484 THE CONTROL OF MALARIA AND YELLOW FEVER 



wall of the stomach and form cysts on the outer stomach wall. In 

 these cysts, the parasites break into thousands of needle-shaped 



spores, which finally 

 escape from the cysts, 

 enter the blood of the 

 mosquito, make their 

 way around the body, 

 and especially infect 

 the salivary glands. 

 When the mosquito 

 now bites another per- 

 son, malarial organ- 

 isms enter the victim's 

 body with the mos- 

 quito's saliva. The 

 malarial parasite 

 seems to produce no 

 ill effects on the mos- 

 quito. In the human 

 host the malarial para- 

 site reproduces asexu- 

 ally and differentiates 

 into sex cells which 

 may be called a sexual 

 phase ; in the body of 

 the mosquito it repro- 

 duces both sexually 

 and asexually. 



Nature. The poison produced by the germs causes a marked 

 chill, followed by fever, then profuse perspiration, and a fall of 

 temperature. This is followed by a period of well-being until the 

 onset of the next chill, usually 48 hours later in our type of 

 malaria.*- Destruction of the red corpuscles may cause anaemia 



The malarial parasite undergoes a cycle in its life history 

 from mosquito to man and back again to the mosquito. 

 Trace the complete history of the organism in the diagram 

 above. 



