140 MALARIA 



genus Hcemamceba the gametocyte has a general re- 

 semblance to the sporocyte before its nucleus divides 

 and it begins to form spores ; and it is impossible to 

 predict which amcebulae will become sporocytes and 

 which will become gametocytes. In Hcemomenas, 

 however, the gametocyte can be recognized at an 

 early stage. In this genus some of the amcebulae 

 become globular and ultimately form spores, whilst 

 others become elongated and slightly curved ; in fact, 

 they assume the shape of minute sausages. These are 

 the gametocytes. It is on this difference in shape that 

 Ross has founded his new genus for the parasite of the 

 aestivo-autumnal fever, all the essential characters of 

 which had, however, been previously recognized by 

 Italian and American observers. 



So long as the gametocytes remain in the blood of 

 the patient they undergo no further development ; on 

 being liberated from the cell into the fluid of the blood, 

 they degenerate and die ; but if they be removed, even 

 only on to a microscope-slide, they begin to develop. 

 They escape from the red corpuscle in which they 

 have hitherto been confined, and some of them the 

 male gametocytes are then seen suddenly to emit 

 long filaments (Fig. i, 10). These filaments can be 

 watched under a high power struggling violently to 

 free themselves from the cell which has given rise to 

 them. Ultimately they succeed, and breaking loose, 

 at once dart away amongst the corpuscles and other 

 debris on the slide. So long ago as 1880 Laveran had 

 seen these bodies, but until 1897 their nature was quite 

 misunderstood. This formation of the filaments or 

 flagella, sometimes called 'flagellation,' can only take 

 place at comparatively high temperatures. This has 

 an important relation to the seasonal variation in the 

 prevalence of the disease. 



Hitherto in this article we have only studied the 

 malarial parasite inside the body, with the exception 



