482 MALARIAL FEVER. 



resulting in the formation of fifteen to twenty round spores, 

 takes place by means of a rosette or rather a sunflower 

 formation, the lines of segmentation being at the periphery, 

 and a portion remaining around the central collection of 

 pigment (vide Figs. 102-104). 



(b) The more severe forms (sestivo-autumnal fevers). 

 In these the crescent forms are found (Fig. 106). 



1. Quotidian. This is the form most commonly 

 assumed by malarial fever in the tropics. The parasite 

 passes through its cycle of development in twenty-four 

 hours. Within the red corpuscles the parasite is of small 

 size, and even in its adult condition, immediately before 

 sporulation, does not usually occupy more than a third of 

 the corpuscle. The amoeboid forms often pass into the 

 " ring-form " described above. In their course of develop- 

 ment they acquire very fine dust-like pigment, and in the 

 adult quiescent form the pigment becomes collected into a 

 small dark body. The spores (usually six to eight) are 

 formed by irregular segmentation, and are very minute ; the 

 process takes place almost exclusively in internal organs 

 spleen, etc., so that as a rule no sporulating forms can be 

 found in the blood taken in the usual way. 



A non-pigmented quotidian parasite has been differ- 

 entiated and described by Marchiafava, which differs from 

 the previous only in the absence of pigment. 



2. Malignant Tertian or Summer-autumn Tertian (Mar- 

 chiafava and Bignami). The parasite closely resembles 

 that of the quotidian. Its cycle of development, however, 

 occupies forty-eight hours, and the young parasites may be 

 without pigment for twenty-four hours. The amoeboid 

 activity is maintained even in the adult pigmented forms. 

 There are also some minor points of difference. In this 

 variety also ring-forms occur. 



In these three varieties the red corpuscles invaded by 

 the parasite have a certain tendency to shrivel and become 

 of deeper or coppery tint. The disease sometimes assumes 

 a malignant character, and when a fatal result occurs, large 

 numbers of parasites, many in process of segmentation, 



