introduction of a vital principle or soul into the semen or " geniture," can the aforementioned doctrine be defended.
And hence have arisen all the controversies and problems concerning the attraction of the magnet and of amber; on sympathy and antipathy; on poisons and the contagion of pestilential diseases; on alexipharmics and medicines which prove curative or injurious through some hidden or rather un- known property, all of which seem to come into play indepen- dently of contact. And above all on what it is in generation which, in virtue of a momentary contact nay, not even of contact, save through several media forms the parts of the chick from the egg by epigenesis in a certain order, and pro- duces an " univocal" and like itself, and that entirely because it was in contact at a former period. How, I ask again, does that which is not present, and which only enjoyed extrinsic contact, come to constitute and order all the members of the chick in the egg exposed without the body of the parent, and often at a long interval after it is laid ? how does it confer life or soul, and a species compounded of those of the concurring generants? Inasmuch as nothing, it seems, can reproduce itself in another's likeness.
EXERCISE THE FIFTIETH.
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Of the efficient cause of animals, and its conditions.
That we may proceed in our subject, therefore, and pene- trate so far into the knowledge of the efficient cause of animal generation as seems needful in this place, we must begin by observing what instruments or media are devoted to it. And here we come at once to the distinction into male and female ; seminal fluid and ovum, and its primordium. For some males, as well as some females, are barren, or but little prolific; and the seed of the male is at one time more, at another time less prolific ; because the semen masculinum stored up in the vesiculse seminales is esteemed unfruitful, unless it is raised
