DEVELOPMENT OF THE MALARIAL PARASITES OF MAN 



I6 3 



fertilized females elongate very soon and are called ookinetes or 



"vermicides" (figs. 80, 17; 82). They penetrate the walls of the 



stomach, pierce the epithelium (fig. 80, 18, ig), and remain lying 



between it and the superficial stratum 



(tunica elastico - muscularis). Then they 



become rounded and gradually develop 



into cysts which grow larger and are 



finally visible to the naked eye, being 



called oocysts (figs. 80, 20-24 ; 83). Their 



size at the beginning is about 5 //,, the 



maximum that they attain is 60 //,, only 



exceptionally are they larger. 



The sporulation (figs. 80, 21 25; 84), 

 which now follows, begins with repeated FIG. 83. Section of the 



multiple fission of the nucleus. Long stomach of an Anopheles with 



P cysts (oocysts) of the malignant 

 before the definitive number of nuclei, tertian parasite. (After Grassi). 



which varies with the individual, is attained 



the protoplasm, according to Grassi, begins to segment around the 

 individual large nuclei but without separating completely into cell 

 areas. According to Schaudinn, 

 however, there is a condensation 

 of the outstanding protoplasmic 

 strands. It is certain that the num- 

 ber of nuclei increases with simul- 

 taneous decrease in size. They 

 soon appear on the surface of the 

 strands or sporoblasts, surround 

 themselves with some cytoplasm 

 and then elongate (fig. 84). In 

 this manner the sporozoites are 

 formed and break away from the 

 unused remains of the cytoplas- 

 mic strands of the sporoblasts 

 (fig. 80, 26). The number of the 

 sporozoites in an oocyst varies from 



Several hundreds to ten thousand. FIG. 84. Four different sporulation stages 



of malarial parasites from Anopheles maculi- 



The sporulation is influenced in its pennis, much magnified. a e, of the 

 duration by the external temperature malignant tertian parasite ; a, four to four 

 ir * T o u N T ^u i- an " a na -lf days after sucking ; I and c, five 



(Grassi, Jansc., Schoo). In the tertian to six days J ter sucking . ^ of the tertian 



parasite it takes place quickest at a parasite, eight days after sucking. (After 



temperature of 25 to 30 C. and takes Grassi.) 



eight to nine days. A temperature a 



few degrees lower has a retarding effect (eighteen to nineteen days at 18 to 20 C). 



A still lower one has a restraining or even destructive effect. Temperatures over 



35 C. also exercise a harmful effect. The malignant tertian parasite seems to need 



a somewhat higher temperature and the quartan parasite a lower one. 



