PARASITIC PROTOZOA JN RliLATlOJS TO THE WAR, 



309 



along with the drop of sahva that accompanies the inthrustinj>- 

 of the insect's proboscis. 



Three species of malarial parasites are usually recognized. 



Plasmodium vivax, the parasite of the so-called benign or 

 simple tertian malaria, causes intermittent attacks of fever every 

 48 hours. Its trophozoite, at first ring-like (Fig. 18), is fragile 

 or flimsy in appearance and amteboid in shape. When fully 

 grown, it causes enlargement of the host erythrocyte or red 

 blood-corpuscle, in which SchiitTner's dots may be seen (Fig. 

 19). It multiplies in the circulating blood, giving rise to 15 to 

 20 merozoites (Figs. 20, 21 ). It produces somewhat fine pigment 

 granules, and has spherical gametocytes or sexual forms. 



Plasmodium malaricc. the parasite of quartan malaria, is a 

 smaller organism, and does not cause enlargement of its host 

 corpuscle. It is somewhat compact with dense chromatin, and 

 forms dark, coarse pigment. It multiplies in the circulating 

 blood with the production of six to t>velve merozoites. Attacks 

 of fever occur every 72 hours. 



Fig. IS. 



Fig. 19. 



Fig. 20. 



Laverania malaricc or Plasmodium falciparum is the parasite 

 of malignant tertian, subtertian or pernicious malaria. It usually 

 multiplies asexually in the internal organs, forming up to 32 

 merozoites. It has characteristic crescent-shaped gametocytes or 

 sexual forms (Figs. 22, 23). Coarse stippling, known as 

 Maurer's dots, may occur in the host erythrocyte. This parasite 

 is more severe in its efifects than the other malaria-producing 

 organisms, and the blocking of the minute capillaries of the brain 

 bv a sudden increase in numbers of the parasite is responsible 



