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.
| Fig. 4.—PHASES OF CARYOTROPHA MESNILII, SIEDL. (PAR. POLYMNIA NEBULOSA). |
a, Young schizont in a cluster of spermatogonia; the host-cell (represented granulated) and two of its neighbours are greatly hypertrophied, with very large nuclei, and have fused into a single mass containing the parasite (represented clear, with a thick outline). The other spermatogonia are normal. b, Intracellular schizont divided up into schizontocytes (c), each schizontocyte giving rise to a cluster of merozoites arranged as a “corps en barillet”; spg, spermatogonia; h.c, host-cell; N, nucleus of host-cell or cells; n, nucleus of parasite; szc, schizontocyte; mz, merozoites; r.b, residual bodies of the schizontocytes. (From Minchin, after Siedlecki.)
Plate II.
| Fig. 5.—SCHIZOGONY OF ADELEA OVATA, A. SCHN. (PAR. LITHOBIUS FORFICATUS). |
a-c, ♀ generation; d-f, ♂ generation. a, Full-grown ♀ schizont (megaschizont), with a large nucleus (n) containing a conspicuous karyosome (ky). b, Commencement of schizogony; the nucleus has divided up to form a number of daughter-nuclei (d.n). The karyosome of stage a has broken up into a great number of daughter-karyosomes, each of which forms at first the centre of one of the star-shaped daughter-nuclei; but in a short time the daughter-karyosomes become inconspicuous. c, Completion of schizogony; the ♀ schizont has broken up into a number of megamerozoites (♀ mz) implanted on a small quantity of residual protoplasm (r.p.). Each ♀ merozoite has a chromatic nucleus (n) without a karyosome. d, Full-grown ♂ schizont (microschizont), with nucleus (n), karyosome (ky), and a number of characteristic pigment-granules (p.gr). e, Commencement of schizogony. The nucleus is dividing up into a number of daughter-nuclei (d.n), each with a conspicuous karyosome (ky). f, Completion of schizogony. The numerous micro-merozoites (♂ mz) have each a nucleus with a conspicuous karyosome (ky) at one pole, and the protoplasm contains pigment-granules (p.gr) near the nucleus, on the side farthest from the karyosome. (From Minchin, after Siedlecki.)
| Fig. 6.—ASSOCIATION AND CONJUGATION IN ADELEA OVATA. |
a, Young microgametocyte (♂ gamc.) attached to a megagametocyte (♀ gamc.). The nucleus of the microgametocyte gives rise to 4 daughter-nuclei (c) which become (d) 4 microgametes (♀ gam.). e, One of the microgametes penetrates the megagamete, which forms a fertilization-spindle composed of male and female chromatin (♂ and ♀ chr.). The other 3 microgametes and the residual protoplasm of the microgametocyte (r.p.) perish. The karyosome of the megagamete has disappeared, as such. f, Union of the chromatin of both elements, to produce the zygote-nucleus (n.zyg.). (From Minchin, after Siedlecki.)
| Fig. 7.—SPORES OF VARIOUS COCCIDIAN GENERA. |
a, Minchinia chitonis (E.R.L.), (par. (Chiton); b, Diaspora hydatidea, Léger (par. Polydesmus); c, Echinospora labbei, Léger (par. Lithobius mutabilis); d, Goussia motellae, Labbé; e, Diplospora (Hyaloklossia), lieberkuhni (Labbé), (par. Rana esculenta); f, Crystallospora crystalloides (Thél.), (par. Motella tricirrata). (From Minchin; b and c after Léger, the others after Labbé.)