1913] MERRIMAN—SPIROGYRA 321 
practically unanimous in the view that the nucleolus is partly or 
wholly transformed into the substance of the spindle; the dis- 
agreement is as to whether the network furnishes any of that 
substance. The chromatic nature of this network is shown in 
figs. 2 and 3. 
The nuclear membrane still intact shows that as yet none of 
the bodies previously seen in the space has been cast into the cyto- 
plasm, unless in solutes by diffusion. This was confirmed by the 
study of whole mounts (fig. 8). Hence we may conclude that the 
enlargement of the central mass is due to the inclusion of the 
substances of the network, all now showing an increased staining 
capacity. It is possible, as in fig. 6, where short filaments are seen 
distributed throughout the nucleus and superimposed on the cen- 
tral mass, that the latter as it disintegrates only contributes the 
granular material to the spindle. 
With the enlargement of the central mass the evolution of the 
spindle proceeds. The suspensors increase in size, while streams 
of granules appear to penetrate the nuclear membrane and connect 
with the centrally lying mass (fig. 7). These later increase as the 
mass of chromatic material changes its shape from that of a sphere 
(figs. 6-8) to a cylinder (figs. 13-16). Now the streams of gran- 
ules appear to cause the cylinder to swing so as to lie with its long 
axis parallel with the long axis of the cell. In the fully developed 
spindle nothing of a fibrous nature is to be perceived but lines of 
granules staining as the cytoplasm, and so always distinguished 
from the equatorial mass. These lines of granules terminate in 
granular masses not linearly arranged. The masses are later seen 
to envelop the daughter nuclei (figs. 34, 36). 
In sections of late prophase two kinds of material, one staining 
more deeply than the other, can be seen occupying the nuclear space, 
the nuclear membrane still visible. The more deeply stained ma- 
terial is in the form of short filaments (fig. 12) or lumplike masses 
(figs. 13, 15). The chromatic material here with its dumbbell- 
shaped (figs. 13, 19, 20) or somewhat elongated granules often 
resembles that seen in precipitates secured by FiscHeR when nuclein 
acid is precipitated with Flemming and chromic acid mixtures 
(7, p. 43). Also they may be reasonably compared with those in 
