Filariasis and Mosquitoes 
179 
the United States, and as far south as Brisbane in Australia.” In 
some sections, fully 50 per cent of the natives are infested. Labredo 
(1910) 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 under similar conditions, by several workers, and by 
Wiicherer in the urine of twenty-eight cases of tropical chyluria, 
but in 1872 Lewis found 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 the name 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 Noe (1900), 
Noe (1901) and Fullebom (1910). 
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 300;./. x 8(jl, 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 obscure. 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 
Fullebom. 
119. Elephantiasis in Man. From “New 
Sydenham Society’s Atlas.” 
