MALARIAL FEVERS 243 



these crescents rapidly underwent changes resulting 

 in the formation of motile filaments, which become 

 detached from the parent body and continue to ex- 

 hibit active movements. In 1897 Ross ascertained 

 further that when blood containing crescents was 

 fed to a particular species of mosquito, living pig- 

 mented parasites could be found in the stomach 

 walls of the insect. Continuing his researches with 

 a parasite of the same class which is found in birds, 

 and in which the mosquito also serves as an inter- 

 mediate host, Ross found that this parasite enters 

 the stomach wall of the insect, and, as a result of its 

 development in that locality, forms reproductive 

 bodies (sporozoites), which subsequently find their 

 way to the veneno-salivary glands of the insect, which 

 is now capable of infecting other birds of the same 

 species as that from which the blood was obtained 

 in the first instance. Ross further showed that the 

 mosquito which served as an intermediate host for 

 this parasite could not transmit the malarial parasite 

 of man or another similar parasite of birds (Jialteri- 

 diuni). These discoveries of Ross have been con- 

 firmed by Grassi, Koch, and others, and it has been 

 shown that the mosquitoes which serve as inter- 

 mediate hosts for the malarial parasites of man be- 

 long to the genus Anopheles, and especially to the 

 species known as Anopheles claviger. 



