244 Phillips on a Comparative Study of the 



He established the fact of such continuity, but at times the 

 connecting substance might be composed of cyanophycin 

 rather than protoplasm, as was the case with heterocysts, 

 where it formed a plug to close the pore. He considered 

 the connecting thread to be single and to pass through a 

 pore in the middle of the partition wall. In Oscillaria this 

 continuity assisted it to act as a unit in its movements. He 

 was unable to demonstrate a nucleus or chromatophore. By 

 means of micro-chemical methods hewas able to demonstrate 

 granules, partly imbedded in the protoplasm and partly 

 applied to the wall (the "schleimkugeln" of Schmitz) formed 

 of a gelatinous substance which, he believed, replaced starch 

 in these forms, and which he termed cyanophycin. These 

 granules were secreted by the transverse walls in dividing 

 cells and had the following properties ; the substance was 

 homogeneous, they became swollen and disappeared when 

 placed in sulphuric or hydrochloric acid, Millon's reagent 

 gave no color to them though they were turned slightly blue 

 by iodine (5) or chlor-zinc iodide. Isolated cells of Oscil- 

 laria viewed from the "end" showed that the granules were 

 arranged in a circle around the central opening through 

 which passed the connecting thread of protoplasm or cyano- 

 phycin. The cell wall and sheath were composed of a sub- 

 stance akin to cuticle. This sheath was very delicate in 

 Oscillaria. and was often overlooked. It became thick over 

 the rejuvenated ends of the filaments, forming thus a kind 

 of protective cap. In spore formation, cyanophycin in the 

 cell became the chief part of the spore and the cell seemed 

 to rejuvenate. An encysting wall was then formed around 

 the spore and the mother wall disintegrated. 



After investigating numerous forms of Tolypothrix, 

 Oscillaria, Nostoc, SpiruUna, etc., Zopf (95) concluded that 

 the filamentous forms were but one stage in the life-history 

 of the "Spaltalgen." By growing filamentous forms on 

 tiles imbedded in moist sand in such a way that very little 

 nourishment could be obtained by them, he was able to 



