of desire is the pleasant. The part, however, by which food produces
the sensation is not precisely alike in all of them, but while in some
it is free from attachments, in others, where it is not required for
vocal pur, poses, it is adherent. In some again it is hard, in
others soft or flesh-like. Thus even the Crustacea, the Carabi for
instance and the like, and the Cephalopods, such as the Sepias and the
Poulps, have some such part inside the mouth. As for the Insects, some
of them have the part which serves as tongue inside the mouth, as is
the case with ants, and as is also the case with many Testacea,
while in others it is placed externally. In this latter case it
resembles a sting, and is hollow and spongy, so as to serve at one and
the same time for the tasting and for the sucking up of nutriment.
This is plainly to be seen in flies and bees and all such animals, and
likewise in some of the Testacea. In the Purpurae, for instance, so
strong is this part that it enables them to bore holes through the
hard covering of shell-fish, of the spiral snails, for example, that
are used as bait to catch them. So also the gad-flies and cattle-flies
can pierce through the skin of man, and some of them even through
the skins of other animals. Such, then, in these animals is the nature
of the tongue, which is thus as it were the counterpart of the
elephant's nostril. For as in the elephant the nostril is used as a
weapon, so in these animals the tongue serves as a sting.
In all other animals the tongue agrees with description already
given.
Book III
1
WE have next to consider the teeth, and with these the mouth, that
is the cavity which they enclose and form. The teeth have one
invariable office, namely the reduction of food; but besides this
general function they have other special ones, and these differ in
different groups. Thus in some animals the teeth serve as weapons; but
this with a distinction. For there are offensive weapons and there are
defensive weapons; and while in some animals, as the wild Carnivora,
the teeth answer both purposes, in many others, both wild and
domesticated, they serve only for defence. In man the teeth are
admirably constructed for their general office, the front ones being
sharp, so as to cut the food into bits, and the hinder ones broad
and flat, so as to grind it to a pulp; while between these and
separating them are the dog-teeth, which, in accordance with the
rule that the mean partakes of both extremes, share in the
characters of those on either side, being broad in one part but
sharp in another. Similar distinctions of shape are presented by the
teeth of other animals, with the exception of those whose teeth are
one and all of the sharp kind. In man, however, the number and the
character even of these sharp teeth have been mainly determined by the
requirements of speech. For the front teeth of man contribute in
many ways to the formation of letter-sounds.
In some animals, however, the teeth, as already said, serve merely
for the reduction of food. When, besides this, they serve as offensive
and defensive weapons, they may either be formed into tusks, as for
instance is the case in swine, or may be sharp-pointed and interlock
with those of the opposite jaw, in which case the animal is said to be
saw-toothed. The explanation of this latter arrangement is as follows.
The strength of such an animal is in its teeth, and these depend for
their efficiency on their sharpness. In order, then, to prevent
their getting blunted by mutual friction, such of them as serve for
weapons fit into each other's interspaces, and are so kept in proper
condition. No animal that has sharp interfitting teeth is at the
same time furnished with tusks. For nature never makes anything
superfluous or in vain. She gives, therefore, tusks to such animals as
strike in fighting, and serrated teeth to such as bite. Sows, for
instance, have no tusks, and accordingly sows bite instead of
striking.
A general principle must here be noted, which will be found
applicable not only in this instance but in many others that will
occur later on. Nature allots each weapon, offensive and defensive
alike, to those animals alone that can use it; or, if not to them
alone, to them in a more marked degree; and she allots it in its
most perfect state to those that can use it best; and this whether
it be a sting, or a spur, or horns, or tusks, or what it may of a like
kind.
Thus as males are stronger and more choleric than females, it is
in males that such parts as those just mentioned are found, either
exclusively, as in some species, or more fully developed, as in
others. For though females are of course provided with such parts as
are no less necessary to them than to males, the parts, for
instance, which subserve nutrition, they have even these in an
inferior degree, and the parts which answer no such necessary
purpose they do not possess at all. This explains why stags have
horns, while does have none; why the horns of cows are different
from those of bulls, and, similarly, the horns of ewes from those of
rams. It explains also why the females are often without spurs in
species where the males are provided with them, and accounts for
similar facts relating to all other such parts.
