PLASMODIUM M ALARMS. 633 



their presence alone the diagnosis must often rest: (1) 

 In severe acute cases after the administration of much 

 quinine; (2) in remittent malarial fevers; and (3) in 

 chronic malarial fever and cachexia. They persist in 

 the blood long after all traces of parasites have dis- 

 appeared. The identification of free malarial pigment 

 is usually hazardous, and the diagnosis of malaria 

 should never be based on its presence alone (Ewing). 



Inoculation Experiments. Malarial infection can be 

 transmitted directly from man to man by subcutaneous 

 or intravenous inoculation of malarial blood. This was 

 shown first by Gerhardt in 1884. Later experiments, 

 chiefly by Italians observers, have confirmed Gerhardt 7 s 

 investigations, and almost in every instance the variety 

 of organism introduced has been reproduced. It has 

 also been experimentally shown that the ague paroxysm 

 is associated with the segmentation of enormous groups 

 of intracorpuscular amoeba?, the symptoms being prob- 

 ably due, as Bacelli suggests, to toxins liberated during 

 sporulation or to substances set free in the blood by 

 the rapid destruction of a large number of its corpuscles. 

 The period of incubation is from eleven to twelve days 

 in the regular intermittents and from two to five days 

 in the irregular autumnal fever. 



Active phagocytosis goes on in all forms of malarial 

 infection, but its true significance is still undetermined. 

 That many parasites are devoured by the leucocytes, 

 especially in the spleen, is certain. This apparently 

 takes place during or after sporulation. But sponta- 

 neous recovery may also be due to the death of the 

 plasmodia. It is not improbable, however, that the 

 phagocytes contribute to the process of recovery, even 

 if they are not the chief factors in it. 



