LIFJE-HISTORY OF THE PARASITES OF MALARIA. 573 



granules, which are called the melanin or malarial pigment. 

 These granules lie in the bioplasm of the parasite surrounding 

 the nucleus. After an interval of from one to several days 

 (according to the species concerned) the amoebulggj still 

 contained within the corpuscle, reach maturity, and become 

 either (a) sporocytes or (&) gametocytes. In the case of the 

 amcebulee which become sporocytes the nucleus divides into 

 a number of segments (varying according to the species). 

 Each segment of the nucleus surrounds itself with a portion 

 of the bioplasm, and becomes a spore — the process being 

 obviously one of simple asexual propagation. Finally the 

 corpuscle which contains the parasite, and which has now 

 been almost entirely destroyed by it, bursts and liberates the 

 spores, allowing them and a small nucleus de reliquat, 

 consisting chiefly of the melanin, to fall into the liquor 

 sanguinis. The melanin is taken up by the phagocytes of 

 the host, while the spores attach themselves to fresh red 

 corpuscles, become amcebulas in their turn, and thus continue 

 the life of the organisms indefinitely within the vertebrate 

 hosts. 



In the case of the amoebul^ which become gametocytes 

 the history is quite different. It is not yet definitely known 

 what determines a given amoebula to become either a sporo- 

 cyte or a gametocyte, but the fact must be accepted. In 

 the gametocytes the nucleus does not divide as in the case 

 of the sporocytes — the parasite reaches maturity without 

 showing any sign of spore-formation. In the majority of 

 species (genus HEemamceba) the gametocyte has a general 

 form similar to that of the sporocyte before the spores are 

 produced; but in one species (genus Hsemomenas) the 

 gametocyte has a special (cresceutic) shape, which is recog- 

 nisable at an early stage in its career. As their name indi- 

 cates, the gametocytes are sexual forms, male and female. 

 They possess no function within the vertebrate host, but are 

 meant to continue the life of the organisms within a second 

 host — a suctorial insect. 



When the gametocytes are drawn into the stomach cavity 



