238 DUPLICATION OF GENERATIVE NUCLEI BY MEANS OF 
had often a strikingly large circumference. Not rarely the nuclei were 
separated from one another by considerable. intervals. When 4 nuclei 
were present, one was sometimes lying at some distance from the three 
other ones and was larger than these. Such a large nucleus frequently 
was lying in the endpart of the pollentube, while the other, somewhat 
smaller ones, had remained in the pollengrain or had only just entered 
into the pollen tube. 
Not only sterile pollengrains were seen everywhere between these 
plurinuclear ones, but they were also accompanied by the large globu- 
lar pollengrains full of starch. The study of the latter especially was 
favored by the mikrotome-sections, as the starch grains no longer hid 
the other contents so completely from view as in the living grains. It 
could now distinctly be seen, that these pollengrains resembled, as far 
as their contents were concerned, most closely the normal fertile grains. 
Just as these, they contained.a globular, vegetative, and an ellipsoidal 
generative nucleus. The similarity was strengthened by the differences 
. In depth of staining, caused by the laxity of the chromatine and by the 
proportion between the longitudinal axis and the short ones of the ge- 
nerative nucleus, as well as by the presence of a spherically curved wall 
between the two nuclei present. Sometimes 2 generative nuclei were 
observed. 
Two points of considerable difference must however be mentioned. 
In the first place, as has been said already, these pollengrains had a glo- 
bular shape while normal fertile grains are ellipsoidal. They were also 
much larger than the latter, in connexion with which, as could clearly 
be seen now, the vegetative nucleus and the generative one — the com- 
pactness of the chromatine of which, as was shown by the depth of 
staining, was comparable to that of the nuclei of the normal fertile pol- 
lengrains — reached approximately a volume twice as large as that of 
the normal generative and vegetative nuclei. The globular, vegetative, 
nucleus was best comparable, as far as its size was concerned, with the 
nuclei, occuring in the cells of the roottips of diploid varieties of Hya- 
“cinthus orientalis. I have not succeeded in determining the number of 
chromosomes in division stages of these nuclei, but it could be made 
out with certainty that it was superior to 10. When in the plurinuclear 
pollengrains a globular nucleus divided, it showed its composition out 
of 8 chromosomes. J conclude from these observations, that the large, glo- 
bular pollengrains are diploid, that therefore, their vegetative and genera- 
a inl 
