272 Phillips on a Comparative Study of the 
loosely imbedded small granules, each of which stained deeply 
with the ordinary (basic) nuclear stains after having been 
properly fixed with sulphuric acid. These granules, from 
their behavior during division and towards stains and chem- 
ical reagents, were identical with the chromatin substance of 
the cell nuclei of higher plants and animals, and on this 
account were designated “chromatin granules.” They had 
no relation to the peripherally lying albuminous crystalloids 
or to the slime vacuoles, and they never appeared isolated 
in the peripheral protoplasm. They were therefore neither 
identical with the slime balls of Palla nor with the “red 
granules” of Butschli. (17) The nuclei of the Cyanophycez 
differed from the nuclei of the higher organisms by their 
lack of nucleoli and the absence of any nuclear membrane. 
A sharp differentiation of the nucleus could be obtained by 
fixing with sulphuric acid and staining with Heidenhein’s 
iron-alum hematoxylin. (18) During division of the cell, 
the small chromatin granules merged into one another and 
formed larger masses whose chromosome nature could easily 
be demonstrated from their behavior during division. Their 
identity could also be traced into the daughter nuclei. (19) 
As the chromosomes drew apart and took up their positions 
at the poles of the dividing spindle, there could, in every 
case, be made out a zone of delicate non-granular fibers 
(striated zone) connecting the daughter nuclei. These repre- 
sented the central fibers of the achromatic spindle of higher 
plants. (20) The nuclear division was carried on entirely 
independent of the cell-plate formation, and was completed, 
or nearly so, before it had begun to grow in as a collar-like 
ingrowth from the equator of the mother cell. The ingrow- 
ing cell-plate slowly advanced until it forced the fibers of the 
spindle together into a thin thread or cord which pierced the 
cell-plate in the centre. This achromatic thread was finally 
severed, but the cells remained connected by a pore from 
one cell lumen to the other. (21) The polar movements of 
the chromatin substance and the formation of a chromatic 
