222 



THE SPOROZOA 



already been noticed incidentally, but a few other points require 

 special mention in other forms. 



The schizogony is usually very similar in its characters to that 

 described above, and always lacks cyst-membranes of any kind, whether 

 round the schizont as a whole or in the form of spore-envelopes. The 



FIG. 55. 



Schizogony of Addea ovata, A. Schn. (par Lithobius forflcatus), after Siedlecki [55]. a-c, ? 

 generation ; d-f, <J generation, o, full-grown ? schizont (?>iacroscAt07iO, 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), each consisting of a number of 

 rods of chromatin arranged in a star-shaped manner in a clear space. 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, and seem to be absorbed, or to be got rid of in some way. 

 c, completion of schizogony ; the $ schizont has broken up into a number of nutcramerozoites 

 ( $ mz), implanted on a small quantity of residual protoplasm (r.p). Bach ? inerozoite has 

 a chromatic nucleus (n) without a karyosome. d, full-grown (J 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 

 micromerozoites ( <J 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 furthest 

 from the karyosome. 



term " Eimerian cyst," so frequently employed, is therefore a misnomer. 

 There is always a large amount of residuary protoplasm, and when the 

 formation of the merozoites is completed, they very frequently take on a 

 characteristic arrangement, like that of the divisions of an orange or the 

 staves of a barrel ; hence this stage is termed by French writers the 

 "corps en barillet" ; it is homologous with the "stade en rosace" of the 



