2298. As the orifice begins to assume a male character, and the external parts to be more forcibly developed in the direction outwards, so, on the other hand, do the internal parts recede the more, and remain simply as ovaria or ovisacs, in which the ova, instead of being formed as such, dissolve into pollen, mucus, or male semen. These ovaria, which now secrete semen instead of vitelline vesicles, are called testes.
2299. The testes originate, while the mucous ova are being reduced to primary mucus, or to infusoria.
2300. What is male originates through an organic process of decomposition or putrefaction of the ova. The semen is an organic product of decomposition.
2301. The semen must contain infusoria. A semen which does not contain infusoria, is ovum-like, or feminine. Except at the time of heat or rut, and thus when the animals have a female character, the semen possesses no infusoria, and is in that case simply albumen.
2302. Semen, which is devoid of infusoria, is incapable of impregnation. How can one wretched female ovum impregnate or fructify another?
2303. As the trumpet-like tubes or oviducts belong to the ovaria, so are they developed with the testes, and now convey semen instead of ova. The female tubes become the vasa deferentia or spermatic ducts, the uterine cornua, the vesiculæ seminales.
2304. Between the vesiculæ seminales and the vagina or the penis the uterus shrivels up into the prostate gland, into which the vasa deferentia open, like the oviducts do into the uterus.
2305. As the matrix is the proper female organ, so will the spermatic ducts seek to combine with the penis, or at least open self-substantially upon the os uteri. The testes open either through the spermatic ducts into the vagina, as in Fishes, Reptiles, and Birds, or into the penis, as in the Gasteropods, Insects, and Mammalia.
2306. Male and female parts are therefore perfectly homologous, the former having a greater development of the external division, the latter of the internal.
2307. The female parts have undertaken the business of vegetation, or that of the viscera, the male that of the animal excitation.