i6 



ZOOLOGY 



SECT. 



n certain birds it has been fonnd that their presence is the cause of various 

 everish affections. The various forms of malaria in man have been proved to 

 )e due to the presence in the blood-corpuscles of the patient of parasites 

 lelonging to this order. The malaria-parasites, the history of which has been 

 arefuUy worked out, pass through a life-cycle comparable to that of Coccidium 

 [escribed above. In the trophozoite stage (Fig. 66, A — (?) they live as amoeboid 



\lfiJe]miliWe]»m\'L 



Fio. 60. — Life-History of Malaria Parasites. A-G, parasite of quartan fever, showing 

 development of trophozoite in a blood-corpuscle and the formation of merozoites ; 7/, 

 gametocyte of the same ; l-M, parasite of tertian fever to the formation of the merozoites ; 

 N, gametocyte ; 0-T, creacentic gametocytes of Laverania ; PS, formation of niiero- 

 garaetes or sperms ; I7~Wf maturation of mogag.imete or ovum ; X, fertilisation ; Y, zygote. 

 a, zygote enlarging in stomach of mosquito ; b-e, passing into the body-cavity ; /, g, develop- 

 ment of the contents into a mass of sporozoites ; h, sporozoites passing into the salivary 

 glands. (From Calkin's Protozoa, after Ross and Fielding Ould.) 



intracellular parasites in the interior of the coloured corpuscles of their host. 

 Here they multiply by schizogony — the products (merozoites) entering other 

 corpuscles. Some of the merozoites when they become established in the interior 

 of the corpuscles develop into rounded or crescentic bodies which become the 

 gametocytes (H, jV, 0, T). In order that the life-cycle may be completed, it is 

 necessary that the parasite at this stage should be taken into the interior of a 



