MICRO-ORGANISMS IN VARIOUS DISEASES. 199 



(d) Exit : In the blood solely through bites of mos- 



quitoes. 



(e) Contracted: By being bitten by that species of 



mosquito (Anopheles) which acts as host 

 for the parasite. 



(f) Disinfection: Consists in the destruction of mos- 



quitoes by an insecticide in the bed-room 

 of the sick. Pyrethrum, two pounds to each 

 one thousand cubic feet. Sulphur, one 

 pound to each two thousand cubic feet. 

 Where sulphur used, two hours' exposure 

 sufficient, and moisture (which decolorizes 

 and destroys fabrics) not necessary. As 

 pyrethrum only stuns the knats they must 

 be gathered up and burned after fumigat- 

 ing. 



(g) Prophylaxis : Where malaria is prevalent, screen 



rooms and houses with fine mesh screens 

 to keep mosquitoes out; chief danger is at 

 night, since anopheles is nocturnal in 

 its habits. Anopheles breeds in shallow 

 puddles and ditches, in which places the 

 young can be destroyed by sprinkling sur- 

 face of water with coal-oil about every two 

 weeks. Two grains of quinine three times 

 daily is also a wise precaution. 



Measles. 



(a) Cause: Unknown. 



