PROPHYLAXIS OF MALARIA. 
47 
cates that drainage of pools or other small collections of water will 
not be efficient if the mud remains moist until water again gains ac¬ 
cess to the pool. The observations of Nuttall and Shipley 11 and of 
Christophers and Stephens , 12 as well as others, prove conclusively 
that the eggs of the Anophelinee will remain alive in moist mud for 
days but that in dried mud they quickly perish. 
The larvae .—The larvae of the Anoplielince are distinguished from 
the larvae of other mosquitoes by the elongated, comparatively narrow 
Fig. 2.—Larva of Anopheles and Culex. 1,Larva of anophelinse. Note horizontal posi¬ 
tion in relation to surface of the water, and the absence of syphon (A). 2, Larva of 
Culex. Note angular position in relation to surface of the waiter, and presence of the 
syphon, at A. (Fig. 1, after Howard; 2, after Theobald.) 
head and the absence of the respiratory tube or siphon. Like the 
adult insect the body is divided into three portions—the head, the 
thorax, and the abdomen. While in the ordinary Culex mosquitoes 
the head is comparatively broad, in the anopheline larvae it is narrow 
and elongated and easily distinguished. The important differential 
point, however, is the great difference in the breathing apparatus, 
the long respiratory tube of Culex and Stegomyia being replaced by 
openings in the eighth abdominal segment, which, while slightly 
raised, force the larvae to lie parallel with the surface of the water. 
The long respiratory tubes of all other mosquitoes allow them, when 
breathing, to suspend themselves at an angle with the surface of the 
