PLASMODIUM VIVAX 247 



of pigment are taken up by the leucocytes and deposited in the 

 spleen and bone marrow. 



The nucleus of the parasite may be seen if suitably strained. 

 The double or triple quartan is explained by the fact that there 

 are two or three groups of organisms that undergo sporogony at 

 periods separated from each by twenty-four hours. 



PLASMODIUM VIVAX (Grassi) 



The cause of tertian fever occurring in the spring. It differs 

 from the Plasmodium malaria because of shorter period (forty- 

 eight hours) consumed in schizogony (or sporulation), the much 

 greater activity of the amoeboid movement, and the affected cor- 

 puscles becoming enlarged; also by the fact that many of the 

 melanin-bearing stages are visible. The shizogony is rarely 

 apparent in the circulating blood, but in the spleen these stages 

 are easily seen. There are from 15 to 20 merozoites (segmented 

 bodies or spores) which are arranged in an irregular heap, but not 

 radially like wheel spokes. The merozoites are smaller than the 

 quartan variety and are more numero'us. The flagellated form 

 can but rarely be seen in the freshly drawn blood. If some blood, 

 containing the large extracorpuscular bodies, is put in a moist 

 chamber, they throw out flagella. These flagella are really 

 micro gametes and are sexually active. The extracorpuscular 

 bodies are partly macro gametes , and if they become flagellated 

 they are called polymites, and are the micro gametocytes. The 

 merozoites, or spores, finally burst forth from the erythrocytes, 

 starting again another cycle (attended with a paroxysm of fever) . 

 These spores appear in the freshly invaded corpuscles as hyaline 

 bodies with slight movement. As they grow in size, pigment 

 appears in the protoplasm. Certain of these do not break up 

 into merozoites, or spores, but become extracellular bodies 

 gametocytes of male or female character. There may be two 

 infections in which schizogony occurs every other day in alternate 

 days, 12121212. 



