STUDIES ON GERM CELLS 483 



are definitely segregated. What becomes of them during the 

 comparatively long period between their disappearance in the 

 primordial germ cells and their reappearance in the oocytes or 

 mature eggs can only be conjectured. They seem to disinte- 

 grate into very fine particles which become thoroughly scattered 

 within the cell body and mixed with the cytoplasm. It has been 

 suggested (p. 397) that they may retain their physiological 

 characteristics and become concentrated again in the growing 

 oocytes into morphologically similar bodies, increasing 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 cope- 

 pods, be temporary structures, produced at a certain time and 

 place under similar metabolic conditions, and becoming associated 

 with particular parts of the cell contents, may 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 mechan- 

 ism for their definite unequal division. These facts argue against 

 the theory that these cast out chromatin bodies serve as determi- 

 nants 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 cytoplasm lacks this material (Montgomery, 

 '11, p. 792). However, the fact that during the early cleavage 

 divisions in some animals (p. 465) large amounts of chromatin 

 escape from the nucleus and are differentially distributed to the 

 daughter cells, is evidence that nuclear material may play some 

 important role in the progressive changes of cleavage cells. 



It has been shown that in many animals the germ cells do not 

 multiply for a considerable period during the early developmental 

 stages. This period also coincides with that during which the 

 Keimbahn-determinants, as a rule, disappear. For example, 

 the germ cells of Chrysomelid beetles multiply until there are 

 about sixty-four present, at which time they constitute a group 



