Cytology and Movements of the Cyanophycee. 269 
mitotic division was merely made up of aggregated crystal- 
loids. Division was accomplished by an ingrowth of the wall, 
which cut the chromatophore and then the central body, but 
the central body itself did not, pari passu, begin to divide as 
in direct division of the higher plant nucleus. It was merely 
constricted by the ingrowing peripheral wall until a slight 
tag of protoplasm remained to connect the halves. This 
finally separated and division was complete. The central 
body was vacuolated and the pressure of these vacuoles 
caused the granules of the central body to become heaped 
up. Concerning the bacteria, Fischer considered the claim 
that they absorbed nuclear stains to be a myth. The cen- 
tral body described by Butschli as having clear ends he con- 
sidered to be nothing more than the plasmolized protoplast. 
He found in these organisms, within the cell wall, first a 
protoplasmic wall-facing that surrounded a sap vacuole. A 
nucleus was not to be seen, the colored granules being 
reserve food material within the cell. The relation of the 
sulphur and other bacteria to the Cyanophyceze was very 
loose and mostly morphological. 
Probably the most exhaustive work that has yet appeared, 
and certainly the one which commanded greatest interest 
on account of the advanced ground taken was by Robert 
Hegler (38). The conclusions drawn in this article were 
so far-reaching, and in many respects so exhaustive, that it 
seems best to give his results at some length, substantially 
as summed up by himself in his concluding remarks, though 
adding some points to make them more clearly understood. 
(1) The cells of the Cyanophycee are in all cases sur- 
rounded by a cell membrane of peculiar material, distinct 
from the sheath, which latter is identical with the capsule of 
the encapsulated bacteria. Naked cells do not appear in 
these plants. The hormogonia do not possess a demon- 
strable membrane. (2) The gelatin coverings and the 
sheaths are the products of the membranous walls. The 
sheaths as well as cell membranes have a marked power of 
