THE SPOROGONY OF THE MALARIAL PLASMODIA 99 



separation of the sporoblasts is never complete, and thus it may. 

 happen that the residual bodies remain more or less connected 

 together for a long time. It is only when the sporozoites are 

 quite mature that a separation takes place ; then the sporozoites, 

 which are about 0*014 mm. in length and are provided with an 

 elongated nucleus, become detached from the residual body (fig. 43, d). 

 The size attained by the mature oocysts fluctuates between 

 0*03 0*09 mm. ; on an average, however, they seldom exceed 

 0*06 mm. The number of sporozoites in each oocyst varies to a 

 much greater extent (between a few hundreds and over 10,000). 



FIG. 43. Four different stages of sporulation of malaria parasites from Anopheles 

 maculipennis, strongly magnified, (a c) The pernicious parasite ; (a) four to four and 

 a half days after ingestion ; (b and c) five to six days after ingestion ; (d) tertian para- 

 sites, eight days after ingestion. (After Grassi.) 



According to all appearances the mature oocysts burst spon- 

 taneously and discharge their sporozoites into the body cavity of 

 the host. Here they are distributed by the circulation of the blood, 

 and after a few hours they already accumulate within tie salivary 

 glands. It has not been ascertained whether they penetrate actively 

 or are drawn in by chemical action. In any case, according to 

 Grassi and Ruge (10) they possess specific movements which hardly 

 differ from those of the sporozoites of coccidia, but are only observable 

 when the atmospheric temperature is rather high. 



During the process of puncture by the mosquitoes the sporo- 

 zoites are introduced into the wound with the saliva, and by 

 this means man becomes infected, as has been proved by experi- 



