NUCLEI AND KINETIC ELEMENTS 



119 



presumably cliAides to form the daughter plates as shown in 

 Schaudinn's well-known figure, or to division figures like that of 

 Cen tropyx is a culea ta . 



Another widely distributed type of division figure is derived from 

 vesicular nuclei in which the chromatin is not contained in one or 

 more endosomes but is distributed peripherall\' about the nucleus 

 where it usually forms a distinct chromatin reticulum. Such nuclei 

 usually contain an endosome which may be the most conspicuous 

 structure of the nucleus. In Amoeba crystaUigera the peripheral 

 chromatin appears to be passively divided without any appreciable 

 change in its make-up. In Amoeba tespertilio the peripheral chro- 



FiG. 62. — Nuclear divi.sion in Collodictyuni triciliatum. (After Belar.) 



matin is similarly divided and distributed but the endosome appar- 

 ently contains some chromatin in addition for a complete division 

 figure is formed from its substances, chromatin-like granules forming 

 a nuclear plate (Fig. 39, p. 82). In other cases, as for example 

 Endamoeba intestinalis and E. cobayce, the peripheral chromatin is 

 broken up into chromomeres, which collect in the center of a 

 spindle from the linin of the nucleus and with centrioles at the poles 

 (Fig. 26, p. 63). 



In still another general type, derived also from vesicular nuclei, 

 the chromatin in the form of chromomeres is suspended in a loose 

 reticuhun. In Opalina they appear to be aggregated in a few larger 

 granules, which flivide where they happen to be without further 



