422, A. J. NICHOLSON 
to discover, and it occurs when the egg-follicle is about a third 
of its full size. It now becomes lost in the yolk-mass from 
which stains will no longer differentiate it. It does not follow, 
however, that because it is ne longer visible it has therefore 
ceased to exist as a separate entity. 
A little later, after the nurse-cells have heen extruded, 
a small mass of protoplasm which is free from yolk is found 
situated a little behind the anterior extremity of the egg, 
that is, approximately in the position in which the chromatin 
residue disappeared. The central portion of this mass is rather 
denser than the remainder, and this I regard as the derivative 
of the chromatin residue. Some eggs were sectionized which 
had been fixed about an hour after laying. In these a number 
of minute chromosomes were found situated in the denser 
central portion of the above-mentioned mass. It would there- 
fore appear that the reconstruction of the chromosomes takes 
place shortly after the fertilization of the egg, a process which 
frequently occurs in insect eggs. 
As the chromatin residue was derived from the chromatin 
of the spireme, and as after fertilization the reconstruction of 
the chromosomes takes place in the anteriorly-placed mass of 
protoplasm which is free from yolk, it seems a reasonable 
assumption that this mass contains the derivative of the 
chromatin residue. 
iL Yolk FPormationjand the Nutrition @ieibe 
Oocyte. 
Shortly after the egg-follicle enters the second period of 
growth the oocyte commences to enlarge and soon occupies 
about half of the egg-follicle, the nurse-cells occupying the 
other half. At this stage yolk begins to make its appearance. 
Virst the cytoplasm is seen to contain a number of small 
globules which do not stain. These enlarge and are then recog- 
nized as fine yolk. Immediately after this granules of coarse 
yolk make their appearance, usually forming a zone midway 
between the nucleus and the periphery of the oocyte. These 
granules are very small, but they increase in size as the oocyte 
