PLASMODIUM VIVAX 165 



period the first brownish melanin granule appears. From this time 

 the activity and number of the pigment granules increase with con- 

 tinuous growth. When the parasite has grown to about one-third 

 the diameter of the erythrocyte the latter shows characteristic red 

 Schuffner's dots or " fine stippling/' after staining with Romanowsky's 

 solution. Later, after about twenty-four hours, the blood corpuscles 

 begin to grow pale, then to increase in size, and after thirty-six hours, 

 that is, about twelve hours before the next attack of fever, schizogony 

 of the parasite is initiated by the division of the nucleus. The parasite 

 at this time occupies half to two-thirds of the enlarged blood cor- 

 puscle. The daughter nuclei continue dividing until sixteen, and 

 occasionally twenty-four, daughter nuclei are produced. The pigment 

 which, up till now lies nearer the periphery, moves to the middle, 

 while the nuclei lie nearer the surface. 



FIG. 85. Development of the tertian parasite in the red blood corpuscles of man'; 

 on the right a " Polymitus." (After Mannaberg.) See also fig. 80, j 7. 



Around each nucleus a portion of cytoplasm collects and thus 

 young merozoites are produced. These separate from each other and 

 from the little residual masses : which contain the melanin and pass 

 from the blood corpuscles, which now can hardly be recognized, to 

 the blood plasma, where they soon attack new erythrocytes. 



The migration of the merozoites initiates a new attack of fever 

 and two groups of tertian parasites in the blood, differing in develop- 

 ment by about twenty-four hours, are the conditions for febris tertiana 

 duplex. 



After a lengthy duration of fever the gametocytes (figs. 80, 9 12) 

 appear. They are uninucleate. The microgametocytes are about the 

 size of fully developed schizonts, the macrogametocytes are somewhat 

 larger. Their further development takes place in Anophelines. 



1 The pigment masses (melanin or hsemozoin) are taken up by the leucocytes, particularly 

 the mononuclear ones, and are carried especially to the spleen, and also to the liver and the 

 bone-marrow. From this circumstance arises the well-known pigmentation of the spleen in 

 persons who have suffered from malaria. 



