255. 
Researches into the dying-off of pollen-grains after the reduction- 
division in the hyacinth have taught me, that this is most likely 
due to the fact that the protoplasm present, is too small for such 
large pollen-grains as King of the Blues and Queen of the Pinks 
possess. Now it seems to me that the greater fertility of dwarfn’. 1 
is directly related to the quantum of protoplasm at its disposal, 
which will probably be sufficient for its smaller pollengrains. I 
have not yet been in a position to examine the fertility of the 
22d dwarf. 
In the literature I know of no instances of dwarf-forms among 
the higher plants, arisen through somatic variation, that can be 
differentiated cytologically. It is an unshakable fact, that these 
dwarfs descend from King of the Blues, but particulars about 
the true cause of these dwarf-plants are still lacking. First 
of all the injuries evolved by crucial incisions might be made 
answerable for it. The interpretation of the observed phenomena 
would then accord with the opinion of Sakamura (1920), that no 
autoregulative reduction of the chromosomes in somatic hyperchro- 
mosomal cells takes place. Secondly the cause might be looked for 
in the fact, that the mother-plant is triploid; this may induce 
something like a regulating process, which, when telling to full 
advantage, would result in the diploid condition. 
In that case the phenomena, appearing with the nucleus-division 
in the soma of the plant, would run parallel with those occurring 
with the heterotypical division of the pollen parent-cells. I refer to 
my description of the reduction-division of the 27-chromosomal 
variety J.’ Innocence. 
When assuming moreover with WinkrerR (1916 page 522), that 
according as the number of chromosomes exceeds more and more 
the diploid number, the chances of disturbances in the process of 
the somatic nucleus-division will increase, then there is besides the 
reason mentioned in my publication “Nieuwe banen, etc.”, still another 
argument that justifies my warning not to go on exterminating the 
old, valuable diploid Dutch hyacinth-varieties. 
It seems probable to me that dwarf-hyacinths occur not unfre- 
quently through somatic variation of heteroploid species, but that 
they are generally not observed, or are thrown away as being 
unfit for cultivation. .I know for certain that from the heteroploid 
pink-coloured variety Moreno a darker dwarf-form is derived, which 
however got lost before I was able to examine it. About six years 
ago a variegated plant was derived from the heteroploid variety 
Queen of the Blues. The bulb of this plant (which is in my possession) 
Eire 
