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MONICA TAYLOR. 
of any polar bodies. The egg nucleus lies in the middle of 
the egg, and is a typical resting nucleus. It is surrounded 
by the large yolk globules which constitute the greater bulk 
of the egg. The cytoplasm, which is sparse, is densely 
staining and provided with numerous deeply-stained particles, 
as was the case in the tissues of the larva and pupa, and 
there are large numbers of small bodies surrounding the 
yolk globules which resemble chromatin in their staining 
reactions. These chromatin-like bodies, “ yolk nuclei ”, seem 
to be intimately concerned with the digestion of the globular 
yolk-masses, and with their conversion into protoplasm, and 
sometimes resemble very minute chromosomes (PI. 20, fig. 1). 
When surrounded by the digestion products, which have 
resulted from their activity, they do not stain so clearly, and 
eventually they appear in the fully-formed protoplasm as the 
particles already described. This quality of the protoplasm 
greatly detracts from the beauty of the histology. 
The sperm nucleus (male pro-nucleus) assumes the resting 
condition very quickly. In one egg of a raft, fixed a few 
minutes after deposition, the two pro-nuclei are already in 
close contact. In one egg of a raft half an hour old, the 
spermatozoan has reached the egg nucleus, but is still sperm- 
like. In one-hour rafts there are several segmentation 
nuclei. (It must be remembered that there is a difference in 
age between the first laid egg of the raft and the last laid 
egg, of from ten to twenty minutes, hence these times are only 
approximate.) 
The segmentation nuclei, which lie in little islands of 
protoplasm (PI. 20, fig. 2) pass into a decided resting-stage 
after dividing, and several blocks have to be sectioned to 
make sure of obtaining mitotic nuclei. 
The prophases (PI. 20, figs. 4-9) of the dividing segmenta- 
tion nuclei of Culex show six chromosomes. In early 
prophase a tendency to emerge in pairs from the resting 
nucleus is evident (PI. 20, fig. 9). These six chromosomes 
(PI. 20, fig. 10) arrange themselves on the equator of a 
perfectly typical spindle, split longitudinally, and in anaphase 
