
PHYSIOLOGICAL STIMULI AND ITS SIGNIFICANCE 243 
vegetative one, but this supposition does not seem so logical to me as 
the other one. 
Also, on the ground of a rather extensive study of the reduction-di- 
vision of the pollenmothercells of the hyacinth-varieties: 
Marchioness of Lorne (diploid), 
Grand Mattre (triploid), 
and L’ Innocence with 27 chromosomes in its somatic cells, I am now 
of opinion, that the abnormal pollengrains arose in the way first sug- 
gested. 
The plants, namely, the reduction-division of which was investiga- 
ted, were purposely submitted to about the same abnormal circum- 
stances as Yellow Hammer abn. N. and abn. W. I have never been able 
to find irregularities, occuring during the different phases of the reduc- 
tion-division, for which, in my opinion, the abnormal treatment of the 
plants could be held responsible. The impedements in the heterotype 
division of the investigated heteroploid varieties during anaphase (cf. 
what has been said of the reduction division of L’ Innocence in the pu- 
blication 1920a and 1921a) occur both in the case of normally and ab- 
normally treated plants. 
The abnormalities which occurred after the formation of the tetrad 
cells, both in the diploid variety Marchioness of Lorne and in the hete- 
roploid varieties Grand Maitre and L’Innocence, were due, when not 
entirely, at least partly, to the abnormal treatment. 
VII. THE TREATMENT OF THE SEEDS AND THE CYTOLOGICAL 
INVESTIGATION OF THE SEEDLINGS. 
After having thus obtained, purposely, plurinuclear haploid pollen- 
grains and diploid pollengrains, and after having pollinated with pollen 
containing these abnormal grains in excess or in a minority, as well as 
with pollen not containing them, the first work to do was to sprout 
the seeds and to study the somatic cells of the seedlings cytologically 
with the view to determine their chromosomenumber. This might allow 
us toconlude, with some considerable degree of probability, whether we 
are able to force diploid parentplants to produce pluriploid descendants 
and if so, to which degree. | 
To this end, de seeds harvested in May and June were sown Oct. 
19. 1921 in small flowerpots, 5 seeds in each. To protect the soil of the 
