ON GENERATION. 28.9
that correspond in their seasons of heat and times of uterogesta- tion, and do not differ greatly in their size,) produce their first younglike themselves, but partaking of the speciesof both parents; of this description is the progeny of the fox and dog, of the par- tridge and common fowl, &c.; but in the course of time from diversity results diversity, and the progeny of these different parents at length acquires the form of the female ; in the same way as foreign seed is changed at last in conformity with the nature of the soil, which supplies matter and body to the seed."
From this it appears, that in the generation of the partridge with the common fowl it is not the male alone that is efficient, but the female also ; inasmuch as it is not the male form only, but one common or subordinate that appears in the hybrid, as like the female as it is like the male in vital endowment (anima), and bodily form. But the vital endowment (anima) is that which is the true form and species of an animal.
Farther, the female seems even to have a superior claim to be considered the efficient cause: "In the course of time," says the philosopher, " the progeny of different species assumes the form of the female ;" as if the semen or influence of the male were the less powerful; as if the species impressed by him disappeared with the lapse of time, and were expelled by a more powerful efficient cause. And the instance from the soil confirms this still farther : " for foreign seeds are changed at length according to the nature of the soil." Whence it seems probable that the female is actually of more moment in generation than the male; for, " in the world at large it is admitted that the earth is to nature as the female or mother, whilst climate, the sun, and other things of the same description, are spoken of by the names of generator and father." 1 The earth, too, spontaneously en- genders many things without seed ; and among animals, certain females, but females only, procreate of themselves and without the concurrence of the male : hens, for example, lay hypenemic eggs ; but males, without the intervention of females, engender nothing.
By the same arguments, indeed, by which the male is main- tained to be the principle and prime ' efficient ' in generation, it would seem that the female might be confirmed in the preroga-
Op. cit. lib. i, cap. 2.
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