EGGS AND OVIPOSITION. 
The mode of disposal of the eggs shows wide diversities in different genera and 
species and these affect the entire life-history of the species. The method of 
oviposition best known is that of the typical species of Culex, and this is shared 
by Culiseta, Lutzia, Mansonia and Uranotenia. In these forms the female lays 
all her eggs at one time, grouping them together in the so-called raft or egg- 
boat. These eggs are cylindrical, rounded at the ends, and taper slightly 
towards one end. The eggs are placed in an upright position with the larger 
end downward and are fastened together along their sides by a viscous secretion 
which quickly hardens. The slight upward taper of the eggs brings about the 
characteristic convexity of the bottom of the egg-raft and this prevents it from 
being overturned. These egg-rafts are deposited either upon the water or close 
to it. We have found egg-masses of Culex upon the sides of rain-water barrels, 
some distance above the surface of the water. Egg-masses so placed are probably 
carried to the water by rain-water, or perhaps even water from a heavy dew, 
trickling down the walls of the barrel. 
Réaumur, in his classic work, gives a detailed and most interesting account of 
the egg-laying process in the common house-mosquito, Culex pipiens. The 
account of this wonderful observer is so faithful that we reproduce it here: 
“Towards the end of May I left my laboratory work at about 6 o’clock 
in the morning, to watch the mosquitoes. The thermometer stood at 13-1/2 
degrees . . . On arriving I first noticed more than thirty egg-masses which had 
just been laid, but fortunately I saw also a mosquito which had not yet finished 
oviposition. This mosquito was clinging by her four anterior legs to a bit of 
leaf touching the side of the bucket. Her body was above the leaf, the penulti- 
mate segment touching the water. A raft of eggs which was placed near the end 
of her body and which had not yet reached full size indicated that the laying was 
well advanced but not yet finished. The mosquito, busy with this important 
measure, did not notice my presence, and permitted me to approach near enough 
to her to watch her through a strong lens. I soon knew how it happens that the 
eggs are placed perpendicularly to the surface of the water and how they are ar- 
ranged. It is the end of the abdomen which does it all. We have said that the 
penultimate segment of the body touches the water, and we can now say that the 
last segment (that which carries the anus) forms with the rest of the body a kind 
of hook elevated a little above the surface of the water. From this last segment, 
thus turned up, I soon saw an egg come out; I saw that it came out in a different 
direction from that in which the eggs ordinarily issue with other insects. The 
latter are placed horizontally, or lying down, while these are placed upright, 
in a vertical direction. The egg issues very near the mass of eggs already put 
in place. As soon as it is entirely, or almost entirely out, the mosquito has only 
to push it against those of the little boat which it is nearest to; for this egg, like 
those of almost all insects, are without doubt provided with a sticky substance 
which fastens it to the object to which it is applied. 
“The laying of an egg and the placing it in position is for the mosquito an 
affair of an instant, and as soon as she has placed one another begins to issue 
from her body. The mosquito which I observed laid in this way, without inter- 
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