the egg, (for nothing is its own author,) and that the said vital principle (anima) passes from the egg into the punctum saliens, presently into the heart, and thence into the chick.
Moreover, if the egg have a prolific virtue, and a vegetative soul, by which the chick is constructed, and if it owe them, as is allowed on all hands, to the semen of the cock; it is clear that this semen is also endowed with an active princi- ple (anima.) For such is Aristotle's opinion, when he ex- presses himself as follows : " As to whether the semen has a vital principle (anima) or not, the same reasoning must be adduced which we have employed in the consideration of other parts. For no active principle (anima) can exist, except in that thing whose vital principle it is ; nor can there be any part which is not partaker of the vital principle, except it be equivocally, as the eye of a dead man. We must, therefore, allow, both that the semen has an active principle (anima) and is potential."
Now from these premises, it follows that the male is the primary efficient in which the ratio and forma reside, which produces a seed or rather a prolific geniture, and imparts it, imbued as it is with an anima vegetativa (with which also the rest of its parts are endowed) to the female. The introduction of this geniture begets such a movement in the material of the hen, that the production of an animate egg is the result, and from thence too the first particle of the chick is animated, and afterwards the whole chick. And so, according to Aris- totle, either the same soul passes, by means of some metem- psychosis, from the cock into his geniture, from the geniture into the material of the female, thence into the egg, and from the egg into the chick; or else, it is raised up in each of the subsequent things by its respective antecedent ; namely, in the seed of the male by the male himself, in the egg by the seed, last in the chick by the egg, as light is derived from light.
The efficient, therefore, which we look for in the egg, to explain the birth of the chick, is the vital principle (anima) ; and there- fore, the vital principle of the egg ; for, according to Aristotle, a soul does not exist except in that thing whose soul it is.
But it is manifest, that the seed of the male is not the efficient of the chick ; neither as an instrument capable of forming the chick by its motion, as Aristotle would have it,
