THE H^MOSPORIDIA 361 



the corpuscles. An effect commonly seen is the so-called " stippling " 

 (Tiipfelung) of the corpuscles, which exhibit a dotted appearance (Scjiuffner's 

 dots). 



I 

 The merozoites, when set free, penetrate into other corpuscles, 



and become in their turn trophozoites, which may either grow 

 into schizonts again and repeat the process of multiplication by 

 schizogony, or may grow into sporonts. As in Coccidia. a number 

 of generations of schizogony succeed each other before sporonts 

 are produced. At first the parasites are not sufficiently numerous 

 to be perceptible in the blood or to evoke febrile symptoms, and 

 during this, the so-called " incubation-period," schizogony alone 

 .occurs, in all probability ; but when the numbers of the parasite 

 are sufficient to affect the health of the host, the reaction of the 

 host against the parasite probably stimulates the production of 

 the propagative phases. The trophozoites which grow into sporonts 



FIG. 156 continued : 



disappears ; in 6 the parasite is full-grown and its nucleus is beginning to 

 divide. 7, 8, Progress of the nuclear divisions, complete in 8. 9, Division 

 of the body of the parasite to form the merozoites ; the blood-corpuscle 

 beginning to degenerate. 10, The parasite has divided up into sixteen mero- 

 zoites, leaving the pigment-grains in a small quantity of residual protoplasm ; 

 the corpuscle has completely disappeared and the merozoites are set free. 



VI., Vila., VII6., Formation of the gametocytes of pernicious malaria 

 (Plasmodium falciparum) ; the gametocytes arise from the intracorpuscular 

 parasites by a series of stages similar to those represented in II. V., but 

 without a vacuole in the body. In P. falciparum the ripe gametocytes have 

 the form of crescents, as shown, but in the tertian and quartan parasites the 

 gametocytes are simply rounded, as Villa, and VIII&. Vila., Male crescent 

 with larger nucleus and scattered pigment ; VII6., female crescent, with a 

 smaller nucleus and the pigment more concentrated round it. (N.B. Vila, 

 and VII6. are drawn on too small a scale ; the crescent should be as large 

 as XIII.) 



VIII. XIII., Stages of the sexual generation of the tertian parasite in 

 the stomach of the mosquito, after Schaudinn. a, Male forms; &, female 

 forms. (In pernicious malaria the crescents round themselves off, become 

 free from the corpuscle, and assume forms similar to VIII. a and &.) VIII., 

 Rounded - off parasites free from the corpuscle. IX., Gamete-forma- 

 tion ; in a the nucleus is divided into eight ; in 6 the nucleus has passed to 

 the surface of the body. X., Further stage ; in a the body of the gametocyte 

 is throwing off the long slender microgametes, one of which is represented 

 free ; in 6 the nucleus is dividing to throw off a reduction-nucleus. XI., 

 Process of syngamy ; a male gamete is seen penetrating the body of a female 

 gamete. XII., Zygote shortly after fertilization ; the body is growing out 

 and becoming vermiform, with the synkaryon at the hinder end ; male and 

 female chromatin still distinct ; near the zygote is seen a clump of degenerating 

 microgametes. XIII., Motile ookinete formed from the zygote ; the syn- 

 karyon, with male and female chromatin still distinct, is seen near the middle 

 of the body ; the pigment- grains are at the hinder end of the body, whence 

 they are soon rejected. 



XIV. XVIII., Sporogony: diagrammatic. The ookinete (XIII.) pene- 

 trates the stomach-wall and becomes encysted (XIV.) ; its nuclei multiply 

 (XV.), and it forms a number of sporo blasts so called (XVI.) ; in each sporo- 

 blast the nucleus divides to form a great number of small nuclei, which grow 

 out in tongue-like processes from the surface to form the sporozoites (XVII.) ; 

 the ripe cyst contains great numbers of sporozoites with a certain amount of 

 residual protoplasm ; the sporozoites when set free (XIX.) pass into the 

 salivary glands, and thence through the proboscis into the blood of the 

 vertebrate again. 



