GERM CELLS IN THE ARTHROPODA 159 
but soon after it reaches a sphere-like shape it begins 
to vacuolate and becomes irregular (Figs. 46, K; 47). 
It also seems probable that in some odcytes the 
odcyte spindle gives rise to the keimbahn-chromatin, 
whereas in others it becomes disorganized, forming 
the nucleus of the egg (Fig. 47, A, B, C). What 
causes the difference in the history of the odcyte 
spindles? No definite answer can be given to this 
question, but there are two possibilities, (1) external 
and (2) internal influences. It seems very improb- 
able that any internal mechanism exists which 
determines what the history of the odcyte spindle 
shall be. On the other hand, the arrangement of 
the odcytes in the ovary might cause the spindle of 
those most posteriorly situated to become keimbahn- 
chromatin and of those next in order to transform 
into nuclei. According to this view the odcytes de- 
pend upon chance for their final position in the 
ovary, and the fate of the spindle is decided by the 
environment of the odcyte. 
There are numerous cases of cell fusion in both 
Protozoa and Mrrazoa, and germ cells and somatic 
cells. For example, Protozoa engulf other cells; 
the fully grown ova of Hydra consist of several 
germ cells fused together; and leucocytes may fuse 
with one another. In all such cases the nucleus of 
one cell persists, whereas those of the other cells 
disintegrate and disappear. Among certain leuco- 
cytes of Avolotl, however, Walker (1907) has de- 
scribed a sort of fusion which results in the trans- 
ference of the chromatin from one cell to another 
