” 
266 A. B. MACALLUM. 
in the central body. These are the ‘‘cyanophycin” granules 
of Palla and such as Biitschli found in Oscillariz to be un- 
affected by hematoxylin but markedly stained by eosin. They 
may give a reaction for iron, but not always one of the same 
intensity, for in Oscillariz it was very slight, and in one pre- 
paration of Microcoleus terrestris none was obtained, 
while in preparations from the same specimen of fresh material 
made a few days later than the other, the reaction was quite 
distinct. In two preparations of Scytonema sp. the granules 
gave no reaction, aresult which I attribute to a deterioration 
of the solution of the sulphide reagent then used. In Cylin- 
drospermum majus these granules give an intense reaction 
for iron (fig. 8). Theiron is not less firmly combined in the 
substance of these granules than it is in the chromatin, for 
in the last mentioned species the glycerine and sulphide mix- 
ture brought out its complete reaction only after an applica- 
tion of ten days or more. Within twenty-four hours after the 
addition of the mixture, they gave, in all the species in which 
they were iron-holding, a slight greenish reaction. I have 
not succeeded in demonstrating the presence of iron in them 
after the use of sulphuric acid alcohol, and the explanation 
for this is that the latter reagent liberates, but at the same 
time wholly extracts the iron in these granules, the substance 
of which, unlike chromatin, is incapable of retaining it. 
8. Beyond the fact that the “ cyanophycin” granules may 
contain iron, there is nothing to show a relationship, chemical 
or physiological, between them and the vesicles. From their 
situation the “cyanophycin” granules would, as Palla sug- 
gested, appear to be the assimilation product of the activity of 
the chromatophore, while the chromatin vesicles and granules 
might be regarded as due to processes of elaboration on the part 
of the central body. In Cylindrospermum majus, which 
grows on soft mud, the former are usually extremely abundant, 
but in twenty-four hours after placing the thallus in water, the 
granules diminish very much in number, and on the third day 
they may be wholly absent in very many of the filaments. 
Central vesicles, on the other hand, are in this form extremely 
