Pinus silvestris. 
3i 
the wall of an archegonium of which 3 have 12 chromosomes 
and one 24. In some cases too 8 were found. This led me 
to examine the youngest endosperms I had at my disposal, 
i. e. of April 24, and I found that there is in these a group 
of larger nuclei at the upper end of the embryo-sac which 
certainly, in some cases, have 12 chromosomes. At this 
stage the walls of the archegonium were not yet formed by 
cells provided with membranes. In several specimens both of 
the early and later stages, where nuclei with a larger number 
of chromosomes were seen, it was possible also to find nuclei 
in the lower parts of the embryo-sac which had only 8 chromo- 
somes. Fig. 23 shows a nucleus from an endosperm of this 
date with 12 chromosomes. Accordingly it appears that, even 
in a comparatively early stage of its development, the gameto- 
phyte is composed of two distinct kinds of cells, i. e. those with 
nuclei containing 8 chromosomes and those whose nuclei have 
12 or 24 chromosomes. To which of these kinds does the 
oosphere belong ? As is well known the oosphere divides 
shortly before fertilization to give rise to the ventral canal-cell ; 
so this would seem to be a suitable time to count the chromo- 
somes of its nucleus. However, although I found this division 
very frequently, I never succeeded in counting the chromosomes 
of its nuclear plate, owing to the very minute quantity of 
chromatin present and the consequent difficulty in staining 
(Fig. 24). Strangely enough, however, the chromosomes of the 
ventral canal-cell arising from this division remain for some 
time separate from one another. Fig. 25 is a drawing 
of the cell in this state, and shows that it contains only 8 
chromosomes. I counted this number in two other specimens 
also. From this we may conclude that as the canal-cell 
arises by karyokinesis from the oosphere and as the former 
has 8 chromosomes, so the oosphere has 8. As the chromo- 
somes during this division could not be counted, it is not 
certain that the number in the oosphere is 8, more especially 
as Prof. Strasburger 1 counted 12 chromosomes in the nuclei 
of the pollen-grain. 
1 Ueb. das Verhalten d. Pollens; Hist. Beitr., IV, 1892. 
