August 30, 1901.] 



SCIENCE 



329 



There are two subjects which every one appears 

 to think can be done by nature. One is editing 

 a newspaper and the other is classifying. Any 

 one who has had any experience in either will 

 feel differently. 



Talcott Williams. 



SHORTER ARTICLES. 



NOTES ON THE LIFE HISTORY OF ANOPHELES 



PUNCTIPENNIS AND ON THE EGG-LAYING 



OF CULEX PIPIENS. 



Some time during the latter part of May, 1901, 

 a ditch about four feet in depth was dug for 

 the water main to the new textile building on 

 the campus. The ditch was dug in sections, 

 one of which ran down a considerable slope 

 just at the end of the photographic building. 

 This section of the ditch soon became partly 

 full of rain water. At the lower end the water 

 was two and a half feet deep, but the water 

 did not extend more than a third of the length 

 of the ditch up the slope. At the upper and 

 shallower end of the body of water, it soon be- 

 came covered with a thin green slime, which 

 upon examination proved to be wholly of Pro- 

 tococcus. In this shallow, slimy water on June 

 4 the writer discovered an abundance of 

 larvse of Anopheles punctipennis. They were 

 recognized at a glance as larvse of Anopheles 

 from Dr. Howard's excellent drawings and de- 

 scriptions of the larvae of Anopheles maculipen- 

 nis. Glass jars were immediately called into 

 requisition, and many larvse were carried to the 

 laboratory, from a study of which the follow- 

 ing notes were made. It might be of interest 

 to say just here that there was also an abun- 

 dance of larvae oiCulexpipiens in the same water 

 in' company with Anopheles. 



Eggs. — It was with some surprise and a good 

 deal of pleasure that a number of eggs were 

 found on the surface of the water in the jars. 

 Like maculipen7iis, they are laid at random on the 

 water, but naturally run together and cohere in 

 loose irregular groups or strings of from three to 

 a score or more. Some were found floating on 

 their sides, but the greater number seemed to be 

 floating with the convex side, or ' back,' up and 

 the concave side down. They differ some- 

 what from the eggs of maculipennis in shape. 

 These eggs resemble an Indian canoe in shape, 



hence a cross section would be more or less 

 triangular in outline. Seen from the side they 

 are strongly convex above and concave below. 

 One end is larger and blunter, while the other, 

 as seen from the side, curves strongly down- 

 ward, is smaller and more pointed. Above and 

 on the sides the eggs are marked with a reticu- 

 late hexagonal sculpturing similar to maculi- 

 pennis. Below, on the concave side is a dark 

 wide line or band, extending nearly the length, 

 of the egg. It widens at each end into a club- 

 like expansion. The writer could not be svire 

 whether this was simply a band or a groove. 

 Near the blunt end of the egg a transparent 

 line runs from each side of the dark band ob- 

 liquely down the sides of the egg. When the 

 egg bursts, it breaks along these lines. At 

 each end of the band are several dark, circular 

 spots. The eggs varied from .45 mm. to .47 

 mm. in length. They hatched in 24 to 48 

 hours after being brought in, but no record was 

 obtained as to the actual time of hatching after 

 being laid, as none of the females laid eggs in 

 captivity. It is probably safe to say, however, 

 that they accord in this particular very closely 

 with maculipennis. 



Larvse. — When first hatched the larvse pre- 

 sent a mottled appearance, owing to alternate 

 dark and light transverse markings on the 

 body. This appearance certainly suggests the 

 spotted wings of the adult, although there per- 

 haps can be no reason for thinking that the 

 one in any way foreshadows the other. The 

 larvse retain this appearance up to the last molt, 

 although it seems to grow less distinct with age. 

 They lie in a nearly horizontal position just 

 beneath the surface film of water, and when 

 only slightly disturbed wriggle in a horizontal 

 direction across the water instead of downward 

 as Culex. When violently disturbed they 

 wriggle downward. The more mature larvse 

 are more inclined to wriggle downward than 

 the young larvse, when disturbed. The feed- 

 ing habits are almost identical with those of 

 maculipennis, so fully described by Dr. Howard. 

 The same rotary motion of the head with the 

 under side uppermost in feeding was charac- 

 teristic. There were no such differences be- 

 tween the larvse of punctipennis and maculi- 

 pennis as there were between the eggs of the 



