rudiments of all eggs are produced in the ovary and take their increase, seems to be the very same from which all the other parts of the hen, namely, the fleshy, nervous, and bony struc- tures, as well as the head and the rest of the members, are nourished and grow. Nourishment is in fact conveyed to each single papula and yelk contained in the ovary by means of vessels, in the same way precisely as to all the other parts of the hen. But the place where the egg is provided with mem- branes, and perfected by the addition of the chalazse and shell, is the uterus.
But that the hen neither emits any semen during inter- course, nor sheds any blood into the cavity of the uterus, and that the egg is not formed in the mode in which Aristotle sup- posed a conception to arise, nor, as physicians imagine, from a mixture of the seminal fluids; as also that the semen of the cock does not penetrate into, nor is attracted towards, the cavity of the uterus of the hen, is all made manifestly clear by this one observation, namely, that after intercourse there is nothing more to be found in the uterus, than there was before the act. And when this shall have been afterwards clearly established and demonstrated to be true of all kinds of animals, which conceive in a uterus, it will at the same time be equally evi- dent, that what has hitherto been handed down to us from all antiquity on the generation of animals, is erroneous ; that the foetus is not constituted of the semen either of the male or female, nor of a mixture of the two, nor of the menstrual blood, but that in all animals, as well in the prolific conception as after it, the same series of phenomena occur as in the genera- tion of the chick from the egg, and as in the production of plants from the seeds of their several kinds. For, besides that, it appears the male is not required as being in himself agent, workman, and efficient cause ; nor the female, as if she supplied the matter ; but that each, male as well as female, may be said to be in some sort the operative and parent ; and the foetus, as a mixture of both, is created a mixed resemblance and kind. Nor is that true which Aristotle often affirms, and physicians take for granted, namely, that immediately after intercourse, something either of the foetus or the conception may be found in the uterus, (for instance, the heart, the " three bullse," or some other principal part,) at any rate something
