42 



establish the theory. They only suggest it. Some of the 

 "b as i chromatin in the nucleus of the spermatid is dissolved 

 by the oxychrooatin and transferred to the capsule. After 

 the capsule is everted into the egg and has entered the cyto- 

 plasm of the latter, the b^sichromatin is redeposited and 

 thus the granular structure of the male pronucleus appears. 

 It may be possible to explain the number of chromosomes that 

 appear by supposing that there are a certain number of dif- 

 ferent kinds of molecules which are deposited out of the 

 oxyohromatin and that these have such an affinity for each 

 other that they are aggregated into a definite number of 

 groups or they may be of such a structural nature than they 

 can fall only into certain groups. Of course, I claim for 

 this only that it Is a possible explanation of phenomena 

 which are apparently not In accord with the conception of an 

 individual continuity of the chromosomes. 



Z. SUMMARY. 



1. The seminal elements in Menlppe mercenaria arise 

 from a single row of primary spermatagonlal cells which per- 

 sist along one side of the testicular tubule. 



2. The tubule is divided into three or four regions by 

 longitudinal partitions composed of epithelial cells. The 

 seminal elements in the division next to the row of spermato- 

 gonlal cells, are younger than those in any other division. 

 The region on the opposite side contains mature sperms. The 

 seminal elements In one end of a given division are further 



