling egg or roe. For of the
lanky fishes, the conger has no such egg, nor the muraena, and the eel
has no egg at all.

The hair differs in the way of thickness and fineness, and of
length, according to the locality of the part in which it is found,
and according to the quality of skin or hide on which it grows. For,
as a general rule, the thicker the hide, the harder and the thicker is
the hair; and the hair is inclined to grow in abundance and to a great
length in localities of the bodies hollow and moist, if the localities
be fitted for the growth of hair at all. The facts are similar in
the case of animals whether coated with scales or with tessellates.
With soft-haired animals the hair gets harder with good feeding, and
with hard-haired or bristly animals it gets softer and scantier from
the same cause. Hair differs in quality also according to the relative
heat or warmth of the locality: just as the hair in man is hard in
warm places and soft in cold ones. Again, straight hair is inclined to
be soft, and curly hair to be bristly.

11

Hair is naturally fissile, and in this respect it differs in
degree in diverse animals. In some animals the hair goes on
gradually hardening into bristle until it no longer resembles hair but
spine, as in the case of the hedgehog. And in like manner with the
nails; for in some animals the nail differs as regards solidity in
no way from bone.

Of all animals man has the most delicate skin: that is, if we take
into consideration his relative size. In the skin or hide of all
animals there is a mucous liquid, scanty in some animals and plentiful
in others, as, for instance, in the hide of the ox; for men
manufacture glue out of it. (And, by the way, in some cases glue is
manufactured from fishes also. ) The skin, when cut, is in itself
devoid of sensation; and this is especially the case with the skin
on the head, owing to there being no flesh between it and the skull.
And wherever the skin is quite by itself, if it be cut asunder, it
does not grow together again, as is seen in the thin part of the
jaw, in the prepuce, and the eyelid. In all animals the skin is one of
the parts that extends continuous and unbroken, and it comes to a stop
only where the natural ducts pour out their contents, and at the mouth
and nails.