2308. Since the male parts are no new formation, but the female parts themselves, only characterized by internal arrest, and external increase of development, so do male and female parts appear incapable of occurring together in any animal. Perfect hermaphrodites would, accordingly, be impossible; for where testes are, no ovaria could be, because the testes are themselves the ovaria, or the latter only changed.
2309. Hence androgynism would be possible only by one ovarium remaining as such, and the other being converted into a testis.
2310. This development appears only possible when the two halves of the body are unequal. Asymmetrical animals only can be androgynous. In the snails one of the two molluscan shell-valves has been more largely developed than the other, and therefore one half also of the body is greater than the other. On this account many hermaphrodites are found among these animals.
2311. Thus, there ought to be no androgynous animals with at the same time two ovaria and two testes. Nevertheless, this very peculiarity occurs in many of the lower organized animals, e. g. the worms.
2312. Accordingly, the principle of androgynism is in general to be found in the want of symmetry. Symmetrical animals are as a rule diœcious. No hermaphrodite is found among the Insects, Fishes, Reptiles, Birds, and Mammalia.
2313. If such occur, they are formations that have remained persistent at the lower stage of development, or upon the transition of the embryo through the Snail-type of organization; they are thus monstrosities, or malformations.
2314. These malformations also, when occurring in the higher animals, can never possess more than one testicle and one ovarium. The uterus then ranks midway between its condition as such, and that of a prostate gland; the spermatic tube or urethra opens after a female fashion below the root of the penis.
Impregnation.
2315. Since the male sex is related to the female, as corolla to capsule, as leaf to stalk, as air to water, and as light to matter; so is it related also as integument to intestine, as lung to lymphatic vessel, as artery to vein, as nerve to flesh or muscle, as Animal to Vegetative.