204 Phillips on a Comparative Study of the 
acid, but digestion with trypsin in an alkaline fluid causes 
them to disappear. They are usually scattered throughout 
the peripheral protoplasm, or aggregated at times along the 
division walls of the cells. Especially do they take the latter 
position in Oscillaria. 
Vacuoles. 
Vacuoles have been described in this group by different 
authors. Hieronymus and Palla declared that they were 
normal structures, while Gomont and Zacharias claimed 
equally strongly that they did not occur in active cells. 
Zukal considered that they appeared upon degeneration of 
the cell. This is the case in all of the organisms examined 
by the writer. Vacuoles, as normal structures, do not 
appear in any of the Cyanophycee. ‘They can be made to 
appear by cultivating the organisms in darkness or in an 
unpropitious environment. When they appear as patho- 
logical conditions upon the breaking down of the cells, they 
have no tonoplast as described by De Vries (21B) and 
Went (83), but are merely globules of disintegrated cell 
substance enclosed in openings within the protoplasm. That 
they are formed by the disintegration of the protoplasm is 
plainly evidenced by the presence of oil and other similar 
products. The vacuoles described by some authors as 
occurring in the central body, sometimes even filling it com- 
pletely, are in reality the larger or smaller hollow chromatin 
vesicles as described above. 
Other Cell Constituents. 
The chemical composition of the various parts of the 
protoplast has been spoken of in the different sections treat- 
ing of the organs in detail. There are, however, some sub- 
stances in the cells of the Cyanophycez, the presence or 
absence of which have certain bearings upon the interpre- 
