SEVENTEENTH AND EIGHTEENTH CENTURIES 145 



His preformation theory 

 Of Bonnet's scientific theories the best known is his thoroughly worked- 

 out preformation theory. His "incapsulation" theory, according to which 

 every female individual contains within her the "germs" of all the creatures 

 that originate from her, the one generation within the other, and that thus 

 the first female of every species contained within her all the individuals of 

 that species that have ever been produced and that will be produced until 

 the end of time — this theory is really the very foundation on which all 

 his biological speculation was built. He found actual support for it in his 

 observations of the reproduction of the Aphididre; in the parthenogeneti ally 

 produced, new-born female of the plant-louse he saw the ready-formed rudi- 

 ments of a new generation, and even the metamorphosing insect shows the 

 imago ready formed beneath the pupal skin. In the plant, on the other hand, 

 the germ and the cotyledons are visible in the seed, and the bud encloses 

 the leaves that are to emanate from it. He therefore considered himself fully 

 justified in seeing in these facts a universal law governing the whole of ani- 

 mate nature; he is strongly opposed to all epi genetic theories and character- 

 izes as legends the observations purporting to show that in the embryo of 

 the chicken certain organs are developed before others. However, it is never 

 made quite clear whether these germs, which thus exist in infinite numbers 

 incapsulated within one another, are to be regarded purely corporeally or 

 whether they are some kind of ideal entities after the manner of Aristotle. 

 Bonnet, as a matter of fact, draws quite a number of his theories from Aris- 

 totle, starting from that of the ultimate cause, God or the supreme intelli- 

 gence, and of the harmony and finality of the universe. At all events, the 

 germs exist not only in the ovaries of the females, but also, in some animals 

 at any rate, scattered all over the body. There is, in fact, no other way by 

 which Bonnet can explain how the bits of a cut-up earthworm are regen- 

 erated into new individuals; for the earthworm must, like all animals, be 

 assumed to possess a soul, and the soul is always one and indivisible; if, 

 then, the earthworm is to be regenerated, germs possessing soul-rudiments 

 must lie scattered throughout the body. Indeed, even a separate extremity 

 that is regenerated, as in the crayfish, for instance, must possess a separate 

 germ which is intended to replace it when it is lost, and the same holds 

 good for individual muscles and fibres, which are capable of growing again 

 even in the highest animal forms. — The whole of this germ theory is clearly 

 reminiscent of Leibniz's monad theory and thus has its origin in common 

 with both BufFon's and La Mettrie's doctrines of living particles filling the 

 universe; but while the two latter sceptics utilized the hypothesis to estab- 

 lish a theory of primal creation (spontaneous generation), thereby abandon- 

 ing the personal creator, the fervently religious Bonnet strongly repudiates 

 all idea of spontaneous generation and gives a number of reasons against 



