GERM CELLS IN THE ARTHROPODA 155 
tion. This may now be recognized as the “nucleolo”’ 
of Silvestri or the keimbahn-chromatin as we have 
decided to call it. 
The spindle at first lies nearer the anterior than 
the posterior part of the odcyte. As it shortens 
and condenses it is more often found below the middle 
of the cell, and finally reaches a position near the 
posterior end. The conclusion is thus reached that 
the “nucleolo” of Silvestri is not a plasmosome 
(metanucleolus) which escapes from the odcyte 
nucleus, but consists of all of the chromatin of this 
nucleus condensed into a more or less spherical body 
during a peculiar process of spindle formation. 
The discovery of the origin and nature of the keim- 
bahn-chromatin brought forth a new problem, 
namely, that of the origin of the egg nucleus. It 
was early noted that the odcytes containing this 
peculiar spindle were free from any other inclusions 
in the cytoplasm. How then do they acquire a 
nucleus? Two hypotheses have been considered, 
one of which has a considerable body of evidence in 
its support. In the first place the nucleus might 
arise from chromatin granules which break away from 
the chromosomes during the formation or conden- 
sation of the spindle. There is, however, no evidence 
for this view, since the entire chromatin content of 
the odcyte nucleus seems to take part in the forma- 
tion of the spindle and later the keimbahn-chromatin. 
The second hypothesis was suggested when a number 
of cases were discovered of two odcytes lying end 
to end without any intervening follicular epithelium. 
