Page:The Works of William Harvey (part 1 of 2).djvu/416

 Aristotle's opinion, as well as the seeds of plants, has a vegeta- tive soul,) that soul, or at all events the vegetative one, must be communicated as a graft, and transferred from the male to the female, from the female to the egg, from the egg to the foetus ; or else be generated in each of these successively by the con- tagion of coition.

The subject, nevertheless, seems full of ambiguity; and so Aristotle, although he allows that the semen of the male has such great virtue, that a single emission of it suffices for fecun- dating very many eggs at the same time, yet, lest this admis- sion should seem to gainsay the efficacy of frequent repetitions of intercourse, he further says, 1 " In birds, not even those eggs which arise through intercourse can greatly increase in size, unless the intercourse be continued ; and the reason of this is, that, as in women, the menstrual excretion is drawn downwards by sexual intercourse, (for the uterus, becoming warm, attracts moisture, and its pores are opened,) so also does it happen with birds, in which the menstrual excrement, because it accumu- lates gradually, and is retained above the cincture, and cannot escape, from being in small quantity, only passes off when it has reached the uterus itself. For by this is the egg increased, as is the foetus of the viviparous animal by that which flows through the umbilicus. For almost all birds, after but a single act of intercourse, continue to produce eggs, but they are small."

Now, so far perhaps would the opinion of Aristotle be cor- rect, that more and larger eggs are procured by frequently- repeated intercourse ; because, as he says, there may be " a flow of more fruitful material to the womb, when warmed by the heat of coition ;" not however that frequent coition must neces- sarily take place in order to render the eggs that are laid prolific. For experience, as we have said, teaches the contrary, and the reason which he alleges does not seem convincing; since the rudiments of eggs are not formed in the uterus from menstrual blood, which is found in no part of the hen, but in the ovary, where no blood pre-exists, and originate as well without, as along with the intercourse of the cock.

The hen, as well as all other females, supplies matter, nutri- tion, and place to the conception. The matter, whence the

' De Gen. Aoim. lib. iii, cap. 1.