106 PLASMODIUM MALARIA 



which the flagella are derived appear to undergo 

 degeneration or absorption. 



These flagellated bodies are derived either from 

 the crescent bodies, or, in those varieties of the 

 parasite which do not form crescents, from extra- 

 corpuscular plasmodia resembling the fully developed 

 form just prior to sporulation. The crescent becomes 

 a sphere with central pigment, this sphere becomes 

 agitated with movements of increasing violence, 

 and, finally, the flagella are shot out from the 

 periphery. Similar movements affect the flagella- 

 producing body which is not derived from the 

 crescent. 



These flagella are regarded by Man son as the first 

 phase of extra- corporeal life. It has been shown by 

 Ross that the transformation and ex- flagellation 

 take place most fully in the stomach of certain 

 varieties of mosquito. On the analogy of observa- 

 tions by MacCullum on an allied parasite in crows, 

 these flagella or flagellated spores impregnate a 

 non-flagellated body, and the resulting organism is 

 probably found as a pigmented cell in the stomach 

 wall of the mosquito. The mosquito thus plays 

 the part of secondary host, and man is infected by 

 water or dust which has been itself infected by 

 mosquitos. The varieties of malarial parasites at 



