the back than on the under side of the body; whereas in man the
contrary is the case, and the hair is more abundant on the front
surface than on the back. The reason for this is that hair is intended
to serve as a protection to its possessor. Now, in quadrupeds, owing
to their inclined attitude, the under or anterior surface does not
require so much protection as the back, and is therefore left
comparatively bald, in spite of its being the nobler of the two sides.
But in man, owing to his upright attitude, the anterior and
posterior surfaces of the body are on an equality as regards need of
protection. Nature therefore has assigned the protective covering to
the nobler of the two surfaces; for invariably she brings about the
best arrangement of such as are possible. This then is the reason that
there is no lower eyelash in any quadruped; though in some a few
scattered hairs sprout out under the lower lid. This also is the
reason that they never have hair in the axillae, nor on the pubes,
as man has. Their hair, then, instead of being collected in these
parts, is either thickly set over the whole dorsal surface, as is
the case for instance in dogs, or, sometimes, forms a mane, as in
horses and the like, or as in the male lion where the mane is still
more flowing and ample. So, again, whenever there is a tail of any
length, nature decks it with hair, with long hair if the stem of the
tail be short, as in horses, with short hair if the stem be long,
regard also being had to the condition of the rest of the body. For
nature invariably gives to one part what she subtracts from another.
Thus when she has covered the general surface of an animal's body with
an excess of hair, she leaves a deficiency in the region of the
tail. This, for instance, in the case with bears.
No animal has so much hair on the head as man. This, in the first
place, is the necessary result of the fluid character of his brain,
and of the presence of so many sutures in his skull. For wherever
there is the most fluid and the most heat, there also must necessarily
occur the greatest outgrowth. But, secondly, the thickness of the hair
in this part has a final cause, being intended to protect the head, by
preserving it from excess of either heat or cold. And as the brain
of man is larger and more fluid than that of any other animal, it
requires a proportionately greater amount of protection. For the
more fluid a substance is, the more readily does it get excessively
heated or excessively chilled, while substances of an opposite
character are less liable to such injurious affections.
These, however, are matters which by their close connexion with
eyelashes have led us to digress from our real topic, namely the cause
to which these lashes owe their existence. We must therefore defer any
further remarks we may have to make on these matters till the proper
occasion arises and then return to their consideration.
15
Both eyebrows and eyelashes exist for the protection of the eyes;
the former that they may shelter them, like the eaves of a house, from
any fluids that trickle down from the head; the latter to act like the
palisades which are sometimes placed in front of enclosures, and
keep out any objects which might otherwise get in. The brows are
placed over the junction of two bones, which is the reason that in old
age they often become so bushy as to require cutting. The lashes are
set at the terminations of small blood-vessels. For the vessels come
to an end where the skin itself terminates; and, in all places where
these endings occur, the exudation of moisture of a corporeal
character necessitates the growth of hairs, unless there be some
operation of nature which interferes, by diverting the moisture to
another purpose.
16
Viviparous quadrupeds, as a rule, present no great variety of form
in the organ of smell. In those of them, however, whose jaws project
forwards and taper to a narrow end, so as to form what is called a
snout, the nostrils are placed in this projection, there being no
other available plan; while, in the rest, there is a more definite
demarcation between nostrils and jaws. But in no animal is this part
so peculiar as in the elephant, where it attains an extraordinary
and strength. For the elephant uses its nostril as a hand; this
being the instrument with which it conveys food, fluid and solid
alike, to its mouth. With it, too, it tears up trees, coiling it round
their stems. In fact it applies it generally to the purposes of a
hand. For the elephant has the double character of a land animal,
and of one that lives in swamps. Seeing then that it has to get its
food from the water, and yet must necessarily breathe, inasmuch as
it is a land animal and has blood; seeing, also, that its excessive
weight prevents it from passing rapidly from water to land, as some
other sanguineous vivipara that breathe can do, it becomes necessary
that it shall be suited alike for life in the water and for life on
dry land. just then as divers are sometimes provided with
instruments for respiration, through which they can draw air from
above the water, and thus may remain for a long time under the sea, so
also have elephants been furnished by nature with their lengthened
nostril; and, whenever they have to traverse the water, they lift this
up above the surface and breathe through it. For the elephant's
proboscis, as already said, is a nostril. Now it would have been
impossible for this nostril to have the form of a proboscis, had it
been hard and incapable of bending. For its very length would then
have prevented the animal from supplying itself with food, being as
great an impediment as the of certain oxen, that are said to be
obliged to walk backwards while they are grazing. It is therefore soft
and flexible, and, being such, is made, in addition to its own
proper functions, to serve the office of the fore-feet; nature in this
following her wonted plan of using one and the same part for several
purposes. For in polydactylous quadrupeds the fore-feet are intended
not merely to support the weight of the body, but to serve as hands.
