MALARIA PARASITE 323 



commonest sites of melanotic sarcoma is in the choroid 

 coat of the eye, where the cells are normally pigmented. , \ 



The pigment of these cells is called melanin, and it 

 is supposed to be derived from hemoglobin. 



Professor Ronald Ross suggested that some experi- 

 ments might be made with auxetics on the malaria 

 parasite, and in one case a "crescent" was apparently 

 made to flagellate prematurely with a jelly containing 

 azur dye, extract, and atropine, although repetitions 

 of the same experiment were not successful. Still, 

 the consideration of the life-history of the malaria 

 parasite has been as it turns out germane to our 

 researches. The parasite enters the body from the 

 mosquito as a minute unpigmented amrebula, which 

 straightway enters a red blood-corpuscle. While in 

 the red cell it gradually becomes pigmented, and it 

 proliferates by exporulation. The daughter parasites 

 have no pigment until they enter fresh red cells, 

 when in their turn they become pigmented and ulti- 

 mately proliferate again. 



There is the so-called sexual form of the cycle, 

 however, which probably does not proliferate within 

 the body. The crescent or gametocyte only pro- 

 liferates after the blood containing it has been shed. 

 The crescent is also deeply pigmented; and it is a 

 most interesting point to remember that when the 

 crescent stage of the parasite is reached, the red cell 

 appears to be depleted of haemoglobin, and merely 

 surrounds the parasite as an empty cell. The parasite, 

 when it has reached the crescent stage, has apparently 



