THE REPRODUCTION OF THE PROTOZOA 



111 



figure may be produced, as in Euglypha (Figs. 59, 60), only differing 

 from that of Metazoa in that the whole mitosis takes place within 

 the nuclear membrane, and consequently without any co-operation 

 of cytoplasmic elements. Chatton proposes for a mitosis of this 

 type- the term " mesomitosis," as distinguished from the more ad- 

 vanced type, or " metamitosis," in which a collaboration of cyto- 

 plasmic and nuclear elements is effected, and the entire karyokinetic 



FIG. 58. Division of Hcematococcus fluvialis. A, Resting 

 condition, the nucleus with a conspicuous karyosome 

 and fine grains of chromatin in an achromatize reti- 

 culum ; B, C, preparations for nuclear division, the 

 chromatin passing from the karyosome into the 

 nuclear reticulum ; D, further stage, the karyosome 

 in disruption and chromosomes beginning to bo 

 formed ; E, nuclear spindle ; F, division of the 

 nucleus complete, the karyosomes reconstituted in 

 the daughter-nuclei, the cell-body beginning to 

 divide ; G, division of the cell, the daughter-nuclei 

 of the normal resting type. After Reichenow 

 (97-5). 



figure lies free in the cytoplasm after disappearance of the nuclear 

 membrane. Before passing, on, however, to this more advanced 

 type, account must be taken of the more simple types of mitosis 

 seen in granular nuclei. 



Instructive examples of the division of nuclei, in which the 

 chromatin is not concentrated into a karyosome, but distributed 

 evenly throughout the achromatinic framework, are seen in the nuclei 



