gg Nelly Evans — Some Observations on the [Auggst, 



animal food after fertilisation, not before. To decide this point ten 

 females were pat alone in the net with the sparrows, all having pre- 

 viously been with males. Of these ten, only four fed, and these four 

 were removed to another cage. They were watched from day to day, 

 and it was noticed that the blood gradually disappeared from the abdo- 

 men, which in all but one assumed the white opaque appearance gen- 

 erally characteristic of mosquitos which are going to lay eggs. In the 

 exception, the abdomen looked transparent and empty. Six days passed 

 and no eggs were laid, and on the seventh day, no mosquitos could 

 be found at all and there were no egg- boats. No dead mosquitos were 

 found either. So that the experiment failed. 



Later on, the same expei'iment was tried with two mosquitos one 

 of which was lost, while the other laid eggs on the fifth day. 



The eggs are generally laid at night, and the followitig night the 

 larvae hatch out. Some mosquitos were i-eared from the egg in the 

 laboratory : the larval stage lasted at least twenty days, and the 

 pupal stage four days. The larvae and pupae were very small and 

 the mosquito was only a third or fourth the size of those reared natur- 

 ally out of doors, while some of the larvae reared in the Museum had 

 not changed to pupae as late as forty-seven days after the eggs were 

 laid. It was found that dessication of the egg-boat for one day was 

 generally sufficient to prevent the larvae from hatching out though one 

 or two larvae did hatch out of an egg-boat which had been dried for 

 six days. 



The egg-boat has been described so often that it is unnecessary to 

 go through its description again. Thei-e is, however, one part of the 

 individual egg which has never been described and that is the structure 

 forming part of the lid. This is best seen in the egg obtained by dis- 

 section of the gravid female mosquito, but only after it has reached a 

 fair size, that is two or three days after the insect has fed. The eggs 

 so obtained will be seen to be capped at the larger end by a transpar- 

 ent dome-shaped structure which is a continuation of the shell of the 

 egg, but not of its whole thickness. It is a very delicate structure 

 and gets damaged very easily. The whole cap is easily broken off and 

 for this reason is rarely seen in eggs after they have been laid, as the 

 caps get broken off in removing them from the water. Tiie function 

 of this cap is probably to act as a float, and to keep that end of the 

 Qgg in contact with the water. Inside and at the base of this dome- 

 shaped cap and in contact with the end of the egg is another peculiar 

 structure. This is a cup-shaped cell, with a hole or depression in the 

 centre, which fits on to a projection at the end of the egg shell, and 

 radiating filaments at the circumference which turn up into the float 



