228 



THE SPOROZOA 



In Benedenia eberthi from Sepia, the sporozoites give rise to 

 indifferent trophozoites, which, however, when full-grown, become 

 gametocytes, which give rise at once to gametes, so that in this form 

 t/ie schizogonous cycle does not exist. 



The life-cycle of Benedenia is therefore of a simple type, and 



Fio. 58. 



Formation of gametes and conjugation, in Benedenia eberthi, Labbe (par. Sepia), xGOO, after 

 Siedlecki [52]. a, adult uuditferentiated trophozoite, capable of giving rise to microgametes, or 

 of becoming a macrogamete. n, nucleus; ky, .karyosome. b and c, formation of microgametes. 

 6, the nucleus of the gametocyte has divided into numerous daughter nuclei (d.n), which travel 

 to the periphery and project from the protoplasmic body, c, each daughter nucleus becomes an 

 elongated vermiform microgamete (<J gum), composed principally of chromatin, with a small 

 quantity of protoplasm, d, e, f, conjugation, d, in the macrogamete the nucleus places itself 

 in contact with the surface of the body, and by condensation of the chromatic network a mass 

 of chromatin ( ? chr) is formed at the pole of the nucleus furthest from the surface of the body. 

 ky, karyosome ; tj gam, microgametes swarming round the macrogamete in the vicinity of 

 the nucleus, e, a microgamete has penetrated the macrogamete, and is broken up to form a 

 mass of chroniatin-granules (f chr). A membrane, the oocyst (ode), is now formed round the 

 zygote, excluding the other microgametes. /, a fertilisation-spindle is formed, in which the 

 chroniatin-granules derived from the two gametes (& and 9 chr) is commingled. 



only differs from that commonly seen in Gregarines in certain 

 details of the conjugation. Its entire history may be expressed as 

 follows : 



Sporozoite-^- r? Gametocyte xnf Gametes 

 8 P orozoite^9Gametocyte->?Gam e te 



(Oocyst)xm 



The life-cycle of Adelea ovafa is similar, but the complication of 

 schizogony is introduced : 



Sporozoite-^- (J Gametocyte (Microschizont) x cJMerozoites (Micromerozoites)-^- . . . 

 Sporozoite-^- 9 Gametocyte (Macroschizont)x 9 Merozoites (Macromerozoites)-^- . . . 



8yrt)x 



Sporozoites. 



Finally, in Coccidium schubergi and other forms the fullest com- 

 plication is developed : 



Sporozoite-^-Schizontx Merozoites-^- . 

 Sporozoite-^-Schizontx Merozoites-^- . 



. SchizontsxMerozoites > 

 . Schizonts x Merozoites->- 



