656 INFECTION AND IMMUNITY. 



segmentation At the end of thirty-six hours they have increased 

 H ce?iL noticeably in size and their ameboid motion is 

 less. Shortly before the next attack i. e., from 

 forty-six to forty-eight hours after the preceding 

 one the pigment assembles into one or two groups 

 in the center of the parasite and clear hyaline 

 points begin to appear. These are the young endo- 

 cellular parasites which are formed by division of 

 the nucleus of the mother cell. They gradually 

 increase in size and number, and as the red cor- 

 puscles disintegrate they are discharged, from fif- 

 teen to twenty-five in number, as young parasites. 

 This completes the cycle, an asexual cycle, which 

 has lasted forty-eight hours, and the young forms 

 then begin a new cycle after penetrating other red 

 corpuscles. The mother cell is called the sporo- 

 cyte and its offspring are merozoites, and the proc- 

 ess of division schizogony. 



sexnai In addition to the asexual cell just described, 

 two sexual cells, a male and a female, grow to 

 adult size in the erythrocytes, acquire pigment and 

 eventually become free. They differ from the 

 asexual cell in that the pigment continues to be 

 uniformly distributed, and neither gives rise to 

 young parasites by division. The male cell (micro- 

 gametocyte, 8-9 microns) has a clear protoplasm 

 and is smaller than the female (macrogamete, 

 10-14 microns) ; the female has a granular proto- 

 plasm. There are many more male than female 

 cells. They undergo no further development in 

 the body of man, and in order that the sexual pro- 

 cess be completed the two cells must first gain 

 entrance into the stomach of the female anopheles 

 mosquito. 



