PLASMODIUM FALCIPARUM 227 



blood. The parasite may be studied in fresh film preparations, 

 and by staining dried films by methylene blue and eosin, Romanow- 

 sky's, or Jenner's methods. They are much more frequent in the 

 pyrexiat period, and when quinine has not been given. 



The various plasmodia are transmitted to man invariably by the 

 anopheles mosquito, in the bodies of which they undergo a different 

 (sexual) existence. It has been positively demonstrated that the 

 various plasmodia undergo an alteration of generations and require 

 two different hosts for their development, i.e., mosquito, man. 



The asexual development, or schizogony, takes place in the blood 

 of man, the sporogony, or sexual development, in the body of the 

 anopheles mosquitoes, the bite of which sets up an infection in man, 

 since the sporozoites of the various plasmodia are developed in the 

 salivary glands of these mosquitoes. In the act of biting, the sporo- 

 zoites reach the erythrocytes where they become the intra-corpus- 

 cular hyaline bodies beginning again their asexual cycle of develop- 

 ment in the blood. 



That the mosquito is the intermediate host of the malarial para- 

 site and that the infection in man follows bites by infected mosqui- 

 toes has been abundantly proven. The mosquitoes that act in this 

 way are the various Anopheles; the Anopheles maculipennis being the 

 offender most frequently. The freshly formed schizonts in the 

 blood of an infected man are conveyed into the intestines of the 

 mosquito. Here sexual reproduction of the parasite begins. The 

 male elements, filamentous microgametcs, penetrate the female ele- 

 ments, macro gametes (spheres), and after a time become mobile fusi- 

 form bodies, ookinets. These bore into the intestinal walls of the 

 mosquito and there remain. After a time they are converted into 

 round bodies, or oocysts. The nucleus of the oocysts divides rapidly 

 and other daughter nuclei are formed, and new cells called sporo- 

 blasts. After about eight days these form the sporozoites. The 

 number of sporozoites in each oocyst varies from hundreds to many 

 thousands (often 10,000). These oocysts burst and the sporozoites 

 in the circulation find their way to the salivary glands of the mos- 



