All sanguineous animals eject sperm. As to what, and how, it
contributes to generation, these questions will be discussed in
another treatise. Taking the size of his body into account, man
emits more sperm than any other animal. In hairy-coated animals the
sperm is sticky, but in other animals it is not so. It is white in all
cases, and Herodotus is under a misapprehension when he states that
the Aethiopians eject black sperm.

Sperm issues from the body white and consistent, if it be healthy,
and after quitting the body becomes thin and black. In frosty
weather it does not coagulate, but gets exceedingly thin and watery
both in colour and consistency; but it coagulates and thickens under
the influence of heat. If it be long in the womb before issuing out,
it comes more than usually thick; and sometimes it comes out dry and
compact. Sperm capable of impregnating or of fructification sinks in
water; sperm incapable Of producing that result dissolves away. But
there is no truth in what Ctesias has written about the sperm of the
elephant.