400 HISTORY OF THEORIES 



back on a metaphysical conception of inheritance and develop- 

 ment. " Not only is there a soul or vital principle present in 

 the vegetative part, but even before this there is inherent mind, 

 foresight, and understanding, which, from the very commence- 

 ment to the being and perfect formation of the chick, dispose and 

 order and take up all things requisite, moulding them in the new 

 being, with consummate art, into the form and likeness of its 

 parents." 



(c) " Preformationist " Theories. — During the seventeenth 

 and eighteenth centuries, and even within the limits of the nine- 

 teenth, a theory of inheritance and development prevailed, 

 according to which the germ (either the ovum or the sperm), 

 contained a miniature organism, pre-formed though invisible, 

 which only required to be unfolded (" evolved ") in order to 

 become the future animal. 



Moreover, the egg of a fowl contained not only a micro-organism 

 or miniature model of the chick, but likewise, in increasing 

 minuteness, similar models of future generations. Thus the rash 

 theorists pointed out that Mother Eve must have included 

 1,543,657 — or, according to another computation, 200,000 million 

 — homunculi ; and, what was still more rash, they figured the 

 miniature homunculus which lay within the sperm. The "ovists," 

 who held that the ovum contained the miniature, did battle 

 with the " animalculists," who supported the claims of the 

 sperm ; but both schools agreed in the general idea, that 

 microcosm lay within microcosm, germ within germ, like the 

 leaves within a bud awaiting successive unfolding, or like an 

 infinite juggler's-box, to the " evolution " of which there was no 

 end. 



A thoroughgoing representative of the preformationist school 

 was Charles Bonnet (1720-93), who discovered the partheno- 

 genesis of green-flies, and made many important observations 

 on polyps and worms, but after the failure of his eyesight became 

 more exclusively a speculative thinker. He pondered over 



