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V 



346 THE PROTOZOA 



species from the propagative, spore-producing phase, and was given the 

 generic name Eimeria, with type E. falciformis of the mouse. When the true 

 connection between the two forms was discovered, Eimeria became a synonym 

 of Coccidium, or of whatever the generic name of the sporont might be (e.g., 

 Eimeria nepce, from Nepa cinerea, =Barr<ms8ia ornata). The nomenclature - 

 purists have, however, sought to abolish the generic name Coccidium, and to 

 replace it by Eimeria, on the ground of priority a procedure which, in my 

 opinion, is contrary to public policy, and should not be followed, anything in 

 the law of priority notwithstanding. 



4. The merozoites (agametes), the daughter-individuals produced 

 by schizogony, are set free from the remains of the host-cell (cyto- 

 cyst). Each merozoite is very similar to a sporozoite in form, 

 structure, and movements, differing only in minor points of detail ; 

 for instance, in C. schubergi the nucleus of the merozoite has a distinct 

 karyosome, wanting in that of the sporozoite. The merozoites 

 penetrate into epithelial cells, and become trophozoites which may 

 develop in one or the other, of two ways (1) into schizonts again, 

 repeating the schizogony already described ; (2) into sporonts 

 (gamonts), destined to produce gametes and resistant propagative 

 phases. 



5. The growth of the sporonts is slower than that of the schizonts, 

 and differs in the two sexes ; in the male sporont (Fig. 152, G (J) 

 the cytoplasm remains clear, free from enclosures, but in the female 

 (Fig. 152, G ? ) it becomes crowded with reserve nutriment, stored 

 up as a provision for the reproductive phases, in the form chiefly 

 of so-called " plastinoid spherules." 



In C. schubergi the female sporonts differ also from the spherical male form 

 in being bean-shaped, but this is a specific peculiarity. In some species the 

 female sporonts are very much larger than the male, as in Adelea ovata 

 (Fig. 154), Orcheobius herpobdellce, etc. In the last-named species, parasitic in 

 the testis of the leech Herpobdella atomaria, the trophozoites which become 

 schizonts are parasitic in the cytophores ; but the merozoites destined to become 

 sporonts are quite motionless, and lie free in the lymph, whence they are 

 taken up passively by the lymphocytes, often several by one such cell. In the 

 lymphocytes they associate in couples, a male and a female sporont together, 

 and the female sporonts grow into long, monocystid-like bodies (Kunze). 



6. When full-grown, the sporonts proceed to gamete-formation : 

 (a) In the male sporonts (Fig. 50, p 102 ; Fig. 152, H <$ , I (?) the 



nucleus gives off chromidia into the cytoplasm, and the chromidia 

 collect at the surface of the body ; the old nucleus, now much poorer 

 in chromatin, and with its karyosome still distinct, remains in the 

 centre of the body. The chromidia become condensed and con- 

 centrated into patches to form secondary nuclei, which finally take 

 shape as elongated compact bodies consisting of dense chromatin ; 

 each such nucleus, together with an almost imperceptible quantity 

 of cytoplasm, forms the body of a male gamete (microgamete), and is 

 set free, while the greater part of the body of the sporont, together 

 with its old nucleus, degenerates and dies off as residual protoplasm. 



