SPOROZbA 



771 



band widens until the parasite is nearly square and the hemozoin ac- 

 cumulates toward the center. Segmentation gives rise to almost sym- 

 metrical ' ' daisy ' ' forms, showing six to eight or, rarely, fourteen mero- 

 zoites. Parasites of different ages may be found, as in tertian, and 

 it is characteristic of quartan fever that examples of all stages of 

 the life cycle may be found at the proper time in the peripheral cir- 

 culation. Gametes differ from tertian mainly in size, since they are 

 never larger than the normal erythrocyte until after the latter has 

 ruptured, but when free in the plasma it is practically impossible to 

 distinguish them from tertians. 



; 



FIG. 191. PLASMODIUM MALARIA. 

 (Army Med. School Collection, Wash- 

 ington, D. C.) 



FIG. 192. PLASMODIUM FALCIPARUM. 

 (X 1500.) (Army Med. School Col- 

 lection, Washington, D. C.) 



Plasmodium falciparum. The parasite of aBstivo-autumnal fever, 

 Plasmodium falciparum, differs considerably from the two forms al- 

 ready described; the life cycle varies between twenty-four and forty- 

 eight hours, and, at least in new infections, only ring forms are 

 found in the peripheral blood, although at a later stage crescentic 

 gametes may be present. The youngest asstivo-autumnal rings, found 

 at the height of the fever, are more delicate than the young tertians. 

 As the temperature falls the rings increase in size, but without 

 change of form ; the growth is not uniform, but occurs as a thick cres- 

 centic swelling on the convex surface of the ring, and occasionally 

 more than one such swelling is present. The large a?stivo-autumnal 

 ring, found after the febrile paroxysm has passed, occupies one-third 

 to one-half the red cell, which is never swollen nor stippled, as in ter- 

 tian, and the parasite is never band-like, as in quartan. Segmenting 



