I.-IV represents the schizogony, commencing with infection of an epithelial cell by a sporozoite or merozoite. After stage IV the development may start again at stage I, as indicated by the arrows; or it may go on to the formation of gametocytes (V). V-VIII represents the sexual generation. The line of development, hitherto single (I-IV) becomes split into two lines—male (VI ♂, VII ♂, VIII ♂), and female (VI ♀, VII ♀, VIII ♀), culminating in the highly differentiated micro- and mega-gametes. By conjugation these two lines are again united. IX, X, show the formation of the zygote by fusion of the nuclei of the gametes. XI-XV, sporogony. H.C', host-cell; N, its nucleus; mz, merozoite; szt, schizont; ky, karyosome (or fragments of same); n.n, daughter-nuclei of schizont; pl.gr, plastinoid grains; ooc, oocyst; n.zyg, zygote-nucleus (segmentation-nucleus); sp.m, spore-membrane (sporocyst); rp, residual protoplasm of oocyst (“reliquat kystal”); rp.sp, residual protoplasm of spore (“reliquat sporal”); sp.z, sporozoite. |