572 
DIPTERA. 
the blood-corpuscles, whose interior they slowly absorb, and when full 
grown they either break up again to form a fresh lot of minute bodies 
which will enter a fresh lot of blood-corpuscles (this breaking up being 
the cause of the shivering or 44 rigor ” stage of the disease), or else they 
develop into crescents which float about free in the blood: these 
crescents may of course be sucked up by another mosquito and the cycle 
carried through again. Thus we see that the parasite multiplies in two 
ivays; sexually in the mosquito, and asexually (by simply splitting up 
into small fragments) in our blood. 
It is not all mosquitos which are capable of harbouring the malaria 
parasite and allowing it to develop in their stomachs, but only some of 
those belonging to the Anophelince. Manson ( 44 Tropical Diseases ”) 
enumerates eleven Indian species as having (up to 1907) been shown to 
be probable carriers of the parasite, and these belong to the genera 
Myzomyia, Pyretophorus , Myzorhynchus, and Nyssorhynchus, all of 
which are really sub-genera of the old genus 44 AnophelesMyzomyia 
Rossii , the commonest Indian Anopheline, but not a malaria-carrier, 
is figured on PI. LX, fig. 4, where are also shown two other mosquitos 
both important Culicines. One is Stegomyia fasciata , which with S. 
scutellaris is not uncommon in India, the latter species being abundant. 
S. fasciata is the recognised transmitter of yellow fever, and is 
suspected with regard to several diseases, while Culex fatigans (PI. LX, 
fig. 6) is the commonest Indian brown Culicine mosquito, and is 
known to carry the parasite which causes elephantiasis {filariasis) so 
prevalent in Southern India. 
It is clear that to avoid whenever possible the bites of all mosquitos 
is a sensible and obvious precaution. It is not only unpleasant but 
stupid to sleep without a mosquito-net in malarial districts where mos¬ 
quitos are present. A net with a hole in it is useless. When no mos¬ 
quito-net is available, as in railway carriages, a small quantity of Citro- 
nella (Lemon-grass) oil rubbed on the exposed parts of the body is 
effective for four or five hours unless the user is perspiring freely, when 
it more quickly loses its efficacy. Turpentine or kerosene ointment 
are effective but unpleasant. 
For destroying mosquitos, the remedy usually advocated is the 
application of kerosene to the surface of the water in which they 
