a fact which Aldrovandus was either ignorant of or concealed. Fabricius admits this fact ; but though he has denied that the semen of the male penetrates to the uterus or is ever found in the egg, he nevertheless, contends, that the chalazse alone of all the parts of the egg are impregnated with the prolific power of the egg, and are the repositories of the fecundating influence ; and this, with the fact staring him in the face all the while, that there is no perceptible difference between the chalazse of a prolific and an unprolific egg. And when he admits, that the mere rudiments of eggs in the ovary, as well as the vitelli that are surrounded with albumen, become fecundated through the intercourse of the cock, I conceive that this must have been the cause of the error committed by so distinguished an individual. It was the current opinion, as I have said oftener than once, both among philosophers and physicians, that the matter of the embryo in animal generation, was the geniture, either of the male, or of the female, or resulted from a mixture of the two, and that from this, deposited in the uterus, like a seed in the ground, which produces a plant, the animal was engendered. Aristotle, himself, is not very far from the same view, when he maintains the menstrual blood of the female to be the seed, which the semen of the male coagulates, and so composes the conception.
The error which we have announced, having been admitted by all in former times, as a matter of certainty, it it not to be wondered at, that various erroneous opinions based on each man's conjecture, should have emanated from it. They, how- ever, are wholly mistaken, who fancy that anything in the shape of a ' prepared or fit matter ' must necessarily remain in the uterus after intercourse, from which the foetus is pro- duced, or the first conception is formed, or that anything is immediately fashioned in the uterine cavity that corresponds to the seed of a plant deposited in the bosom of the ground. For it is quite certain, that in the uterus of the fowl, and the same thing is true of the uterus of every other female animal, there is nothing discoverable after intercourse more than there was before it.
It appears, consequently, that Fabricius erred when he said : * "In the same way as a viviparous animal is incorpo-
1 Op. sup. cit. p. 35.
