OVARY AND OVARIAN EGG OF ANOPHELES 397 
indebtedness to Mr. A. J. Grove for the suggestion that I should 
take up this line of research, for much useful advice during 
the earlier stages of my work, and for my first supplies of 
material. For my later supplies I was entirely dependent 
on the kindness of Mr. R. F. Burton, to whom I wish to make 
grateful acknowledgement. 
The work was done under the supervision of Professor 
F. W. Gamble, F.R.S., whom I have to thank for assistance in 
obtaining the very considerable, and not always easily acces- 
sible, literature of the subject. 
MATERIAL AND METHODS. 
The majority of the mosquitoes were taken during the latter 
part of their hibernating period and the first few weeks after 
they had regained their activity and had commenced to feed 
normally. 
In order to eliminate the possibility of being misled by 
artefacts due to fixation, the following method was employed. 
Kach batch of material was divided into three different parts ; 
two of these were fixed in different re-agents, and in the case 
of the third the ovaries were dissected out in salt solution and 
one ovary of each insect was rapidly transferred to one fixative 
and the other to another. In this way the effect of different 
fixatives on ovaries in the same stage of development could 
easily be compared. 
In the cases where the ovaries were not dissected out, the 
abdomen alone was fixed, and this was slit along each side with 
a fine needle in order to allow the easy entrance of the fixative. 
It was found that in the case of the less-developed ovaries 
much the best results were obtained with those which were 
dissected out, but far less distortion was produced in more 
mature ovaries fixed while still im the abdomen. This was 
probably due to the fact that the surrounding tissues only 
allowed the fixative to reach the ovaries gradually and so 
prevented rapid osmosis. 
A number of different fixatives were used, the principal of 
which were Flemming, both with and without acetic, Petrunke- 
