History of Animals
in amount: and the hooves or claws get larger in size; and the same is
the case with the beaks of birds. The claws also increase in size,
as do also the nails.
With regard to winged animals, such as birds, no creature is
liable to change of colour by reason of age, excepting the crane.
The wings of this bird are ash-coloured at first, but as it grows
old the wings get black. Again, owing to special climatic
influences, as when unusual frost prevails, a change is sometimes
observed to take place in birds whose plumage is of one uniform
colour; thus, birds that have dusky or downright black plumage turn
white or grey, as the raven, the sparrow, and the swallow; but no case
has ever yet been known of a change of colour from white to black.
(Further, most birds change the colour of their plumage at different
seasons of the year, so much so that a man ignorant of their habits
might be mistaken as to their identity.) Some animals change the
colour of their hair with a change in their drinking-water, for in
some countries the same species of animal is found white in one
district and black in another. And in regard to the commerce of the
sexes, water in many places is of such peculiar quality that rams,
if they have intercourse with the female after drinking it, beget
black lambs, as is the case with the water of the Psychrus
(so-called from its coldness), a river in the district of Assyritis in
the Chalcidic Peninsula, on the coast of Thrace; and in Antandria
there are two rivers of which one makes the lambs white and the
other black. The river Scamander also has the reputation of making
lambs yellow, and that is the reason, they say, why Homer designates
it the 'Yellow River.' Animals as a general rule have no hair on their
internal surfaces, and, in regard to their extremities, they have hair
on the upper, but not on the lower side.
The hare, or dasypod, is the only animal known to have hair inside
its mouth and underneath its feet. Further, the so-called mousewhale
instead of teeth has hairs in its mouth resembling pigs' bristles.
Hairs after being cut grow at the bottom but not at the top; if
feathers be cut off, they grow neither at top nor bottom, but shed and
fall out. Further, the bee's wing will not grow again after being
plucked off, nor will the wing of any creature that has undivided
wings. Neither will the sting grow again if the bee lose it, but the
creature will die of the loss.
In all sanguineous animals membranes are found. And membrane
resembles a thin close-textured skin, but its qualities are different,
as it admits neither of cleavage nor of extension. Membrane envelops
each one of the bones and each one of the viscera, both in the
larger and the smaller animals; though in the smaller animals the
membranes are indiscernible from their extreme tenuity and minuteness.
The largest of all the membranes are the two that surround the
brain, and of these two the one that lines the bony skull is
stronger and thicker than the one that envelops the brain; next in
order of magnitude comes the membrane that encloses the heart. If
membrane be bared and cut asunder it will not grow together again, and
the bone thus stripped of its membrane mortifies.
The omentum or caul, by the way, is membrane. All sanguineous
animals are furnished with this organ; but in some animals the organ
is supplied with fat, and in others it is devoid of it. The omentum
has both its starting-point and its attachment, with ambidental
vivipara, in the centre of the stomach, where the stomach has a kind
of suture; in non-ambidental vivipara it has its starting-point and
attachment in the chief of the ruminating stomachs.