266 
12. 
DUPLICATION OF GENERATIVE NUCLEI BY MEANS OF 
stimuli; and consequently towards the formation of abnormal, 
fertile pollengrains. 
Pollination of the diploid variety Gertrude with pollen of the diploid 
variety Yellow Hammer, the majority of which was abnormal, in 
the way described, gave — as for as the investigation was pushed 
forward — 5 triploid seedlings among numerous diploid ones. 
We are of opinion that these triploid seedlings, owe their origin, in 
the first instance, to duplication of male sexual nuclei. 
If this opinion should prove to be right, if therefore triploidy can 
be made to appear experimentally by purposely obtained dupli- 
cation of sexual nuclei, an important perspective is opened in con- 
nexion with the amelioration of cultivated plants. (Pluriploid or- 
ganisms can attain greater size etc.). Also for the question of heri- 
dity. (The phenomenon is perhaps not limited to heterozygous 
plants; if it also occurs among homozygotes we would be able to 
compare diploid and triploid plants which have derived the same 
properties from their mother as from their father; as in the latter 
case the properties of the father are present in a double dose, it can 
be studied, whether this influences dominance or recessiveness. As 
furthermore, the reduction division proceeds in an irregular 
manner in triploid plants, we get the possibility to compare the 
descendants with different chromosome-numbers with one ano- 
ther; a happy choce of the plant submitted to the experiment, 
may then throw light on the role of each individual chromosome 
BEC) 
. Dutch breeders of hyacinths have unconsciously applied the same 
principle, in the course of the centuries, as we applied in our ex- 
periments to obtain duplication of sexual nuclei because they fa- 
vored, by the harvesting of the bulbs in an unripe condition, or by 
the cutting off of their leaves, the earlier beginning of the period of 
flower-formation and its acceleration and as a consequence of this 
the production of duplicate sexual nuclei. 
Consequently triploid varieties have appeared both with the bree- 
ders and in our experiments. 
Hybridisation with these triploid forms has gradually caused the 
large and firm forms of present day hyacinths, to appear in the 
cultivations. 
We have good reasons to believe that the gigantic magnicoronate 
