4 22 



SPECIFIC MICRO-ORGANISMS 



marrow and 



which become crescentic early in their development and differen- 

 tiated into deeply staining macrogametocytes and pale-staining 

 microgametocytes. These are produced especially in the bone 

 circulate in the peripheral blood. Further 

 development takes place when the blood 

 is taken into the stomach of a mosquito 

 of the genus Anopheles. Here the mi- 

 crogametes, slender actively motile 

 threads, are given off by the microgam- 

 etocyte and fertilize the macrogam- 

 etes, producing ookinetes which ac- 

 tively penetrate the epithelium. In the 

 wall of the mosquito's stomach each 

 ookinete gives rise to a rapidly growing 



FIG. 195. Digestive tract 

 of Anopheles, the stomach of 

 which is covered with numer- 

 ous oocysts of PL falciparum, 

 -viewed from the left side, c, 

 Cloaca;s, stomach; o, oocysts 

 of Plasmodium; mt, malpigh- 

 ian tubules; sb, sucking blad- 

 ders; sg, salivary gland. 

 (From Doflein, modified after 

 Ross and Grassi.) 



FIG. 196. Plasmodium falciparum. 

 Ripe sporozoits arranged about residual 

 bodies within the oocyst, cut in various 

 directions (7 to 8 days after infection of 

 the mosquito). (From Doflein after 

 Grassi.} 