But in elephants, though they must be reckoned polydactylous, as their
foot has neither cloven nor solid hoof, the fore-feet, owing to the
great size and weight of the body, are reduced to the condition of
mere supports; and indeed their slow motion and unfitness for
bending make them useless for any other purpose. A nostril, then, is
given to the elephant for respiration, as to every other animal that
has a lung, and is lengthened out and endowed with its power of
coiling because the animal has to remain for considerable periods of
time in the water, and is unable to pass thence to dry ground with any
rapidity. But as the feet are shorn of their full office, this same
part is also, as already said, made by nature to supply their place,
and give such help as otherwise would be rendered by them.
As to other sanguineous animals, the Birds, the Serpe
nts, and the
Oviparous quadrupeds, in all of them there are the nostril-holes,
placed in front of the mouth; but in none are there any distinctly
formed nostrils, nothing in fact which can be called nostrils except
from a functional point of view. A bird at any rate has nothing
which can properly be called a nose. For its so-called beak is a
substitute for jaws. The reason for this is to be found in the natural
conformation of birds. For they are winged bipeds; and this makes it
necessary that their heads and neck shall be of light weight; just
as it makes it necessary that their breast shall be narrow. The beak
therefore with which they are provided is formed of a bone-like
substance, in order that it may serve as a weapon as well as for
nutritive purposes, but is made of narrow dimensions to suit the small
size of the head. In this beak are placed the olfactory passages.
But there are no nostrils; for such could not possibly be placed
there.
As for those animals that have no respiration, it has already been
explained why it is that they are without nostrils, and perceive
odours either through gills, or through a blowhole, or, if they are
insects, by the hypozoma; and how the power of smelling depends,
like their motion, upon the innate spirit of their bodies, which in
all of them is implanted by nature and not introduced from without.
Under the nostrils are the lips, in such sanguineous animals, that
is, as have teeth. For in birds, as already has been said, the
purposes of nutrition and defence are fulfilled by a bonelike beak,
which forms a compound substitute for teeth and lips. For supposing
that one were to cut off a man's lips, unite his upper teeth together,
and similarly his under ones, and then were to lengthen out the two
separate pieces thus formed, narrowing them on either side and
making them project forwards, supposing, I say, this to be done, we
should at once have a bird-like beak.
The use of the lips in all animals except man is to preserve and
guard the teeth; and thus it is that the distinctness with which the
lips are formed is in direct proportion to the degree of nicety and
perfection with which the teeth are fashioned. In man the lips are
soft and flesh-like and capable of separating from each other. Their
purpose, as in other animals, is to guard the teeth, but they are more
especially intended to serve a higher office, contributing in common
with other parts to man's faculty of speech. For just as nature has
made man's tongue unlike that of other animals, and, in accordance
with what I have said is her not uncommon practice, has used it for
two distinct operations, namely for the perception of savours and
for speech, so also has she acted with regard to the lips, and made
them serve both for speech and for the protection of the teeth. For
vocal speech consists of combinations of the letters, and most of
these would be impossible to pronounce, were the lips not moist, nor
the tongue such as it is. For some letters are formed by closures of
the lips and others by applications of the tongue. But what are the
differences presented by these and what the nature and extent of
such differences, are questions to which answers must be sought from
those who are versed in metrical science. It was necessary that the
two parts which we are discussing should, in conformity with the
requirements, be severally adapted to fulfil the office mentioned
above, and be of appropriate character. Therefore are they made of
flesh, and flesh is softer in man than in any other animal, the reason
for this being that of all animals man has the most delicate sense
of touch.
