THE ULTIMATE SEX-ELEMENTS. jg 



to have preexisted in the egg. In 1677, Leeuwenhock was led by 

 Hamm to the discovery of the spermatozoa; and this was followed 

 up, though not to much profit, by Vallisneri and others. Steno, too, 

 in 1664, had given the ovary its present designation; and De Graaf 

 had interpreted the vesicles of this organ, which now bear his name, 

 as for the most part equivalent to the ova which he had discovered 

 in the oviduct. Needham (1667), Swammerdam (1685), and J. van 

 Heme, also contributed items of information not then appreciated in 

 their real relations. 



(V) The Theory of Preformation. — Ovists and Animalcnlists. — 

 In the early part of the eighteenth century, the embryological 

 observations of investigaters, like Boerhaave, were summed up in the 

 conception that development was merely an expansion or unfolding 

 of a preexistent or preformed rudiment within the egg. Harvey had 

 indeed striven for an opposite conclusion; but his view was negatived, 

 as we have seen, by Malpighi's failure to trace the embryo beyond the 

 rudiments of the cicatricula. 



The notion of a preformed rudiment, thus suggested by Boerhaave, 

 Malpighi, and others, rapidly became the prevalent theory. In so 

 far as it emphasizes one side of the facts, it is bound in modified form 

 so to remain. Leibnitz, Malebranche, and others, found it to fit in 

 better with their cosmic conceptions than the older view of Aristotle 

 had done, and welcomed it accordingly. 



The positions occupied by the physiologist Haller well illustrate 

 the alterations of opinion. As Allen Thomson points out in his 

 article "Embryology," in the Encyclopedia Britannica, "Haller was 

 originally educated as a believer in the doctrine of ' preformation ' by 

 his teacher Boerhaave, but was soon led to abandon that view in favor 

 of ' epigenesis ' or new formation. But some years later, and after 

 having been engaged in observing the phenomena of development in 

 the incubated egg, he again changed his views, and during the 

 remainder of his life was a keen opponent of the system of epigenesis, 

 and a defender and exponent of the theory of 'evolution,' as it was 

 then named." 



The preformation theory found more and more definite expression 

 in the works of Bonnet, Buffon, and others. It is now necessary to 

 sum up its main propositions. 



The germ, whether egg-cell or seed, was believed to be a minia- 

 ture model of the adult. " Preformed " in all transparency lay within 

 the egg the future organs, only requiring to be unfolded. Bonnet 

 affirmed that before fertilization there lay within the fowl's ovum an 

 excessively minute but complete chick. They compared the germ 

 to a complex bud, which hides within its hull the floral organs or 



