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PHYSIOLOGICAL STIMULI AND ITS SIGNIFICANCE 247 
There is no doubt, that it was of great importance to be able to settle 
with certainty that the seedlings with 24 chromosomes were really tri- 
ploid e.g. possessed 12 long chromosomes, 6 of medium size and 6 
short ones, as it is extremely improbable that such should be the result 
of pollination with a pollengrain of a heteroploid variety. As great 
exactness was required, the seeds, destined to be sown were carefully 
kept apart. They were collected from the dry inflorescences, put in Pe- 
tri-dishes and kept in a dry room under lock and key. 
When a seed fell to the ground, it was destroyed. Of 5 seeds, the 
motherplant could not be ascertained, of 26 other ones, I was 
uncertain as to the kind of pollination to wich they owed their 
origin. These 31 seeds have been sown, but have not been inserted 
in the table. 
The precautions taken, strenghten my conviction, that the 3 triploid 
plants originated in consequence of pollination, with pollengrains, the nu- 
clei of which, had purposely been duplicated. : 
VIII. REMARKS ABOUT THE PRECEEDING CHAPTERS, IN CONNEXION 
WITH SOME FACTS KNOWN FROM THE LITTERATURE 
We should like to state, that we are fully aware that this publication 
puts us under the obligation to study more carefully the circumstances 
under which the physiological stimuli exert their influence, to inves- 
tigate more closely the cytology, especially of fertilisation-stages, and 
the way in which the abnormal pollengrains arise, as well as the beha- 
viour of contrôleplants. 
The chiefpoint however, in our opinion, is, that we succeeded to obtain 
duplication of generative nuclei by means of physiological stimuli and so 
opened the possibility to obtain triploid plants experimentally. We shall 
now proceed to the discussion of certain facts of special importance in 
connexion with our subject. 
a. Can the physiological stimuli have caused not only the production of 
diploid spermnuclei but also of diploid eggnucler ? 
We can only say, that a study of the ovules of the flowers, the an- 
thers of which had been examined microscopically, never revealed any 
abnormality, which, of course, is no definite and conclusive answer to 
the question put. It is however certain that the pollengrains of hyacin- 
thus are much more readily influenced by external circumstances than 
