770 PATHOGENIC PROTOZOA 



ment with the schizonts. They are now called gametes and after the 

 disease has lasted some time are found in films made at all stages of 

 the fever; that is, they are incapable of further development un- 

 til taken into the stomach of the mosquito. The possibility of 

 parthenogenesis will be referred to latir. In appearance they are 

 round or oval, and in this fever may be twice the size of the 

 red cell. As a rule a narrow margin of red cell is visible after Ro- 

 manowski stains, although the gamete may lie free in the plasma. 

 Unlike the schizonts, the gametes have the pigment uniformly dis- 

 tributed throughout the body and there is no indication of segmen- 

 tation. The young sporonts are distinguished from schizonts by the 

 absence of the vacuole, and, when a little older, by a larger amount 

 of hemozoin. 



Plasmodium malariae. The quartan parasite has a life cycle of 

 seventy -two hours, or twenty-four hours longer than the tertian, and 



"N 



FIG. 189. PLASMODIUM MALARIA. (Army FIG. 190. PLASMODIUM MALARLE. (Army 

 Med. School Collection, Washington, Med. School Collection, Washington, 



D. C.) D. C.) 



the paroxysms come on every third day, or, according to the Italian 

 method of reckoning time, on the fourth day. The young rings of the 

 plasmodium malarice are indistinguishable from young tertian rings, 

 but the diagnosis may be made on older forms. The bleaching, enlarge- 

 ment and stippling of the erythrocyte characteristic of tertian is never 

 found in quartan fever, the infected erythrocyte being almost normal 

 in appearance. The well-grown quartan parasite does not show 

 ameboic changes but assumes a. band form, more or less wide, stretch- 

 ing across the red cell from b( rder to border ; with increasing age the 



