OOGENESIS IN PHILOSAMIA DAI 
cells. The egg spireme is not continuous, but is composed of 
the haploid number of interlaced threads, which have not yet 
contracted. Marshall (07) found a still later differentiation 
in Platyphylax, a neuropteran, in which the tetrad stage is 
common to both kinds of cells, but the egg cell is larger, and 
the tetrads persist longer before disintegration. 
The haploid number of chromatin segments is present in the 
nurse cells of P. cynthia, as in Pieris (Doncaster 712), indicating 
a preparation for division in these cells whose function is only 
nutritive. A number of writers, including Grinberg (’03), 
Gross (’03), Marshall (’07), and Woltereck (’98), figure tetrads in 
the nurse cells of various animals, but do not state whether the 
haploid number is present. They agree, however, that differ- 
entiation of eggs and nurse cells occurs after synapsis, which 
would imply that nurse cells as well as eggs must have under- 
gone pseudo-reduction. 
A transfer of material takes place from the nurse cells and the 
egg through the connecting tubes which in P. cynthia have very 
prominent walls. A markedly similar condition was observed 
by Ginthert (10) in Dytiscus, where converging bundles of 
fibrils appear, beset with chromidia or chromatin granules which 
enter the egg. In this case there is no definite wall to the tubes. 
Grinberg (’03) states that in Pieris: the egg sends a large blunt 
process up between the nearest nurse cells. Evidently there 
is considerable variation in the relation of eggs and nurse cells 
within the Lepidoptera, for in P. cynthia it is the nurse cells 
which send processes into the egg. 
The history of the egg nucleus seems to show that the chromo- 
somes lose their visible identity during the growth period. I am 
convinced of the accuracy of the results in this particular, on 
account of the very careful study given to this stage. More 
than half the nuclei from one individual were examined, and 
only in the very earliest eggs were traces of spiremes to be found. 
I examined also egg strings of other moths. In Clisiocampa 
the spireme persists relatively longer, being found in large eggs. 
As in P. cynthia, it becomes gradually fainter and more broken 
the older the eggs become, and finally disappears altogether. 
