4 Myxophyceae 



of the cell, and its external form is largely determined by the shape of the 

 cell ; as for instance, in the numerous forms with disc-shaped cells where 

 it is much compressed. The evidence brought forward concerning the 

 precise nature of the central body is very conflicting, but most of the recent 

 investigators agree that it differs considerably in its structural details from 

 the nucleus of higher plants. The various authors come mostly within three 

 categories : those who state that the central body is not a nucleus ; those 



Fig. 3. Filamentous forms of Blue-green Algfe with conspicuous sheaths. A, Schizothri.c 

 Miilleri Nag. ; D, S. lardacea (Ces.) Gom. ; C, Dasygloea amorplm Berk. All x 460. 



who regard the central body as a definite nucleus, comparable with that 

 in higher types of cells ; and those who hold the view that it is a nuclear 

 structure of a somewhat primitive type. 



I. Borzi ('86) failed to demonstrate the presence of a nucleus, and both Stockrnayer 

 ('94) and Zukal ('92) have declared that the central body has no relation to the nuclei 

 of higher plants. Marx ('92), whose work was largely micro-chemical, concluded that it 

 was not possible to demonstrate the existence of a nucleus. Zacharias ('90 '92) found 

 that the central body differed in all respects from a true nucleus, and that there was no 



