116 
Arlow Burdette Stout 
Plerome, periblem and dermatogen, and calyptrogen are sharply 
delimitcd in the roots of Carex aquatüis and the lines of demarcation 
are even carried through the embryonic apex of the root. The resting 
nuc-lei of all these regions show the structiire described above. I have 
drawn a gronp of cells from the center of the embryonic region to show 
this (fig. 4). Cells a and b belong to the plerome, c and d to the periblem 
and dermatogen, and e is a cell of the calyptrogen. These are typical 
resting cells of the embryonic region. 
That the chromatin masses which are present in these nuclei are 
the indi'vndual chromosomes is e-\ädent from a study of their subsequent 
history and appearance in the di\’ision figures. In shape they are sonie- 
what irregulär but compact masses entirely similar to the chromosomes 
as they appear in the middle prophases of the somatic divisions. In 
careful counts in a large number of resting nuclei I have in no case foimd 
more of these masses than the number of diploid chromosomes. The 
number established by counts of the equatorial plates of somatic, heterc- 
typic, and homoeotypic division figures is, as near as I can determine, 
seventy-four. The chromatin units in the resting nuclei are small and 
often two or three of them are more or less massed together or overlie 
each other so that it is not possible to count them vdth complete cer- 
tainly. It is clear, however, that their number does not exceed that 
of the chromosomes appearing in the equatorial plate. 
The preparation shown in figure 4 is characteristic in this particular. 
The entire nucleus of cell c is present in the section and in it nearly sc- 
venty indi%ndual chromatin bodies are visible. Parts of the other nuclei 
drawn did not show in the section. Of the nuclei b and e about one-half 
is shown and forty-two chromatin units appear. Larger portions of the 
nuclei a and cl are shown with a proportionally greater number of chro- 
matin masses. 
As noted above, a most conspicuous and interesting feature of the 
resting nuclei is the arrangement of the chromatin masses in series. It 
is not entirely clear that there is a single continuous spirem at this stage, 
but as is clearly shown in the drawing, in various regions of a nucleus 
a series can be traced for some distance. "Wliere two series cross or are 
massed together it is difficult to trace the line. Cross fibres from one 
series to another may be present, but they are secondary. In these rest- 
ing nuclei the chromosomes are definite bead-shaped bodies connected 
by rather thin Strands of linin. ’Wlien closely placed the series is easily 
traced; where the individuals are farther apart the connecting linin 
Strands are followed with more difficulty. 
