284 Phillips on a Comparative Study of the 



ments. Butschli found that when the Cyanophyceae were 

 digested in artificial gastric juice the central body floated 

 free in the otherwise empty cell and showed a Brownian 

 motion. The central body of the resting Cyanophycean cell is 

 therefore usually composed of larger or smaller hollow vesi- 

 cles of chromatin, as claimed byLauterborn (47) for Diatoms. 

 These vesicles are imbedded in a finely granular ground 

 substance, which sends radiating lines toward the periphery, 

 piercing the chromatophore. If a cell wall be ruptured and 

 the cell contents pressed out, these hollow chromatin vesicles 

 may be seen lying isolated within the protoplasm (Fig. 24). 

 In cross sections the vesicles are shown to be quite numer- 

 ous (Fig. 31) and of a small size in the naturally grown 

 plant, but in material, grown in the full culture solution they 

 are relatively large and few in number (Fig. 30). Radi- 

 ating from the central body are seen fine granular kino- 

 plasm-like processes of the ground substance, which pierce 

 the chromatophore and pass out to the cell wall where 

 they form the central portion of protoplasmic ciliary-like 

 growths, about one-half to one micron in length on the 

 sides of the organism. In Oscillaria there may be as many 

 as four such processes shown in optical section on one side 

 of the cell, while on the other side only one or two may 

 be seen. In Cylindrospermum these ciliary processes are 

 more numerous and regularly distributed. 



The central body has no membrane surrounding it. In 

 this it is different from the nucleus of higher plants. Hier- 

 onymus has suggested that this condition be termed an 

 "open nucleus." Palla, Strasburger and Fischer described 

 a delicate membrane surrounding the central body, but in 

 this investigation, nothing of the kind has been found. The 

 opinions of various investigators of the Cyanophyceae do 

 not agree as to the nuclear nature of the central body. 

 Zukal did not consider it to be a nucleus, but attributed 

 that function to the cyanophycin granules, while he re- 

 garded the central body as the cytoplasm. Hieronymus 



