Hippo, that the more compacted and strong sperm, and the more fluid and weak, discriminate the sexes.

Anaxagoras and Parmenides, that the seed of the man is naturally cast from his right side into the right side of the womb, or from the left side of the man into the left side of the womb; there is an alteration in this course of nature when females are generated.
Cleophanes, whom Aristotle makes mention of, assigns the generation of men to the right testicle, of women to the left.

Leucippus gives the reason of it to the alteration or diversity of parts, according to which the man hath a yard, the female the matrix; as to any other reason he is silent.

Democritus, that the parts common to both sexes are engendered indifferently; but the peculiar parts by the one that is more powerful.
Hippo, that if the spermatic faculty be more effectual, the male, if the nutritive aliment, the female is generated..