PROTOZOA IN THE CIRCULATORY SYSTEM 91 



These are coarse granules and of much darker color than 

 those of P. vivax. For about 24 hours, the growth of the 

 schizonts is relatively slow; now may measure about one- 

 half the diameter of the host cell which remains un- 

 changed, except sometimes they may be slightly smaller 

 and stain more deeply than uninfected ones. As the growth 

 continues, the schizonts tend to be stretched into band- 

 form across the erythrocytes. The younger schizonts are 

 narrow bands (Fig. 23, ^), while the older are broad bands 

 (Fig. 23, ^-^). This "band-form" is one of the characteristics 

 of this species and possesses a high diagnostic value. Dots 

 comparable with Schiiffner's dots do not occur ordinarily 

 in this species. 



3. Mature schizonts and schizogony. In about 48 hours, 

 the schizont nearly fills the erythrocyte. It is rounded and 

 haemozoin granules first scattered, begin to collect into a 

 mass. At about this time, the nucleus divides into 6-12 

 daughter nuclei by repeated binary fission (Fig. 23, 6-8). 

 These nuclei are often arranged in a circle, and soon a 

 ring of 6-12 merozoites are formed with the pigment mass 

 in the center. These merozoites (Fig. 23, 9, 10) appear to be 

 the largest of the three species. A little before the attack of 

 fever, the infected erythrocytes rupture and set the mero- 

 zoites free in the blood plasma. 



Gametocytes 



The development of gametocytes takes place in the 

 peripheral blood, but it is difficult to distinguish them from 

 growing schizonts, since the latter are more or less com- 

 pact and rounded in this species. The mature gametoc\ tes 

 are spherical and fill the erythrocytes which are normal in 



