(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.