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 he was 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, Spirulina, 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 
