THE CYTOLOGY OF THE SUGARCANE 523 
Dr. DE Mot 4) found that this treatment causes in certain races of 
hyacinth abnormalities in the pollen, which do not occur in bulbs, not 
exposed to those high temperatures. As a consequence of these high 
temperatures there arose, besides normal pollengrains, fertile and sterile 
ones, which possessed 4, sometimes even 5—8 nuclei of the shape of 
vegetative nuclei. Besides these, very large pollengrains occurred with 
a vegetative and a generative nucleus, both much larger than those of 
normal fertile pollengrains. While the normal haploid chromosome- 
number is 8, a number which he found also in the multinuclear pollen, 
he found in the division-figures of the very large pollengrains more than 
10 chromosomes. He says, perhaps a little prematurely, : 
„L conclude from these observations, that the large, globular pollen- 
grains are diploid, that therefore their vegetative and generative nuclei 
are composed, just as the nuclei of the somatic cells of these varieties, 
of 16 chromosomes, 8 of which are long, 4 of which are of medium size 
and 4 of which are small” ?). He thinks it probable, that also in the case 
of the plants treated in an abnormal manner, a normal division of the 
pollen-mothercells has occurred and that this has given rise to the for- 
mation of normal tetrads with a haploid chromosome-number. Only 
after the pollengrains had been formed, stimuli should have acted, 
which cause the origin of an abnormal number of nuclei or of nuclei 
abnormal in size in them. Confirmation of this supposition, based on 
extensive cytological researches, both in the case of plants treated nor- 
mally and abnormally, is decidedly necessary. It is however certainly 
curious, that the cross of normally treated plants of one race with plants 
of another race which had been exposed to a high temperature, the 
latter serving as father in the cross, gave rise, besides to a large num- 
ber of diploid plants, to some triploid ones. Such did not occur in 
the case of a cross between parents, both of which had been treated 
normally. The researches of Dr. DE Mor consequently prove that 
high temperatures can have a great influence on the pollen-for- 
mation. 
ERNST expresses in his book ,,Bastardierung als Ursache der Apo- 
. gamie im Pflanzenreich”’ the opinion that hybridity should be the 
1) Dr. W. E. pe Mot. Duplication of generative nuclei by means of physiolo- 
gical stimuli and its significance. Genetica V. 1923 p. 226. 
*) ibid. p. 238. 
