320 BOTANICAL GAZETTE [OCTOBER 
membranes when not easily seen in the living cells were readily 
demonstrated by the use of methylene blue. 
The initiation of division is marked by the enlargement of the 
nucleus and the gathering of granules in a vertical plane about 
the nucleus in the short axis of the cell. A study of the nucleus 
at this stage reveals great variations in the appearance of the central 
body, the so-called nucleolus, and the surrounding part, nuclear- 
plasm. The periphery of the enveloping portion may consist of a 
fine network, the interstices of which are occupied by coarse or 
fine granules (fig. 5). Or in place of the granules a deeply stained 
but vacuolar material may form the junction of the threads (figs. 
1, 2, 4). This vacuolar-like material seen at the junction of the 
threads is in appearance like that seen in the chromosomes in late 
metaphase and anaphase. It also resembles that seen in Allium, 
for here the material is likewise thickened at the corners, suggesting 
four granules inclosing a vacuole. 
The central body may appear from the staining to be of uniform 
density (figs. 1, 2, 3), or it may be more or less vacuolar (fig. 4). 
In a later stage the central body may appear to disintegrate into 
deeply stained granules, while in the meantime the network becomes 
coarser and accumulations at the interstices of the deeply stained 
material more pronounced. This at times may consist of filamen- 
tous (fig. 3) instead of granular or vacuolar masses, hence tending 
to support GrEGorrE’s view (8) that there is no strict morphological 
distinction between chromatic granules and an achromatic sub- 
stratum, and that in nuclei both an alveolar and reticular structure 
may obtain. These variations are due doubtless, as D1GBY (5 
Suggests in Galtonia, to the colloidal nature of the chromatic 
substance. 
As the central body disintegrates (fig. 6), the space about it 
becomes gradually clearer, coincident with the expansion of the 
central mass which now occupies several times the original space. 
The fact that the space previously occupied by the network becomes 
clear, leads to the conclusion that network and nucleolus have 
become centralized in the spherical mass (figs. 7 and 8) now con 
sisting of granules and filaments of varying dimensions irregu- 
larly disposed. All observers of nuclear division in Spirogyra are 
