Wherefore they have nor
spine, nor bone, nor sepia-bone, nor enveloping shell; but their body
by its hardness is its own protection and requires no extraneous
support. However, insects have a skin; but the skin is exceedingly
thin. These and such-like are the external organs of insects.
Internally, next after the mouth, comes a gut, in the majority of
cases straight and simple down to the outlet of the residuum: but in a
few cases the gut is coiled. No insect is provided with any viscera,
or is supplied with fat; and these statements apply to all animals
devoid of blood. Some have a stomach also, and attached to this the
rest of the gut, either simple or convoluted as in the case of the
acris or grasshopper.
The tettix or cicada, alone of such creatures (and, in fact, alone
of all creatures), is unprovided with a mouth, but it is provided with
the tongue-like formation found in insects furnished with frontward
stings; and this formation in the cicada is long, continuous, and
devoid of any split; and by the aid of this the creature feeds on dew,
and on dew only, and in its stomach no excretion is ever found. Of the
cicada there are several kinds, and they differ from one another in
relative magnitude, and in this respect that the achetes or chirper
is provided with a cleft or aperture under the hypozoma and has in
it a membrane quite discernible, whilst the membrane is indiscernible
in the tettigonia.
Furthermore, there are some strange creatures to be found in the
sea, which from their rarity we are unable to classify. Experienced
fishermen affirm, some that they have at times seen in the sea animals
like sticks, black, rounded, and of the same thickness throughout;
others that they have seen creatures resembling shields, red in
colour, and furnished with fins packed close together; and others that
they have seen creatures resembling the male organ in shape and size,
with a pair of fins in the place of the testicles, and they aver that
on one occasion a creature of this description was brought up on the
end of a nightline.
{BK4|CH7 ^paragraph 10}
So much then for the parts, external and internal, exceptional and
common, of all animals.
{BK4|CH8
8
-
We now proceed to treat of the senses; for there are diversities in
animals with regard to the senses, seeing that some animals have the
use of all the senses, and others the use of a limited number of them.
The total number of the senses (for we have no experience of any
special sense not here included), is five: sight, hearing, smell,
taste, and touch.
Man, then, and all vivipara that have feet, and, further, all
red-blooded ovipara, appear to have the use of all the five senses,
except where some isolated species has been subjected to mutilation,
as in the case of the mole. For this animal is deprived of sight; it
has no eyes visible, but if the skin- a thick one, by the way- be
stripped off the head, about the place in the exterior where eyes
usually are, the eyes are found inside in a stunted condition,
furnished with all the parts found in ordinary eyes; that is to say,
we find there the black rim, and the fatty part surrounding it; but
all these parts are smaller than the same parts in ordinary visible
eyes. There is no external sign of the existence of these organs in
the mole, owing to the thickness of the skin drawn over them, so that
it would seem that the natural course of development were congenitally
arrested; [for extending from the brain at its junction with the
marrow are two strong sinewy ducts running past the sockets of the
eyes, and terminating at the upper eye-teeth]. All the other animals
of the kinds above mentioned have a perception of colour and of sound,
and the senses of smell and taste; the fifth sense, that, namely, of
touch, is common to all animals whatsoever.
In some animals the organs of sense are plainly discernible; and
this is especially the case with the eyes. For animals have a special
locality for the eyes, and also a special locality for hearing: that
is to say, some animals have ears, while others have the passage for
sound discernible. It is the same with the sense of smell; that is to
say, some animals have nostrils, and others have only the passages for
smell, such as birds. It is the same also with the organ of taste, the
tongue. Of aquatic red-blooded animals, fishes possess the organ of
taste, namely the tongue, but it is in an imperfect and amorphous
form, in other words it is osseous and undetached. In some fish the
palate is fleshy, as in the fresh-water carp, so that by an
inattentive observer it might be mistaken for a tongue.
There is no doubt but that fishes have the sense of taste, for a
great number of them delight in special flavours; and fishes freely
take the hook if it be baited with a piece of flesh from a tunny or
from any fat fish, obviously enjoying the taste and the eating of food
of this kind. Fishes have no visible organs for hearing or for smell;
for what might appear to indicate an organ for smell in the region of
the nostril has no communication with the brain. These indications, in
fact, in some cases lead nowhere, like blind alleys, and in other
cases lead only to the gills; but for all this fishes undoubtedly hear
and smell. For they are observed to run away from any loud noise, such
as would be made by the rowing of a galley, so as to become easy of
capture in their holes; for, by the way, though a sound be very slight
in the open air, it has a loud and alarming resonance to creatures
that hear under water. And this is shown in the capture of the