MALARIA 639 



distinguish from the schizonts, in the benign tertian and 

 quartan fevers. 



Various suggestions were made in the past as to the 

 nature of these flagellated bodies. Through the 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 

 higher animals. The female cells or female gametocytes 

 or gametes are non-flagellated, and are fertilised by the 

 entrance of one of the flagella of a male gametocyte. This 

 fertilisation takes place in the stomach (middle intestine) of 

 certain species of mosquito, and after fertilisation a series of 

 changes ensues resulting in the formation of spore-like 

 bodies, which are injected when the insect bites its victim, 

 and thus the infection of fresh individuals with the malaria 

 parasite takes place. The first demonstration of the nature 

 of " flagellated bodies " was given by Opie and MacCallum 

 on the Halter idium, a parasite of pigeons, and this forms 

 a good example of the value of abstract research to 

 practical medicine (see p. 653). Ross also followed the 

 development of the malaria-like Proteosoma of sparrows, 

 etc., in the mosquito, Culex fatigans. The development 

 of the malaria parasite of man in the mosquito is as follows, 

 according to Ross and Fielding-Quid. 1 It is not known 

 what determines whether an amcebula will become a 

 sporocyte or a gametocyte. When the sexual cells or 

 " gametocytes " are ingested with the blood by the mos- 

 quito, they pass into the middle intestine. Within a few 

 minutes the corpuscles enclosing them break down, the 

 parasites are set free, and quickly become spherical or 

 ovoid (Fig. 58, c, e, and/). One or two spherical granules 



1 Thompson Yates Laboratories Report, vol. iii, pt. ii, p. 183, 



