MALARIAL PARASITE. 659 



At this time a fine line drawn across the concavity 

 of the parasite represents the margin of the ery- 

 throcyte. This form is only temporary, however; 

 they subsequently assume first a spindle and then 

 a spherical form. As in the other parasites, the 

 male cell is rather clear and the female granular. 

 When mounted in a hanging drop the male cell 

 liberates flagella, which penetrate the female cell. 

 This does not occur in the human body. In this 

 respect, and also in the completion of the sexual 

 cycle in the body of the mosquito, they resemble the 

 other two parasites. 



The parasites of tertian and quartan fevers un- 

 dergo division while they are in the circulating 

 blood, and when peripheral blood is examined at the 

 end of the afebrile stage the young cells may be 

 found extracellular. This is not the case, how- 

 ever, in the aestivo-autumnal fever. In this in- 

 stance, for unknown reasons, the adult cells with- 

 draw to the internal organs, especially the spleen, 

 bone-marrow and brain, where division takes place 

 in the minute vessels. Hence if the peripheral 

 blood is examined preceding and during the febrile 

 stage few or no dividing cells or young parasites 

 are seen. 



Following inoculation by an infected mosquito, incubation 

 ten to twelve days are required for the onset of a 

 paroxysm. In rare instances the incubation period 

 may be as short as five to six days. This probably 

 depends to some extent on the number of organisms 

 inoculated. Malarial infection of the mosquito 

 is not transmitted to the offspring the latter, 1 

 hence the bites of young mosquitos do not convey 



1. This is questioned by Schaudinn. 



