OVARY AND OVARIAN EGG OF ANOPHELES 433 
nucleolus, giving rise to a ‘ double nucleolus’. Later one side 
of the nucleolus is formed of chromatin and the other is the 
plasmosome. 
Gatenby (8) shows that in Apanteles glomeratus the 
division of the oocyte nucleus into germinal and vegetative 
parts takes place in a very different manner. Secondary nuclei 
are produced, apparently arising from material which has 
escaped from the true oocyte nucleus, and these are found round 
the periphery of the oocyte. Then ‘some time before the 
ovarian oocyte has become ripe the secondary nuclei disappear 
by a process of degeneration or chroniatolysis ’. The secondary 
nuclei are considered to influence the production of yolk. 
Discussing this subject Gatenby remarks: ‘The egg nucleus 
of many insects, of which Apanteles is an example, becomes 
partly decentralized ; this is te say, the nucleus, instead of 
influencing various processes of oogenesis from afar, sends 
pieces of itself into the furthermost regions of the egg, which 
carry on part of the vegetative functions at least of the 
chromatin of the ordinary nucleus.’ This statement applies 
equally well to the oocyte nucleus of A. maculipennis, 
though the pieces sent ‘into the furthermost regions of the 
egg’ remain attached to the rest of the nucleus. 
It has already been shown that, though there is good reason 
to believe that the ‘chromatin residue’ gives rise to the 
segmentation nucleus, there is a period in which no chromatin 
matter can be distinguished, and the oocyte of the mosquito 
then appears to be without a nucleus. A similar phenomenon 
has been encountered in the oocytes of other insects by many 
observers. Will (84) states that the oocyte nucleus of Dytis- 
cus becomes a mass of fine granules from a small portion 
of which the ‘ definitive Kern’ is later produced. Lowne (16), 
speaking of Calliphora erythrocephala, remarks, 
‘In the ripe unimpregnated ovum I have entirely failed to 
find any nuclei or cellular elements of any kind, and I feel sure 
that if any such elements were present they would readily 
be distinguished in my sections’. Lubosch (17) states that 
this disappearance of the staining portions of the oocyte 
