Chapter XVII.

1. All sanguineous animals eject the spermatic fluid; the office it performs in generation, and how it is performed, will be treated of in another place. In proportion to his size man ejects more than other animals. This fluid, in animals covered with hair, is glutinous, in others it is not glutinous; in all it is white, so that Herodotus is mistaken when he says that the Ethiopians have black semen.[98] The semen comes out white and thick if it is healthy, but after ejection it becomes thin and black; it does not thicken with cold, but becomes thin and watery, both in colour and density. By heat it coagulates and thickens, and when it has been ejected for any time into the uterus, it comes out more thick, and sometimes dry and twisted together. That which is fruitful sinks in water, but the barren mixes with it. All that Ctesias said about the semen of the elephant is false.