244 GERM-CELL CYCLE IN ANIMALS 



as a definite, visible substance ? We know from the 

 investigations of Meves (1911) that the plastosomes 

 in the spermatozoon are carried into the egg, in the 

 case of Ascaris, and there fuse with the plastosomes 

 of the ovum. Whether keimbahn-determinants act 

 in a similar manner is unknown. There are, how- 

 ever, certain cytoplasmic inclusions in the male 

 germ cells that have been compared with similar 

 structures in the oocytes, for example, the chromatic 

 body described by Buchner (1909) in the spermato- 

 genesis of Gryllus (see p. 88), and the plasmosome 

 which is cast out of the nucleus of the second sperma- 

 togonia in Periplaneta and disintegrates in the cy- 

 toplasm (Morse, 1909). That keimbahn-determi- 

 nants from the spermatozoon are not necessary for 

 the normal production of germ cells is of course evi- 

 dent, since some of the species with which we are 

 best acquainted, for example, Miastor, are partheno- 

 genetic. 



