THE THREE HUMAN PARASITES 595 



in si/A- or appearance, and the pigment within the parasite is in 

 the form of coarse granules, of dark brown or almost black 

 colour. The fully developed schizont has a " daisy-head " 

 appearance, dividing by regular radial segmentation into from 

 >ix to twelve merozoites, which, on becoming free, are rounded 

 in form. 



2. The Para*<f< <>,' Mild Tertian Fever. The cycle of de- 

 velopment is completed in forty-eight hours, though a quotidian 

 type of fever may be produced by double infection. The 

 amcebuki' have a less refractile margin than in the quartan type, 

 and arc thus less easily distinguished in the fresh blood; the 

 anueboid movements are, however, much more active, while 

 longer and more slender processes are given off. The infected 

 corpuscles become swollen and pale, and may show deeply 

 stained points by the Romano wsky method " Schiiffner's dots." 

 The pigment within the parasite is fine and of yellowish-brown 

 tint. The mature schizont is rather larger than in the 

 quartan, has a rosette appearance, and gives rise to from fifteen 

 to twenty merozoites, though sometimes even more occur; these 

 have a somewhat oval shape. 



In both the quartan and tertian fevers all the stages of 

 development can be readily observed in the peripheral blood. 

 The gametocytes have a rounded form as described above. ' 



3. The Parasite of Malignant or JKstivo-autumnal Fever or 

 Ti-'ij-ii-nl Mnlnriii. The cycle in the human subject probably 

 occupies forty- eight hours, though this cannot be definitely stated 

 in l>e always the case (vide mpra). The amcebulae in the red 

 corpuscles are of small size, and their amoeboid movements are 

 very active ; they often, however, pass into the quiescent ring 

 form (Fig. 163). The pigment granules, even in the larger 

 forms, are few in number and very fine ; the infected red 

 corpuscles have a tendency to shrivel and assume a deeper or 

 coppery tint, sometimes they are swollen and decolorised. The 

 fully <leveloj>ed schizont usually occupies less than half the red 

 corpuscle, and gives rise to from six to twenty merozoites, some- 

 what irregularly arranged and of minute size. Schizogony 

 takes place almost exclusively in the internal organs, spleen, 

 etc., so that, as a rule, no sporocytes can be found in the blood 

 taken in the usual way. The proportion of red corpuscles infected 

 by the amcebula? is also much larger in the internal organs. The 

 gametocytes have the crescentic form, as already described. 



Cases of infection with the malignant parasite sometimes 

 assume a pernicious character, and then the number of organisms 

 in the interior of the body may be enormous. In certain fatal 



