53 



Chapter VI 



THE MALARIAL PARASITE 



Life History 



Among the groups into which the protozoa 

 are divided we find such well-known classes as 

 che Sarkodina, e.g., Amoeba Coli, the Mastigo- 

 phora, possessing flagella, e.g., Trypanosomes, and 

 the Sporozoa. It is these last that chiefly concern 

 us. The Sporozoa include such orders as the 

 Gregarines (e.g., monocystis in the testes of the 

 earth-worm) and the Haemosporidia (which in- 

 clude the malaria parasites of man, and blood 

 parasites of birds, etc.) There is a close relation- 

 ship between the coccidia and the haemosporidia 

 (malaria parasite), the delevopmental cycles of the 

 two being almost identical. The developmental 

 cycle in the blood (the febrile cycle) of the malaria 

 parasites was first demonstrated by Golgi, the 

 further cycle in the mosquito by Ross. The cycle 

 of Golgi is the asexual cycle, producing auto- 

 infection of the patient ; the cycle of Ross is the 

 sexual cycle, producing a new infection in a 

 healthy subject. 



The sexual cycle, it has been thought, com- 

 mences in the blood when the conditions are un- 

 favourable for the continuance of the asexual cycle, 

 and, in fact, has been taken as a sign that the 



