240 GERM-CELL CYCLE IN ANIMALS 
so far as the segregation of the keimbahn-determi- 
nants in cleavage cells is concerned, but the move- 
ment of the egg contents seems to be a more probable 
cause of localization. 
C. Tue Fate or THE KEIMBAHN-DETERMINANTS 
It is unfortunately impossible to trace the keim- 
bahn-determinants throughout the entire germ-cell 
cycle. The question of their fate, however, is an 
important one. As we have seen, they become vis- 
ibly apparent shortly before or just after the inaugu- 
ration of the maturation divisions, and remain intact 
for a brief period during the early cleavage stages. 
They persist in insects as definitely recognizable 
granules (Fig. 37, F) for some time after the primor- 
dial germ cells are segregated; then they gradually 
break up into finer particles, leaving no trace of their 
existence behind except in so far as they give the 
cytoplasm of the germ cells a greater affinity for 
certain dyes. In Chironomus they may still form 
distinct masses after the definitive germ glands 
have been formed (Fig. 33, D). The ectosomes in 
the copepods are temporary bodies which appear 
to rise de novo during the formation of each mitotic 
figure in the early cleavage stages, then break down 
and disappear. Practically all of the other keim- 
bahn-determinants persist during early cleavage and 
then disappear as distinct visible bodies as soon as the 
primordial germ cells are definitely segregated. What 
becomes of them during the comparatively long 
period between their disappearance in the primordial 
