VARIETIES OF THE MALARIAL PARASITE 531 



fully developed schizont has a "daisy-head" appearance, 

 dividing by regular radial segmentation into six to twelve 

 merozoites which, on becoming free, are rounded in form. 



2. The Parasite of Mild Tertian Fever. The cycle of develop- 

 ment is completed in forty-eight hours, though a quotidian type 

 of fever may be produced by double infection. The amoebulae 

 have a less refractile margin than in the quartan type, and are 

 thus less easily distinguished in the fresh blood ; the amoeboid 

 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 Romanowsky method " Schiiffner's dots." The pig- 

 ment 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 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. 



3. The Parasite of Malignant or JEstivo-autumnal Fever, or 

 Tropical Malaria. The cycle in the human subject probably 

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

 to be always the case (vide supra). The amoabulse 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. 160). 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. The fully developed schizont occupies less than 

 half the red corpuscle, and gives rise to usually from six to 

 twelve merozoites, somewhat 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 amoebulae is also much larger 

 in the internal organs. The gametes 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 

 cases with coma the cerebral capillaries appear to be almost 

 filled with them, many parasites being in process of sporulation ; 

 and in so-called algid cases, characterised by great collapse, a 

 similar condition has been found in the capillaries of the 



