420 MANUAL OF BACTERIOLOGY. 



each starting from the extracellular mature forms of the organism found in the 

 blood of the human host.* , j , 



Quartan Parasi'.e.— This resembles quite closely the ter- 

 tian parasite, but differs from it in certain respects. The 

 young, hyaline, intracorpuscular parasite is more highly 

 refractive, its ameboid motion is less marked and more slug- 

 gish, and the pigment granules are darker, much coarser, 

 and have very slight motility. The infected red corpuscles 

 are usually somewhat contracted instead of swollen, and their 

 color is apt to be darker, assuming a bronzed hue. The 

 full-grown parasite is much smaller than the corresponding 

 form of the tertian, approximating the size of a normal red 

 corpuscle. As segmentation begins, a characteristic appear- 

 ance develops which distinguishes the quartan organism, 

 namely, the coarse pigment granules are drawn toward the 

 center of the parasite in certain converging straight paths, 

 giving a stellate arrangement to the pigment, until finally it 

 becomes clumped entirely at the center in a solid mass. The 

 segmenting forms of the quartan parasite thus present a more 

 symmetrical arrangement of the spores, which often resemble 

 the petals of a " marguerite." These spores are oval and num- 

 ber only from six to twelve, being fewer than those of the ter- 

 tian segmenting parasite. The quartan extracellular forms 

 are smaller than those of the tertian, being about the size of a 

 red corpuscle, and contain coarse pigment granules in active 

 motility until degeneration occurs. Flagella may develop from 

 certain extracellular forms. The entire development of the 

 quartan parasite occupies about seventy-two hours. 



Estivo-autumnal Parasite. — This parasite develops to ma- 

 turity in from twenty-four to forty-eight hours, and is usually 

 regarded as representing a single species, though certain 

 observers claim to distinguish two distinct varieties. The usual 

 description of a single variety is here adopted. The youngest 



*Lyon. The Inoculation of Malaria by the Mosquito. A Review of the 

 Literature. Medical Record. February 17, igoo. 



