REAUMUR ON OVIPOSITION 141 



ruplion, more than thirty eggs in less than two minutes ; either because the lay- 

 ing was then finished, or because she was finally disturbed by my presence, she 

 flew away and left the little floating boat upon the water, but the shape of the 

 boat was not as regular as that of the majority of the other egg-boats. I searched 

 further, but could find no other mosquito engaged in laying. However, I had 

 not yet seen everything essential to the operation ; I had been sufficiently in- 

 structed in the method by which the mosquito was able to place each egg per- 

 pendicularly on the surface of the water and to attach it to the mass composed 

 of eggs already laid, but it remained to be found out how the mass is sustained 

 upon the water when the base is still too small in relation to the height, how the 

 first egg is sustained or a small group of only two or three eggs. The mosquitoes 

 which I watched on the folloTvang days at 6 o'clock in the morning or thereabouts 

 gave me a complete explanation of this. I found them occupied in laying, find- 

 ing some in which the oviposition was very advanced and others in which the 

 mass was very small. These latter instructed me sufficiently concerning what 

 occurs at the instant when the first eggs are laid, a moment which is very diffi- 

 cult to observe. Among the mosquitoes which I watched in this operation were 

 several which were clinging with their four anterior legs to the wall of the 

 bucket, and others which, like the first one described, were standing uj^wn a float- 

 ing fragment of leaf. The abdomen in both cases stretched over the surface of 

 the water and touched it only by a part of the penultimate segment. But what 

 was essential to notice was the position of the two hind legs, which are the 

 longest, or rather their positions, for I observed two different positions. The 

 mosquitoes which had almost finished laying and whose little boat was almost 

 completed had these two long legs extended and almost parallel to each other. 

 The end of each one reached to the surface of the water and even a little raised 

 above it, but they were both thrust a little in the water near the end, as though 

 forced by a weight, this weight being that of the little boat. This little boat 

 was, so to speak, on a dock. It was not abandoned to the water. The two legs, 

 like two long beams, sustained it at the surface of the water or a little above the 

 water. The mosquito held this boat in this way while she was adding eggs to it, 

 and she did not set it afloat until all the eggs had been placed. 



" The mosquitoes which had advanced but slightly with egg laying and whose 

 boats had not yet reached half size had their legs in a different position from 

 that of which we have just spoken. Here the legs crossed each other in the form 

 of an X, and the place where they crossed was nearer the anus when the as- 

 semblage of eggs was smaller and the boat was shorter. The interior angle of 

 the legs sustained this little mass of eggs. From this it is easy to divine that 

 when the mosquito lays its first egg the legs are crossed very close to the end 

 of the body so as to support the egg ; that they hold up the eggs which are suc- 

 cessively placed against this one ; that in proportion as the mass of eggs lengthens 

 the space between the place where the legs cross and the end of the abdomen 

 grows ; and that finally the two legs assume a parallel position when the boat is 

 half or more than half done ; and that thus, from the placing of the first egg 

 until the end, the eggs are always held up by the hind legs. It is only when the 

 laying is finished that the mosquito abandons the little boat, which is then in 

 condition to sail without risk." 



One of us (Knab) has observed the process of egg-laying in Culex territans 



and found that it agrees substantially with the account of Reaumur. St. George 



Gray, in the Journal of Tropical Medicine, vol. 6, page 313, has described the 



remarkable manner of forming the egg-raft in an African mosquito. 



" The fore and mid legs of the mosquito rested on a couple of the egg-rafts 

 that had been deposited at an earlier hour, and the two hind legs were stretched 



