Cytology and Movements of the Cyanophycece. 243 



A criticism on the work of both Schmitz and Wille is 

 that they used only one stain, hsematoxyhn, and in part of 

 his experiments, Schmitz used only fresh material. The 

 use of fresh, unchanged material is of course preferable if 

 supported by other observations, but confirmatory tests are 

 quite essential. Observational results without such safe- 

 guards are never conclusive though Wille's descriptions 

 seem very accurate. His conclusions would have carried 

 much greater weight if he had left figures illustrative of 



what he saw. 



Tangl (78) was unable to find a nucleus, but this was 

 probably due to poor methods. He described an Oscillarian 

 organism, Plaxonema oscillaris, which had a rod-shaped 

 chromatophore. However, as Molisch (.SS) showed phy- 

 cocyanin to be a crystalline substance, Gomont (32) con- 

 sidered this chromatophore to be merely a crystallization of 

 that pigment. Tangl described zoogloese which appeared 

 on culturing Plaxonema as follows : "The filaments first lose 

 their power of motion, coming to a standstill after the fol- 

 lowing changes, which are of two kinds (a) the filaments 

 either separate into single cells, or (&) in certain places there 

 arise small zoogloese which enclose a changing number of 

 shorter or longer parts of filaments. . . . The plasma of 

 the filaments assumes a finely granular appearance, the glit- 

 tering granules on the partition walls alone remaining of the 

 earlier contained bodies, the chromatophore becomes loos- 

 ened and withdraws from the walls." From this descrip- 

 tion it seems hardly probable that the organisms were in a 

 good state of preservation, and his conclusions for that 

 reason scarcely bear upon the morphology of the Cyano- 



phycese. 



Borzi (6) worked on Nostoc, Anahaena, Oscillaria, Sper- 

 mosira, Cylindrospermum and Sphaerozyga, and endeav- 

 ored to determine intercellular protoplasmic continuity pri- 

 marily, but his conclusions in other lines are as interesting, 

 or more so, than in the line that he started to investigate. 



