PHYSIOLOGICAL STIMULI AND ITS SIGNIFICANCE 227 
Général Pélissier, diploid. 
Yellow Hammer, diploid. 
Marchioness of Lorne, diploid. 
Lady Derby, triploid. 
Nimrod with 19 chromosomes in the somatic cells. 
City of Haarlem with 23 chromosomes. 
Charles Dickens 
Moreno ( 
King of the Yellows ] 
and in the case of 4 varieties with double flowers, to wit: 
Van Speyk with 21 chromosomes. 
La Virginité | 
Noble par Mérite 
Blocksberg | 
In February 1921 the aberrant pollen of the diploid variety Yellow 
Hammer was used for selfing and for the pollination of the diploid va- 
riety Gertrude with single flowers, which had been cultivated under 
normal external conditions. 
The latter pollinations produced some descendants, which in contrast to 
the DIPLOID parents, were TRIPLOID. 
It was this fact, which made me pronounce the hope that further 
| number of chromosomes not yet exactly de- 
termined. 
number of chromosomes not yet investigated. 
facts would come to light. 
II. ORIGIN OF THE MATERIAL USED IN THE EXPERIMENTS, AND ITS 
TREATMENT UP TO THE TIME OF FLOWERING 
It is, in connexion with our subject, of importance not only to know, 
but to see at a glance of the varieties mentioned in the experiments: 
1°. whether they were cultivated under normal or under abnormal con- 
ditions ; this will be indicated by #. and abn. respectively ;2°. their or1- 
gin; this will be indicated by the initials of the names of the firms from 
which they were obtained. 
The following example may show how these designations will be 
used throughout the text: 
On the 15th of September 1920 were planted: 
12 bulbs of the variety Gertrude (Gertrude n. V. W. L.) and 5 of the 
variety Yellow Hammer (Yellow Hammer n V.W.L.) which therefore 
means, that these bulbs had been bred by the firm M. VAN WAVEREN 
