THE PROTOZOA AS PARASITES OF MAN 



157 



in which the English observer Ross played a great part — has 

 made us less helpless to avert its ravages. The measures 

 which are taken to that end are threefold : (1) the destruc- 

 tion of the mosquito, by such measures as have been 



Anopheles 



Culex 



FIG. 97. — A comparison of the various stages in the life-history of a 

 mosquito (left) with those of a gnat (right). — From Shipley. 



Note how the larvae and pupae hang from the surface film of the water (represented 

 by a thin line). The organs by which they are suspended contain air tubes, and 

 if these be prevented by a film of paraffin from reaching the air the insect is 

 drowned. 



e. t two views of an egg, magnified. 



mentioned; (2) the use of quinine to overcome the 

 parasite in the blood and thus destroy the supply of it as 

 well as benefiting the individual patient ; (3) the separation 

 of European dwellings from those of the natives. 



