KEIMBAHN-DETERMINANTS 241 



germ cells and their reappearance in the oocytes or 

 mature eggs can only be conjectured. They seem to 

 disintegrate into very fine particles which become 

 thoroughly scattered within the cell body and mixed 

 with the cytoplasm. It has been suggested (p. 68) 

 that they may retain their physiological characteris- 

 tics and become concentrated again in the growing 

 oocytes into morphologically similar bodies, in- 

 creasing in the meantime, by multiplication or in 

 some other way, until they equal in mass those of 

 the preceding generation of germ cells. On the other 

 hand, they may all, like the ectosomes of copepods, 

 be temporary structures produced at a certain time 

 and place under similar metabolic conditions, and, 

 becoming associated with particular parts of the 

 cell contents, thus be constant in their distribution. 

 Several ideas have been advanced regarding the 

 fate of the eliminated chromatin in Ascaris. The 

 ends of the chromosomes which are cast out into the 

 cytoplasm are not equally distributed among the 

 daughter cells nor does there appear to be any mech- 

 anism for their definite unequal division. These 

 facts argue against the theory that these cast-out 

 chromatin bodies serve as determinants and also 

 make improbable the hypothesis that they enable 

 the somatic cells to differentiate, whereas the germ 

 cells which do not undergo the diminution process 

 remain in an indifferent condition, since their cyto- 

 plasm lacks this material (Montgomery, 1911, p. 792). 

 However, the fact that during the early cleavage 

 divisions in some animals (see p. 218) large amounts 



