Pathogenesis 539 



ment granules are more widely scattered throughout the sub- 

 stance. The crescents are most numerous after the fever 

 has lasted for some time or in recurrences of the fever. 



The fever in this form of malarial infection may be inter- 

 mittent with daily quotidian paroxysms, or with irregu- 

 lar paroxysms, or the fever may be remittent. The infec- 

 tion is sometimes mild, but may be so severe as to be rapidly 

 fatal. In such cases the number of parasites is enormous, 

 the cerebral capillaries become filled with them, and coma 

 quickly comes on and is soon followed by death. Such 

 cases are described as " congestive chills " or " algid " 

 cases. 



Cultivation of the Parasites. The parasites have not 

 been successfully cultivated, though they have been kept 

 alive for some time in blood, prevented from coagulation, by 

 Bass. 



Animal Inoculation. The human malarial parasites can- 

 not be successfully transmitted by experimental inoculation 

 to any of the lower animals. 



Human Inoculation. The blood of one human being con- 

 taining schizonts, when experimentally introduced into an- 

 other human being in doses of i to 1.5 c.c. transmits the dis- 

 ease. When thus transmitted, an incubation period of 

 from seven to fourteen days intervenes before the disease, 

 which is of the same type as that from which the blood was 

 taken, makes its appearance. 



Pathogenesis. The pathogenic effects wrought by the 

 malarial parasite are imperfectly understood. The syn- 

 chrony of the segmentation of the parasite and the occur- 

 rence of the paroxysms seems to indicate that a toxic sub- 

 stance saturates and disturbs the economy at that time. 

 Whether it be an endotoxin liberated by the dividing parasite 

 is not, however, known. 



The anemia that follows infection can be referred to the 

 destruction of the red blood-corpuscles by the parasites which 

 feed upon them and transform the hemoglobin into melanin 

 (?). When great numbers of the parasites are present the 

 destruction is enormous, and the number of corpuscles and 

 the quantity of hemoglobin in the blood sink far below the 

 normal. Leukopenia instead of leukocytosis is the rule, and 

 while the leukocytes have an appetite for the spores of the 

 parasites and often phagocyte and destroy them, their activ- 



