THE MALARIA PARASITE 



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are actively motile and disturb the corpuscles, but the 

 body itself does not move much. Frequently one or 

 more of the flagella break away and swim free, remaining 

 active for several hours. The flagellated bodies are never 

 seen in the freshly drawn blood, and Ross has found that 

 flagellation does not occur if the finger be pricked through 

 a spot of vaseline, the blood remaining covered with the 



FIG. 59. Development of the malaria parasite in the mosquito. 

 a, b, and c, the male gametocyte ; d, e, and /, the female 

 gametocyte ; /, fertilisation of the female gametocyte by a 

 microgamete. (After Ross and Fielding- Ould.) 



film of grease. Careful observation has shown that the 

 flagellated bodies develop from " crescents " in subtertian 

 malaria, and from special rounded parasites, difficult to 

 distinguish from the schizonts, in the benign tertian and 

 quartan fevers. 



Various theories were held in the past as to the nature 

 of these flagellated bodies. Through the brilliant researches 

 of Ross, which have been confirmed and extended by 

 observers in all parts of the world, it is now known that 

 these cells are sexual elements. The flagellated body 

 represents the male cell or " male gametocyte," the flagella 

 (" gametes ") being analogous to the spermatozoa of 



