OVARY AND OVARIAN EGG OF ANOPHELES 429 
the separated branch, and the nucleus then produces more 
branches which in their turn become separated, so that ‘ der 
protoplasmatische Leib der Hizelle auf Kosten des Hikernes 
wichst ’. This, however, is not a case of the degeneration of 
the nucleus, as it continues to increase in size while it is giving 
up these portions of its substance. Therefore this mechanism 
of nutrition is practically the same as in A. maculipennis, 
except that im this case the nucleus continually passes portions 
of its substance into the growing oocyte as nutritive material 
instead of merely conducting nutritive fluid to the oocyte. 
In Calliphora erythrocephala Towne (16) describes 
another manner by which the oocyte receives portions of the 
nucleus as nutritive material. He says that ‘ When the ege 
is enlarged to about two-thirds of its maximum size the granules 
in the largest nucleus appear to stream out, the nucleus itself 
shrivels and is ultimately lost, whilst the whole protoplasm 
of the cell assumes a granular yolk-like appearance, in which 
the nuclear granules can no longer be distinguished’. The 
‘largest nucleus ’ is evidently the oocyte nucleus, the remainder 
being those of the nurse-cells. A similar passage of granules 
from the nucleus has been observed in the oocytes of many 
insects. 
A modification of this process of nutrition has been observed 
by Gatenby (8) in the oocyte of Apanteles. In this, minute 
solid chromatoid granules first appear, and later a nuclear 
membrane appears round each of these. These grow and a lirin 
network appears, and the larger nuclei so formed resemble the 
true oocyte nucleus to the smallest details. These secondary 
nuclei disappear when nutrition is complete. 
In Rhizotrogus solstitialis Rabes (24) describes 
a very different mode of nutrition. In this the nutrition of the 
oocyte is not confined to the nucleus and nurse-cells, the 
follicular epithelium playing an important réle. As the oocyte 
grows the epithelium forms folds which penetrate into the 
volk-mass, often ag far as the middle of the oocyte, an excellent 
exainple of the tendency to increase the surface of contact 
between the oocyte and secretory structure, 
