species, but in so far as this man and that woman in these bones and muscles constitute human forms, of both of which, if So- crates be a certain mixture, a compound of both, that by which he is made must needs be a mixed univocal compound of the two ; i. e. a mixed efficient of a mixed effect. And therefore it is that the male and female by themselves, and separately, are not genetic, but become so united in coitu, and made one animal as it were; whence, from the two as one, is produced and educed that which is the true efficient proximate cause of conception.
The medical writers also, in directing their attention to the particulars of human generation alone, come to conclusions on generation at large; and the spermatic fluid proceeding from the parents in coitu has in all probability been taken by them for true seed, analogous to the seeds of plants. It is not without reason, therefore, that they imagine the mixed efficient cause of the future offspring to be constituted by a mixture of the seminal matters of each parent. And then they go on to assert that the mixture proceeding immediately from intercourse is de- posited in the uterus and forms the rudiments of the conception. That things are very different, however, is made manifest by our preceding history of the egg, which is a true conception.
EXERCISE THE THIRTY-FOURTH.
Of the matter of the egg, in opposition to the Aristotelians and the medical writers.
The position taken up by the medical writers against the Aristotelians, viz., that the blood is not the first element in a con- ception, is clearly shown from the generation of the egg to be well chosen : neither during intercourse, nor before nor after it, is there a drop of blood contained in the uterus of the fowl; nei- ther are the rudiments of eggs red, but white. Many animals also conceive in whose uteri, if they be suddenly laid open after intercourse, no blood can be demonstrated.
But when they contend that the maternal blood is the food of the foetus in utero, especially of its more sanguineous parts,
