Filariasis and Mosquitoes 



179 



the United States, and as far south as Brisbane in AustraHa." In 

 some sections, ftdly 50 per cent of the natives are infested. Labredo 

 (19 10) found 17.82 per cent infestation in Havana. 



The larval forms of Filaria bancrofti were first discovered in 1863, 

 by Demarquay, in a case of chylous dropsy. They were subse- 

 quently noted vmder similar conditions, by several workers, and by 

 Wticherer in the urine of twenty-eight cases of tropical chyluria, 

 but in 1872 Lewis foimd that the blood, of man was the normal 

 habitat, and gave them the name Filaria sanguinis hominis. The 



adult worm was found in 1876 

 by Bancroft, and in 1877, 

 Cobboldgave it th&n&m&Filaria 

 bancrofti. It has since been 

 found repeatedly in various parts 

 of the lymphatic system, and its 

 life-history has been the subject 

 of detailed studies by Manson 

 (1884), Bancroft (1899), Low 

 (1900), Grassi and N06 (1900), 

 Noe (1901) andFiillebom(i9io). 

 The larvae, as they exist in 

 the circulating blood, exhibit a 

 very active wriggling movement, 

 without material progression. 

 They may exist in enormous 

 numbers, as many as five or 

 six hundred swarming in a 

 single drop of blood. This is the more surprising when we con- 

 sider that they measure about 3oo[ji. x 8[a, that is, their width is 

 equal to the diameter of the red blood corpuscle of their host and 

 their length over thirty-seven times as great. 



Their organs are very immature and the structure obsctire. When 

 they have quieted down somewhat in a preparation it may be seen 

 that at the head end there is a six-lipped and very delicate prepuce, 

 enclosing a short "fang" which may be suddenly exserted and 

 retracted. Completely enclosing the larva is a delicate sheath, 

 which is considerably longer than the worm itself. To enter into 

 further details of anatomy is beyond the scope of this discussion 

 and readers interested are referred to the work of Manson and of 

 FuUebom. 



119. 



Elephantiasis in Man. From "New 

 Sydenham Society's Atlas." 



