118 



BIOLOGY OF THE PROTOZOA 



In another group of types the chromatin of the resting vesicular 

 nucleus is contained also in a definite endosome, but, in preparation 

 for division, the endosome fragments into minute chromomeres, 

 which may be strung out in lines through the nucleus, these strings 

 being di\'idefl transversely at division. Or the chromomeres may 

 be aggregated in a fairly homogeneous transverse plate in the 

 center of the dividing nucleus. The former condition is illustrated 



7/ V^ 



a"*/. 









B 



I J 



'' km '^l 



^-^^ iiii '>'•■' 



-S % 



G 



E ^^ 



K| i '' 



i'v-.r « 









■E jfa %i 



'-»v , ;■»: 



^ 



Fig. 61. ^Successive stages in the nuclear division of a simple Aniaba. (After 

 Wasielewsky and Kiihn.) 



by the nucleus during vegetative division of Aciinosphoerium eich- 

 hornii according to Hertwig, the latter condition by AcantJiocystis 

 acidcata (Fig. 60), Paramoeha chceiognathi, or the m^xomycete 

 Co77iatricJia ohtiisdia according to Lister. 



A slight modification of this type is shown by nuclei containing 

 multiple endosomes as in Pelomyxa bimwleafa which fragment at 

 periods of division, giving rise to a granular nuclear plate (?) which 



