ON GENERATION. 427 



of twofold nature to the egg, and a twofold egg in this kind, 

 so does he assert a twofold action and a twofold animal engen- 

 dered. For," he proceeds, "from the first eggs, which are the 

 primordia of generation, a worm is constantly produced ; viz. : 

 from the eggs of flies, ants, bees, silkworms, &c., in which some 

 fluid is contained, and from the whole of which fluid the 

 worm is engendered ; but from the second eggs, formed by the 

 worms themselves, butterflies are engendered and disclosed, viz. : 

 flying animals contained in a shell, or follicle, or egg, which 

 shell giving way the winged creature escapes; precisely as 

 Aristotle 1 has it where he speaks of the egg of the locust." 

 Finally, whilst the higher animals produced from eggs are per- 

 fected by a succession of parts, the lower creatures that arise in 

 this way, or that are formed by metamorphosis, are produced 

 at one effort, as it were, and entire. And in the same way 

 are engendered both those creatures that are said to arise spon- 

 taneously, by chance or accident, and derive their first matter 

 or take their origin from putrefaction, filth, excrement, dew, or 

 the parts of plants and animals, as well as those that arise con- 

 generately from the semen of animals. Because this is com- 

 mon to all living creatures, viz. : that they derive their origin 

 either from semen or eggs, whether this semen have proceeded 

 from others of the same kind, or have come by chance or some- 

 thing else. For what sometimes happens in art occasionally 

 occurs in nature also; those things, namely, take place by 

 chance or accident which otherwise are brought about by art. Of 

 this Aristotle 2 quotes health as an illustration. And the thing 

 is not different as respects the generation, in so far as it is from 

 seed, of certain animals : their semiua are either present by 

 accident, or they proceed from an univocal agent of the same 

 kind. For even in fortuitous semina there is an inherent motive 

 principle of generation, which procreates from itself and of 

 itself; and this is the same as that which is found in the semina 

 of congenerative animals, a power, to wit, of forming a living 

 creature. But of this matter we shall have more to say shortly. 

 From what has just been said, however, several paradoxes 

 present themselves for consideration. For when we see the 

 cicatricula enlarging in the egg, the colliquament concocted 



1 Hist. Anim. lib. v, cap. 28. 4 Metaph. lib. vii, cap. 9. 



