2 37 
Life-History of Isoetes. 
but evident membrane, and usually one large nucleolus. This 
stains somewhat with gentian-violet and safranine, but not 
very deeply: and while a faint reticulate structure may be 
seen, it does not stain. The nucleus of the resting spore, it 
will thus be seen, is very poor in chromatin. 
In my preliminary paper 1 , the statement was made that 
the nucleolus, even in the ungerminated spore, stains strongly, 
but a further examination of the preparations showed that 
this was only true in spores that had been free for some time, 
and indicated, presumably, the first stage in their germina- 
tions. A number of spores taken directly from the sporangium 
and sectioned, showed but very slight coloration of the 
nucleolus. 
After the spores have lain a few days in water, the nucleus 
increases somewhat in size, and then the nucleolus colours very 
intensely. At the same time several smaller bodies, likewise 
strongly coloured, and resembling the nucleolus except in size, 
are usually to be seen (Figs. 4, 5 )« In these nuclei, too, there 
is a central area that colours faintly, and later (Figs. 4 and 5), 
in this area the nuclear filaments can be seen, and small 
chromatin-corpuscles become visible. 
Although a large number of sections were made, the further 
changes in the nucleus, preliminary to its division, were not 
seen, and only twice was the primary nucleus of the spore 
found in actual division, in both cases nineteen days after the 
spores were sown. In the younger of the two the chromatin- 
masses were distinct and in the form of nearly round granules. 
The outlines of the daughter-nuclei could be faintly traced, 
but no membrane had yet formed. Very numerous connect- 
ing threads were seen between the young nuclei, and a very 
evident cell-plate occupied the equator of the nuclear figure. 
The older stage (Fig. 6) had the membrane of the daughter- 
nuclei better defined, and the chromatin-masses had apparently 
partially coalesced. No cell-wall is formed, and the result 
of the first division is two free nuclei. The first division takes 
place while the nucleus is in its original position, but whether 
1 Loc. cit., p. 99. 
