THE MALARIA-GERM, 



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site, in the blood cells of the human host, was correctly made out in 

 1888 by two Italian naturalists, Marchiafava and Celli, who showed 

 that the yoimg parasite, in a red blood corpuscle, is a minute granule 

 in which no structure could be made out. The granule grows, how- 

 ever, at the expense of the hsemaglobin of the corpuscle, and ultimately 

 forms spores (Fig. 3, a — /). During the life of the parent organism, the 

 products of growth are stored up in the parasite in the form of fine gran- 



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Fig. 1. Life Cycle of a Gregarine. [Mainly After Siedlecki.] 



Minute germs, sporozoites (A), enter epithelial cells lining the digestive tract 

 of a tunicate. Here they grow to a large size (B, C), ultimately breaking 

 through a cell-membrane and falling into the lumen of the digestive tract (D). 

 After some time in this adult condition, two individuals come together (E). 

 The nuclei divide repeatedly (F, G), and minute gametes are ultimately formed 

 (H, I). The gametes then fuse, two by two (I, J), forming the spores. The 

 two nuclei also fuse (K), and the joint nucleus then divides three times in 

 succession (L, M, N), forming right daughter-nuclei, which become the nuclei 

 of eight germs or sporozoites (0). The sporozoites are inclosed in small cal- 

 careous capsules which, in a new host, are dissolved by the acids of the digestive 

 fluids, thus setting free the sporozoites (A). 



ules. These, known as melanin granules, are left in the center of the par- 

 ent organism when the spores are formed, but at this period the blood 

 corpuscle, in which the sporulation occurs, disintegrates, and so liber- 

 ates the spores and the melanin in the blood plasm. Like the merozoites 

 of Coccidia, these spores make their way to new corpuscles, which they 

 VOL. Lix.— i:;; 



