PROTEOSOMA. 255 



the average number of merozoites formed being 15 ; in such 

 cases the infected corpuscles are altered in shape, pale in 

 colour, and have the nucleus displaced to one side of the 

 corpuscle. Sometimes two or more schizonts occur in a single 

 cell, and a crop of as many as 36 merozoites may result. 

 In the fully developed schizont the pigment is seen as a single 

 dark mass. Gametocytes are sHghtly elongate ovoid bodies 

 about the size of the largest schizonts, and closely resemble 

 those of Laverania. The female gametocyte stains more 

 deeply and has a more compact nucleus than the male. 

 Infection is transmitted from bird to bird by Cidex mosquitoes. 

 Sporogony is similar to that of the human malarial parasites 

 in Anopheles, the time occupied by the cycle varying with 

 temperature. Number of oocj^sts varies with the number of 

 gametocytes in the blood, in some cases the whole wall of the 

 stomach of the mosquito being studded with the oocysts. 



The parasite usually occurs in the blood of small birds like 

 the sparrow and lark, but can also be found in the blood of 

 larger birds such as the crow, owl, pigeon, partridge, duck, fowl, 

 etc. 



Remarks. — ^The species is of special interest, as it was while 

 investigating it that Ross (May, 1898) first discovered the 

 stages of fertihzation and oocyst formation in the stomach 

 of Culex sp. (probably C. fatigans Wied.). In June and July 

 of the same year Ross discovered the liberation of sporo- 

 zoites into the coelomic cavity of the mosquito and the invasion 

 of the salivary glands, and succeeded in infecting healthy 

 birds from infected Culex mosquitoes. He thus discovered the 

 whole of the transmission cycle in P. prsecox. He had previously 

 (1897) discovered oocysts of human malarial parasites in 

 Anopheles mosquitoes, and predicted that the transmission 

 cycle of human malarial parasites would be found to occur in 

 Anopheles mosquitoes, and that it would be identical with that 

 of P. precox in Culex, thus paving the way for the discovery 

 of the complete hfe- cycle of the human malarial parasites 

 by the Italian workers. 



Daniels (1899), Avorking at Calcutta, confirmed Ross's 

 observations. Koch, working in Italy (1899 a), studied the 

 development in Culex nemorosus {=Aedes nemorosus), and 

 Grassi (1899) in C. pipiens. Liihe (1900) clearly brought out 

 the relation of the hfe- cycle of malarial parasites to that of 

 CocciDiA, and introduced a terminology for various stages 

 that is in vogue till to-day. Ed. and Et. Sergent (1907) and 

 Neumann (1908) demonstrated that the complete cycle 

 could take place in a small proportion of Aedes segypti (Linn.) 

 {=^Stegomyia fasciata) that were fed on infected blood. Ed. 

 and Et. Sergent showed later (1918) that the development 

 could take place in certain other species of Aedes and Culex 



