204 



CYTOLOGY 



CHAP. 



two different phases of the Ufe cycle of Coccidium schubergi (Schaudinn, 

 1900). In the schizont (the asexual cycle), before nuclear division the 

 chromatin granules become massed together in little clumps and 

 irregular threads, in which, however, no definite longitudinal splitting 

 can be made out, and they do not get collected into an equatorial plate. 

 They sort themselves out in some way or other into two groups which 

 appear to be pushed apart by the elongation of the karyosome, which 

 contains, or takes the place of, the centrosome and achromatic figure. 

 The nuclear divisions in the oocyst of the same species, which cover 



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Fig. 84. 



Nuclear division in the asexual cycle of Coccidtum schubergi. (After Schaudinn, Z.J. A., 1900.) 



A-E, the schizont ; F-L, the oocyst. 



the first few divisions of the zygote nucleus after syngamy, are instructive 

 as showing how nuclei which appear to divide in the most purely amitotic 

 fashion may have undergone a previous reorganization which is presum-* 

 ably connected with the accurate partition of differentiated chromatin 

 elements between the daughter nuclei (Fig. 84, F-L). 



There is a prophase closely resembling that of a Metazoan mitosis 

 resulting finally in the formation of a relatively very thick and short 

 spireme. This, however, breaks up into irregular fragments which become 

 united to form a reticular nucleus again, and in this condition the nucleus 

 divides. Although, therefore, the actual division appears to be amitotic 

 it is difficult to avoid the conclusion that the previous arrangement of 



