JHE ULTIMATE SFX-ELEMENTS. 83 



indeed begun. Thus, as Allen Thomson notes, Volcher Goiter 

 of Groningen (1573), along with Aldrovandus of Bologna, had 

 Avatched the incubated egg in its marvellous progress from day 

 to day. Fabricius ab Aquapendente (1621) had also studied 

 the changes in the incubated egg, and the stages of the 

 mammalian foetus. In keenness of vision, Harvey was far 

 ahead of either of these. 



(/») Malpighi (1672), using a microscope with phenomenal 

 skill, traced the embryo back into the recesses of the cicatricula 

 or rudiment, but again missed a magnificent discovery, and 

 supposed the rudiments to have pre-existed 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 dis- 

 covered in the oviduct. Needham (1667), Swammerdam (1685), 

 and J. van Heme, also contributed items of information not 

 then appreciated in their real relations. 



(t) The Theory of Tirforniation — Ovists and AnimaJculists. 

 — In the early part of the eighteenth century, the embryological 

 observations of investigators, like Boerhaave, were summed up 

 in the conception that development was merely an expansion 

 or unfolding of a pre-existent 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 emphasises 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 concep- 

 tions 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 EncydopcEdia 

 Britanuica^ " 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 favour of ' e})igenesis ' or 



