264 Phillips on a Comparative Study of the 



resembling one in the Cyanophyceas. Division was direct, 

 the central body first showing the effects of the process. 

 When a large spherule of chromatin-like substance was 

 present, it might pass into one daughter cell or it might be 

 mechanically divided between the two daughter cells. It 

 seems that some, at least, of Macallum's conclusions are 

 scarcely warranted by his experiments. He found that there 

 was a chromatin-like substance present, still he denied the 

 presence of an}'thing resembling a nucleus. Were we to 

 take the predominance of authority to determine a definition 

 of nucleus, we must let nuclein or nucleus stand as fairly 

 synonymous with chromatin. Where one is found, the 

 other is indicated, at least indirectly. Macallum's error, like 

 that of many others, seems to be in the mistaken idea that 

 a nucleus must be a definitely bounded body. 



Strasburger (76) claimed that there were special cells, 

 no longer capable of division, in which several nuclei had 

 been formed by fragmentation. The cell nucleus was sur- 

 rounded by a colored peripheral layer or chromatophore 

 in which cyanophycin grains were found. The function of 

 these grains was unknown. Mucous globules were also dis- 

 posed in the vicinity of the nucleus, and vacuoles were occa- 

 sionally present. The cell wall was composed of cellulose, 

 often distinctly stratified, and its outer layer might undergo 

 mucilaginization. Multiplication was effected in a vege- 

 tative manner, e. g., in the Oscillariaceje, by the rounding 

 off of two adjacent cells to form a germinal segment. The 

 whole filament might break up into short hormogonia, each 

 of which then grew out into a long filament. He accepted 

 Hegler's conclusions of a mitotically dividing nucleus. 



Bornet and Flahault (4) considered that the sheath of the 

 Cyanophyceae received the color which it often possessed 

 through the action of light and air. Working upon Tolypo- 

 thrix lanata, they were unable to discover anjlhing akin 

 to a nucleus. Bornet (3) investigated also the structure 

 of the cells of Nostoc in lichens, and noted that their con- 



