KEIMBAHN-DETERMINANTS 221 



of the cast-out chromatin, and there is consequently 

 no grounds for the hypothesis that "in Ascaris those 

 cells which become body cells are the ones that in- 

 clude the cast-off chromosome ends in their cyto- 

 plasm, and it will pro})a})ly be found that these 

 ejected chromosome parts engender such cytoplasmic 

 differentiations as characterize the body cells " 

 (Montgomery, 1911, p. 192). 



Chromidia. To several of the bodies listed in 

 the table on page 88 as keimbahn-determinants has 

 been ascribed an origin from the chromatin of 

 the germinal vesicle. Many cases of the elimination 

 of chromatin from the nuclei of growing oocytes are 

 to be found in the literature. Blochmann (1886) dis- 

 covered a process of "budding" in the oocytes of 

 Camponotus ligniperda resulting in the formation 

 of "Nebenkerne." These appear first as small 

 vacuoles lying near the nucleus ; later they contain 

 small staining granules and acquire a membrane. 

 The "Nebenkerne" grow in size and increase in num- 

 ber, while the nucleus of the oocyte becomes smaller. 

 Stuhlmann (1886) described a similar phenomenon 

 in about a dozen different species of Hymenoptera. 

 The oocyte nucleus in all species examined becomes 

 localized near the anterior end ; then the small 

 nuclear-like bodies form around it at its expense. 

 The time of their i)roduction varies in the differenl 

 species ; in some they appear in the very young 

 eggs ; in others not until a much later stage has been 

 reached. Sometimes they fuse to form a large 

 "Dotterkern" lying at the posterior pole of the egg; 