All fishes have teeth of the serrated form, with the single
exception of the fish known as the Scarus. In many of them there are
teeth even on the tongue and on the roof of the mouth. The reason
for this is that, living as they do in the water, they cannot but
allow this fluid to pass into the mouth with the food. The fluid
thus admitted they must necessarily discharge again without delay. For
were they not to do so, but to retain it for a time while
triturating the food, the water would run into their digestive
cavities. Their teeth therefore are all sharp, being adapted only
for cutting, and are numerous and set in many parts, that their
abundance may serve in lieu of any grinding faculty, to mince the food
into small bits. They are also curved, because these are almost the
only weapons which fishes possess.
In all these offices of the teeth the mouth also takes its part; but
besides these functions it is subservient to respiration, in all
such animals as breathe and are cooled by external agency. For nature,
as already said, uses the parts which are common to all animals for
many special purposes, and this of her own accord. Thus the mouth
has one universal function in all animals alike, namely its alimentary
office; but in some, besides this, the special duty of serving as a
weapon is attached to it; in others that of ministering to speech; and
again in many, though not in all, the office of respiration. All these
functions are thrown by nature upon one single organ, the construction
of which she varies so as to suit the variations of office.
Therefore it is that in some animals the mouth is contracted, while in
othe
rs it is of wide dimensions. The contracted form belongs to such
animals as use the mouth merely for nutritive, respiratory, and
vocal purposes; whereas in such as use it as a means of defence it has
a wide gape. This is its invariable form in such animals as are
saw-toothed. For seeing that their mode of warfare consists in biting,
it is advantageous to them that their mouth shall have a wide opening;
for the wider it opens, the greater will be the extent of the bite,
and the more numerous will be the teeth called into play.
What has just been said applies to fishes as well as to other
animals; and thus in such of them as are carnivorous, and made for
biting, the mouth has a wide gape; whereas in the rest it is small,
being placed at the extremity of a tapering snout. For this form is
suited for their purposes, while the other would be useless.
In birds the mouth consists of what is called the beak, which in
them is a substitute for lips and teeth. This beak presents variations
in harmony with the functions and protective purposes which it serves.
Thus in those birds that are called Crooked-clawed it is invariably
hooked, inasmuch as these birds are carnivorous, and eat no kind of
vegetable food whatsoever. For this form renders it serviceable to
them in obtaining the mastery over their prey, and is better suited
for deeds of violence than any other. Moreover, as their weapons of
offence consist of this beak and of their claws, these latter also are
more crooked in them than in the generality of birds. Similarly in
each other kind of bird the beak is suited to the mode of life.
Thus, in woodpeckers it is hard and strong, as also in crows and birds
of crowlike habit, while in the smaller birds it is delicate, so as to
be of use in collecting seeds and picking up minute animals. In such
birds, again, as eat herbage, and such as live about marshes-those,
for example, that swim and have webbed feet-the bill is broad, or
adapted in some other way to the mode of life. For a broad bill
enables a bird to dig into the ground with ease, just as, among
quadrupeds, does the broad snout of the pig, an animal which, like the
birds in question, lives on roots. Moreover, in these root-eating
birds and in some others of like habits of life, the tips of the
bill end in hard points, which gives them additional facility in
dealing with herbaceous food.
The several parts which are set on the head have now, pretty
nearly all, been considered. In man, however, the part which lies
between the head and the neck is called the face, this name,
(prosopon) being, it would seem, derived from the function of the
part. For as man is the only animal that stands erect, he is also
the only one that looks directly in front (proso) and the only one
whose voice is emitted in that direction.
2
We have now to treat of horns; for these also, when present, are
appendages of the head. They exist in none but viviparous animals;
though in some ovipara certain parts are metaphorically spoken of as
horns, in virtue of a certain resemblance. To none of such parts,
however, does the proper office of a horn belong; for they are never
used, as are the horns of vivipara, for purposes which require
strength, whether it be in self-protection or in offensive strife.
So also no polydactylous animal is furnished with horns. For horns are
defensive weapons, and these polydactylous animals possess other means
of security. For to some of them nature has given claws, to others
teeth suited for combat, and to the rest some other adequate defensive
appliance. There are horns, however, in most of the cloven-hoofed
animals, and in some of those that have a solid hoof, serving them
as an offensive weapon, and in some cases also as a defensive one.
