The Organization of the Egg 



189 



the generally accepted doctrine of piefoniialion, according 

 to which the adult animal was present in miniature within 

 the egg or the sperm cell, both of which had their advocates, 

 so that embryologists were divided into the rival schools of 

 "ovists" and "spermatists. " One enthusiastic and imagina- 

 tive observer even pictured a miniature human body within 

 the spermatozoon. 



sp 



BERoii 



Showing tlie four rows of swiinuiing ]>lntes, sj 

 Chun. 



Vrom Lankosfcr, after 



While such fancies have long since been laid to rest, pre- 

 formation, in a new dress, is playing a very important role 

 on the biological stage today. The importance of this theory 

 is due largely to the work of two American biologists — 

 Morgan at Columbia and Conklin at Princeton. 



In modern form preformation assumes the presence in the 

 sex cells of certain formative stutfs or entities (more exact 

 terminology is impossible in the present state of our knowl- 

 edge) which determine the development of parts or features 

 of the adult organism. These things, whatever they are, may 

 reside either in the nucleus or the cytoplasm. In the former 



