OVARY AND OVARIAN EGG OF ANOPHELES 401 
anal extremity has enlarged somewhat owing to the erowth 
of the ovary. By the third or fourth day the blood-mass 
is seen to be much reduced, and the whitish mass, the ovaries, 
about half fills the abdomen. The blood-mass is reduced to 
a mere spot or is entirely absent by the sixth or seventh day, 
and, if the weather is warm enough, the eggs are then laid 
during the night. In cold weather, however, the insects may 
wait several days before oviposition. 
These observations were made on a number of insects 
collected in a calf-pen. At the time of collection their abdo- 
mens contained semi-transparent blood-masses and they had 
only recently fed. They were kept in jars in the laboratory 
and the eggs were laid though they received no further food. 
The period elapsing between the time of feeding and ovi- 
position appears to be about a week, which agrees very closely 
with Christophers’s observations on A. rossiin India (8), in 
which case the period is given as six days. 
I only succeeded in observing insects during the process of 
laying in two cases, and in both the eggs were laid within an 
hour of darkness setting in. The insects floated on the water 
by spreading their long legs over it and frequently dipped their 
proboscides into the water. When disturbed they flew off the 
water with ease and seemed in no danger of drowning. The 
actual oviposition I was unable to observe as. the mosquitoes 
refused to lay in the light. 
FrRMALE GENITAL ORGANS. 
In the ‘ resting stage ° the genital organs of the adult female 
inosquito consist of two small ovaries lying ventro-laterally 
in the posterior portion of the abdomen. Each of these com- 
municates posteriorly with an ovarian tube, and the two ovarian 
tubes unite to form a common duct, the gynaecophoric canal, 
which opens to the exterior at the posterior end of the eighth 
segment. A spermatheca, consisting of a thick perforated 
chitinous shell and surrounded by a layer of large clear cells, 
gives off a very thick-walled sperm-duct to the gynaecophoric 