There are horns also in all animals that have not been provided by
nature with some other means of security; such means, for instance, as
speed, which has been given to horses; or great size, as in camels;
for excessive bulk, such as has been given to these animals, and in
a still greater measure to elephants, is sufficient in itself to
protect an animal from being destroyed by others. Other animals
again are protected by the possession of tusks; and among these are
the swine, though they have a cloven hoof.
All animals again, whose horns are but useless appendages, have been
provided by nature with some additional means of security. Thus deer
are endowed with speed; for the large size and great branching of
their horns makes these a source of detriment rather than of profit to
their possessors. Similarly endowed are the Bubalus and gazelle; for
though these animals will stand up against some enemies and defend
themselves with their horns, yet they run away from such as are fierce
and pugnacious. The Bonasus again, whoe horns curve inwards towards
each other, is provided with a means of protection in the discharge of
its excrement; and of this it avails itself when frightened. There are
some other animals besides the Bonasus that have a similar mode of
defence. In no case, however, does nature ever give more than one
adequate means of protection to one and the same animal.
Most of the animals that have horns are cloven-hoofed; but the
Indian ass, as they call it, is also reported to be horned, though its
hoof is solid.
Again as the body, so far as regards its organs of motion,
consists of two distinct parts, the right and the left, so also and
for like reasons the horns of animals are, in the great majority of
cases, two in number. Still there are some that have but a single
horn; the Oryx, for instance, and the so-called Indian ass; in the
former of which the hoof is cloven, while in the latter it is solid.
In such animals the horn is set in the centre of the head; for as
the middle belongs equally to both extremes, this arrangement is the
one that comes nearest to each side having its own horn.
Again, it would appear consistent with reason that the single horn
should go with the solid rather than with the cloven hoof. For hoof,
whether solid or cloven, is of the same nature as horn; so that the
two naturally undergo division simultaneously and in the same animals.
Again, since the division of the cloven hoof depends on deficiency
of material, it is but rationally consistent, that nature, when she
gave an animal an excess of material for the hoofs, which thus
became solid, should have taken away something from the upper parts
and so made the animal to have but one horn. Rightly too did she act
when she chose the head whereon to set the horns; and AEsop's Momus is
beside the mark, when he finds fault with the bull for not having
its horns upon its shoulders. For from this position, says he, they
would have delivered their blow with the greatest force, whereas on
the head they occupy the weakest part of the whole body. Momus was but
dull-sighted in making this hostile criticism. For had the horns
been set on the shoulders, or had they been set on any other part than
/> they are, the encumbrance of their weight would have been increased,
not only without any compensating gain whatso::ver, but with the
disadvantage of impeding many bodily operations. For the point
whence the blows could be delivered with the greatest force was not
the only matter to be considered, but the point also whence they could
be delivered with the widest range. But as the bull has no hands and
cannot possibly have its horns on its feet or on its knees, where they
would prevent flexion, there remains no other site for them but the
head; and this therefore they necessarily occupy. In this position,
moreover, they are much less in the way of the movements of the body
than they would be elsewhere.
Deer are the only animals in which the horns are solid throughout,
and are also the only animals that cast them. This casting is not
simply advantageous to the deer from the increased lightness which
it produces, but, seeing how heavy the horns are, is a matter of
actual necessity.
In all other animals the horns are hollow for a certain distance,
and the end alone is solid, this being the part of use in a blow. At
the same time, to prevent even the hollow part from being weak, the
horn, though it grows out of the skin, has a solid piece from the
bones fitted into its cavity. For this arrangement is not only that
which makes the horns of the greatest service in fighting, but that
which causes them to be as little of an impediment as possible in
the other actions of life.
Such then are the reasons for which horns exist; and such the
reasons why they are present in some animals, absent from others.
Let us now consider the character of the material nature whose
necessary results have been made available by rational nature for a
final cause.
In the first place, then, the larger the bulk of animals, the
greater is the proportion of corporeal and earthy matter which they
contain. Thus no very small animal is known to have horns, the
smallest horned animal that we are acquainted with being the