Cytology and Movements of the Cyanophycee. 247 
dividing nucleus. This was considered to be a nucleus 
because it broke up into a number of pieces and the cell then 
divided, the ingrowing division wall being plainly seen. 
Between the daughter nuclei he could further distinguish, 
in some cases quite distinctly, fine colorless striz which sug- 
gested the achromatic fibers of karyokinesis. 
Probably the most extensive worker on the Cyanophycez 
was E. Zacharias, to whom we owe much in the solution of 
the cytological problems, not only of these but of all organ- 
isms. His researches covered not merely the staining rela- 
tions of the different parts of the cell, but included an 
exhaustive micro-chemical study, and it is for this portion of 
his work that we owe him greatest thanks. His first inves- 
tigation (88) published in 1887, was on Tolypothrix and 
Oscillaria and his methods and conclusions might be 
summed up as follows: First. Fresh material treated with 
gastric juice, was extracted with ether and alcohol, fol- 
lowed by 0.3 per cent. hydrochloric acid. The granules gave 
the characteristic “nuclein luster.” Second. In material 
treated as above, followed by Io per cent. sodium chloride 
or with 0.05 per cent. potassium hydrate the “central sub- 
stance” disappeared. Third. Fresh threads treated with 55 
per cent. hydrochloric acid caused the “central substance” 
to swell. These considerations caused him to conclude that 
the “central substance” was a nucleus. 
In a later work, Zacharias (89) extended his studies to 
include, besides the former organisms, Nostoc, Tolypothrix, 
Cylindrospermum and Scytonema. It was in this work that 
he took up the micro-chemistry most fully. He found a 
colored peripheral layer, often thickest on the partition walls, 
which he thought was ‘surrounded by a thin uncolored 
plasma layer, and a central part which always remained 
clear. He could not determine whether the colored portion 
was to be regarded as a chromatophore or not. In the cen- 
tral part he saw many granular frame-like formations and 
one or two nucleolar-like bodies, though they were not pres- 
