INTRODUCTION.
It will not, I trust, be unwelcome to you, candid reader, if I yield to the wishes, I might even say the entreaties, of many, and in these Exercises on Animal Generation, lay before the student and lover of truth what I have observed on this subject from anatomical dissections, which turns out to be very different from anything that is delivered by authors, whether philosophers or physicians.
Physicians, following Galen, teach that from the semen of the male and female mingled in coition the offspring is produced, and resembles one or other, according to the predominance of this one or of that; and farther, that in virtue of the same predominance, it is either male or female. Sometimes they declare the semen masculinum as the efficient cause, and the semen femininum as supplying the matter; and sometimes, again, they advocate precisely the opposite doctrine. Aristotle, one of Nature's most diligent inquirers, however affirms the principles of generation to be the male and the female, she contributing the matter, he the form; and that immediately after the sexual act the vital principle and the first particle of the future foetus, viz. the heart, in animals that have red blood, are formed from the menstrual blood in the uterus.
But that these are erroneous and hasty conclusions is easily made to appear: like phantoms of darkness they suddenly vanish before the light of anatomical inquiry. Nor is any long
