one time " the genital and foetific fluid/' at another, " the vital virus/' For he says 1 : " The male fish sprinkles the ova with his genital semen, and from the ova that are touched by this vital virus young fishes are engendered."
Let it then be admitted as matter of certainty that the em- bryo is produced by contagion. But a great difficulty imme- diately arises, when we ask : how, in what way is this contagion the author of so great a work ? By what condition do parents through it engender offspring like themselves, or how does the semen masculinum produce an " univocal" like the male whence it flowed ? When it disappears after the contact, and is neught in act ulteriorly, either by virtue of contact or presence, but is corrupt and has become a nonentity, how, I ask, does a non- entity act ? How does a thing which is not in contact fashion another thing like itself? How does a thing which is dead it- self impart life to something else, and that only because at a former period it was in contact ?
For the reasoning of Aristotle 2 appears to be false, or at all events defective, where he contends " That generation cannot take place without an active and a passive principle; and that those things can neither act nor prove passive which do not touch ; but that those things come into mutual contact which, whilst they are of different sizes, and are in different places, have their extremes together."
But when it clearly appears that contagion from noncontin- gents, and things not having their extremities together, pro- duce ill effects on animals, wherefore should not the same law avail in respect of their life and generation? There is an " efficient" in the egg which, by its plastic virtue (for the male has only touched though he no longer touches, nor are there any extremes together), produces and fashions the foetus in its kind and likeness. And through so many media or instru- ments is this power, the agent of fecundity, transmitted or required that neither by any movement of instruments as in works of art, nor by the instance of the automaton quoted by Aristotle, nor of our clocks, nor of the kingdom in which the mandate of the sovereign is everywhere of avail, nor yet by the
1 Hist. Animal, lib. vi, cap. 13. * De Gen. et cor. lib. i, cap. 6.
