OOGENESIS IN PHILOSAMIA 19 
of emergence. In a few of the youngest eggs in this material, 
the spireme is still vaguely discernible (fig. 61) in the form of 
a pale network of irregular threads joined together, not the 
coiled spireme of earlier eggs. Several dark bodies of irregular 
size and shape are characteristic of this period. In figure 62 
—a slightly older nucleus in the same string—all traces of the 
spireme have disappeared. The nuclear cavity contains a pale 
body with a large vacuole, and numerous smaller rounded masses, 
which frequently stain very deeply. These are probably all 
plasmosomes. There is extreme variability in respect to their 
number, size and appearance, some being apparently homo- 
geneous, others filled with vacuoles. Figure 63 is a nucleus of 
about the same age as figure 62. 
As the eggs increase in size, the nuclei appear to have at one 
side a darker region, frequently crescentic (fig. 64), which seems 
to be connected with a dark granular protoplasmic strand run- 
ning down into the cytoplasmic region of the egg, now cone- 
shaped, as in the mature egg. The nucleus is party surrounded 
by yolk spheres, lying in faintly granular cytoplasm. The cres- 
centic region merges gradually into the lighter granular portion 
of the nucleus, and suggests merely a condensation of the nucleo- 
plasm here. Over twenty-five nuclei of this stage were examined, 
after varying degrees of extraction. In many cases the contents 
of the darker region were visible, and all showed the same condi- 
tion of darker granules merging into lighter ones. No plasmo- 
somes were to be seen, nor any trace of chromatin. The nuclei 
lie near the periphery of the eggs in the cytoplasmic region near 
the nurse cells, which at this time are reduced to shrunken rem- 
nants. Later the nuclear wall seems to fade out at the side 
nearest the periphery, and several bipartite rod-like chromosomes 
may be seen within the nucleus. At a slightly later period, 
the chromosomes, now shorter and more dumb-bell-shaped, ap- 
pear to lie in a rounded area in which no distinct nuclear bound- 
ary is discernible. In the latest prophase (fig. 3) the nuclear 
boundary reappears, very faint, and very much smaller than 
the former nuclear area. 
