538 Malaria 



the " large ring " stage is reached the parasites begin to 

 disappear from the peripheral blood to complete their growth 

 and undergo meroblast formation in the capillaries of the 

 spleen, the brain, and the bone-marrow. Here the full- 

 grown parasites meroblasts appear as irregular disks, 

 resembling those of the quartan parasite, but smaller in size. 

 The pigment is gathered toward the center in a little mass, 

 and eight to twenty-five merozoits are formed in a morula 

 or mulberry-like mass similar to those of the tertian para- 

 site. Two or three parasites to the corpuscle are frequent. 

 They are actively ameboid, do not mature simultaneously, 

 and hence there are no regularly occurring paroxysms. The 





Fig. 1 80. Fig. 181. 



Figs. 1 80, 181. Gametocytes of plasmodium falciparum: 91, The mi- 

 crogametocyte; 92, the macrogametocyte (Kolle and Wassermann). 



duration of the asexual cycle is from twenty-four to forty- 

 eight hours. 



The gametocytes are striking and characteristic ovoid and 

 crescentic bodies crescents i J times the diameter of a red 

 blood-corpuscle in length, and about half the diameter of the 

 corpuscle in breadth. The ends color more intensely with 

 methylene-blue than the middle portion, and the bacillary 

 pigment granules are collected toward the centers. The 

 longer and more slender crescents are usually bent, and the 

 relic of the corpuscle in which they have formed can often 

 be seen forming a line connecting the ends on the concave 

 side. These are the microgametocytes or male elements. 

 The macrogametocytes are broader, not curved, and some- 

 times are ovoidal or prolate spheroidal in shape. The pig- 



