OOGENESIS IN PHILOSAMIA 1% 
nurse cells, first definitely formed at the periphery of the egg 
string, then growing in at the base of the egg cell. Later they 
erow in between the egg and its nurse cells, separating them 
except in the region of the tubes. 
Stage.l. At the end of the growth period, when the nurse 
cells have become very small, no definite tubes are seen, the 
cytoplasm opening broadly into the egg. Later the follicle 
cells form a continuous layer over the egg, and the nurse cells 
may be seen as small degenerated masses of cytoplasm which 
eventually disappear. 
d. Development of egg cells 
The further history of the egg cells, beginning with their differ- 
entiation from the nurse cells in Stage f is given below. 
Stage f: Post-synaptic spireme. Among the nurse cells of 
this stage (figs. 44-46) a few cells may be observed in every 
section, in which the spireme appears to be thicker than in the 
surrounding celis, more continuous and more closely convoluted, 
as in figure 58. The nucleus is somewhat larger, and is very 
frequently distinguished by a pale yellowish tinge. Character- 
istic of this stage is the large plasmosome, frequently surrounded 
by a darker rim. The cytoplasm is also slightly greater in 
amount. A large number of sections were examined, and these 
differences appeared fairly constant. Careful study of cells 
in the earlier contracted spireme failed to reveal any criterion 
by which the egg cells might be identified at this time. 
After the nurse cells are well differentiated, the spireme of 
the egg cell appears much less convoluted (fg. 59 A), spreading 
out through the nuclear cavity, which has increased considerably 
in size. In figure 59 B is shown a portion of the spireme which 
was not included in the first section. It is not possible to deter- 
mine accurately if the spireme is continuous, but it is my belief 
that this is the case. During this period, one or two large plas- 
mosomes May appear, and frequently two smaller bodies, prob- 
ably of the same nature. The entire nucleus has the yellow tinge 
noted in the earliest stage of its differentiation. 
JOURNAL OF MORPHOLOGY, VOL. 26, No. 1 
