Cytology and Movements of the Cyanophycee. 283 
of hollow chromatin vesicles. The fact that these vesicles 
are often quite large, especially in plants that have been 
cultivated in solutions which feed the chromatin, had led 
some observers to consider that they were vacuolated. But 
their behavior during division excludes the possibility of 
such an assumption. The central body is of no definite 
form, its outline being determined by the number of balls 
within it. In Oscillaria the central body fills up a large por- 
tion of the width of the cell and in some forms quite as 
much of the length. In Cylindrospermum the central body 
is more elongated in the longitudinal axis of the trichome, 
often reaching from end wall to end wall. By cultivating 
the organism in a full culture solution for several days, or 
in a solution strong in soluble phosphates and iron which 
feed the chromatin, the outer stainable walls of the ““chroma- 
tin vesicles” become much more pronounced, while if cul- 
tivated in fluids which are poor in these substances and 
which would thus starve the chromatin they become degen- 
erated, losing their power to take up chromatin stains. This 
is quite in accord with the work of Brass (6A) who was 
able in this way to so starve the chromatin of the nuclei of 
Amoeba and Gregarinida as to make them quite poor in this 
element. Digestion of these organisms in artificial gastric 
juice made the central body much more evident, though it 
dissolved away the surrounding protoplasm and caused the 
chromatin vesicles to take a characteristic yellow luster. 
Experiments upon Spirogyra, carried on in the same culture 
dishes with the above, gave identically the same results as 
regards the chromatin. When cultivated in a full nutrient 
solution, the nucleus became much denser in its staining 
properties and somewhat enlarged, while when the cultiva- 
tion was carried on in a solution free from phosphorus the 
opposite was sure to occur. The central body, of the forms 
of Nostoc that grow in Collema, or of Anabaena found in 
the roots of Cycas, is very much poorer in chromatin than 
is that of similar plants growing under their natural environ- 
