PLASMODHD^. 245 



the male crescent possessing a more delicate capsule than 

 the female crescent. Wenyon (1926) is not convinced that 

 any such capsule exists, and is of the opinion that the Hfe- 

 cycles of the three species of malarial parasites are so similar 

 in every respect that, even if a capsule did exist, it would 

 not justify generic distinction. In my opinion the life-cycle 

 is bound to be similar within the same family, and the difference 

 in form of the gametocyte is a sufficiently important feature 

 to serve as a basis for generic distinction. Stiles (1928) 

 has announced that the International Commission of Zoological 

 Nomenclature has placed both Laverania and Plasmodium 

 in the official list of generic names. 



History of the Discovery of Malarial Parasites and the part 

 played by the Mosquitoes. — It will not be out of place to 

 briefly review here the history of the discovery of malarial 

 parasites and of the part played by the mosquitoes in their 

 transmission. The study of the HiEMOSPOBiDiA (or Hsemo- 

 cytozoa or Hsematozoa as they were then generally called) 

 began with the discovery by Ray Lankester in 1871 ofDrepani- 

 dium ranarum in the blood of the frog. Human malarial 

 parasites are said to have been seen, but their significance was 

 not comprehended until Laveran pubHshed his investigations 

 (1880). Golgi (1885) demonstrated the relationship existing 

 between the life- cycle of the parasites within the human body 

 and the occurence of the febrile attack. In India Vandyke 

 Carter (1888), Evans (1888), Hehir (1893), Crombie (1894), and 

 Ronald Ross (1895) were the earliest to study the malarial 

 parasites in man. Ross (1895) observed the process of 

 " flagellation " of crescentic parasites in the stomach of 

 mosquitoes fed on the blood of a malarial patient. MacCullum 

 (1897) found that the " flagella " oi Hsemoproteus (Halteridium) 

 and of sestivo- autumnal parasites constitute the male element, 

 and serve to impregnate the " pigmented spheres " or female 

 element, and further observed in the former that the im- 

 pregnated spheres become converted into motile " vermicules." 

 Ross (1897), working at Secunderabad, fed mosquitoes upon 

 human blood containing " crescents." After examining 

 hundreds of mosquitoes fed on malarial blood, with negative 

 results, he obtained a few mosquitoes with spotted wings, 

 in which he discovered pecuHar pigmented cells lying within 

 the walls of their stomachs. The pigment was similar to that 

 within the malarial parasites in the blood upon which the 

 mosquitoes had been fed. Ross concluded that he had found 

 the mosquito which served as a host for the parasite. In 

 February 1898 he again referred to his experiments with 

 crescentic parasites and dapple- winged mosquitoes. After 

 this, working at Calcutta, Ross observed the development 

 of the malarial parasite of birds, Proteosoma, in a species of 



