524 . MALARIAL FEVER. 



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. 



2. A non-pigmented quotidian parasite has been differ- 

 entiated and described by Marchiafava, which differs from 

 the previous only in the absence of pigment. 



3. 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, 

 may be found in the brain and internal organs. In some 

 fatal cases with coma, the cerebral capillaries may appear 

 to be almost filled with them. 



Irregular types of fever, sometimes of a continued 

 character, may be produced by infection with different 

 generations of the same variety of parasite, or by different 

 varieties (mixed infections). In the various tropical 

 malarial fevers it is quite possible that there are still 

 other varieties of parasites whose characters have not yet 

 been worked out. 



Relations to the Disease. Though the malarial para- 

 sites have in no form been cultivated outside the body, 

 the evidence that they are the cause of the disease amounts 

 to a practical certainty. They are always present in the 

 disease, and have been found in no condition apart from 

 malaria. Their cycle of development also corresponds in 

 a remarkable manner with .the course of the fever, each 

 febrile attack being accompanied by the appearance of a 

 new generation of parasites in the blood. In all probability 



