244 GERM-CELL CYCLE IN ANIMALS 
as a definite, visible substance ? We know from the 
investigations of Meves (1911) that the plastosomes 
in the spermatozoén 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 odcytes, 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 spermatozo6n 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. 