17
The tongue is placed under the vaulted roof of the mouth. In land
animals it presents but little diversity. But in other animals it is
variable, and this whethe+r we compare them as a class with such as
live on land, or compare their several species with each other. It
is in man that the tongue attains its greatest degree of freedom, of
softness, and of breadth; the object of this being to render it
suitable for its double function. For its softness fits it for the
perception of savours, a sense which is more delicate in man than in
any other animal, softness being most impressionable by touch, of
which sense taste is but a variety. This same softness again, together
with its breadth, adapts it for the articulation of letters and for
speech. For these qualities, combined with its freedom from
attachment, are those which suit it best for advancing and retiring in
every direction. That this is so is plain, if we consider the case
of those who are tongue-tied in however slight a degree. For their
speech is indistinct and lisping; that is to say there are certain
letters which they cannot pronounce. In being broad is comprised the
possibility of becoming narrow; for in the great the small is
included, but not the great in the small.
What has been said explains why, among birds, those that are most
capable of pronouncing letters are such as have the broadest
tongues; and why the viviparous and sanguineous quadrupeds, where
the tongue is hard and thick and not free in its motions, have a
very limited vocal articulation. Some birds have a considerable
variety of notes. These are the smaller kinds. But it is the birds
with talons that have the broader tongues. All birds use their tongues
to communicate with each other. But some do this in a greater degree
than the rest; so that in some cases it even seems as though actual
instruction were imparted from one to another by its agency. These,
however, are matters which have already been discussed in the
Researches concerning Animals.
As to those oviparous and sanguineous animals that live not in the
air but on the earth, their tongue in most cases is tied down and
hard, and is therefore useless for vocal purposes; in the serpents,
however, and in the lizards it is long and forked, so as to be
suited for the perception of savours. So long indeed is this part in
serpents, that though small while in the mouth it can be protruded
to a great distance. In these animals it is forked and has a fine
and hair-like extremity, because of their great liking for dainty
food. For by this arrangement they derive a twofold pleasure from
savours, their gustatory sensation being as it were doubled.
Even some bloodless animals have an organ that serves for the
perception of savours; and in sanguineous animals such an organ is
invariably variably For even in such of these as would seem to an
ordinary observer to have nothing of the kind, some of the fishes
for example, there is a kind of shabby representative of a tongue,
much like what exists in river crocodiles. In most of these cases
the apparent absence of the part can be rationally explained on some
ground or other. For in the first place the interior of the mouth in
animals of this character is invariably spinous. Secondly, in water
animals there is but short space of time fo
r the perception of
savours, and as the use of this sense is thus of short duration,
shortened also is the separate part which subserves it. The reason for
their food being so rapidly transmitted to the stomach is that they
cannot possibly spend any time in sucking out the juices; for were
they to attempt to do so, the water would make its way in during the
process. Unless therefore one pulls their mouth very widely open,
the projection of this part is quite invisible. The region exposed
by thus opening the mouth is spinous; for it is formed by the close
apposition of the gills, which are of a spinous character.
In crocodiles the immobility of the lower jaw also contributes in
some measure to stunt the development of the tongue. For the
crocodile's tongue is adherent to the lower jaw. For its upper and
lower jaws are, as it were, inverted, it being the upper jaw which
in other animals is the immovable one. The tongue, however, on this
animal is not attached to the upper jaw, because that would
interfere with the ingestion of food, but adheres to the lower jaw,
because this is, as it were, the upper one which has changed its
place. Moreover, it is the crocodile's lot, though a land animal, to
live the life of a fish, and this again necessarily involves an
indistinct formation of the part in question.
The roof of the mouth resembles flesh, even in many of the fishes;
and in some of the river species, as for instance in the fishes
known as Cyprini, is so very flesh-like and soft as to be taken by
careless observers for a tongue. The tongue of fishes, however, though
it exists as a separate part, is never formed with such distinctness
as this, as has been already explained. Again, as the gustatory
sensibility is intended to serve animals in the selection of food,
it is not diffused equally over the whole surface of the tongue-like
organ, but is placed chiefly in the tip; and for this reason it is the
tip which is the only part of the tongue separated in fishes from
the rest of the mouth. As all animals are sensible to the pleasure
derivable from food, they all feel a desire for it. For the object