228 DUPLICATION OF GENERATIVE NUCLEI BY MEANS OF 
and SON at Hillegom (Leeuwenstein) ; furthermore 7 bulbs of the va- 
riety Yellow Hammer (Yellow Hammer n. N.) obtained from the firm 
P. NELIS and son at Heemstede, while in addition were planted 2 
bulbs of the variety Homerus (Homerus n. D.) bred by MR. CHR. Dors 
at Voorhout. 
None of these bulbs had been exposed to abnormal conditions. Be- 
sides these, were planted: 
10 bulbs of the variety Yellow Hammer (Yellow Hammer abn. N.), 
also bred by the firm P. NELIS and SON, already mentioned; these 
bulbs had been taken up on the 14th of June 1920, in unripe condition 
e.g. while the leaves were still green ; subsequently they had been expo- 
sed, during two weeks, to a temperature, oscillating between 82° and 
87° F.; followed by exposure, during two weeks also, to a temperature 
between 78° and 82°F., and afterwards, during 3 weeks, to a temperature 
as Close to 70° F. as possible; after treatment the bulbs were kept, up to 
the time of planting, in a dry locality which was not heated artificially. 
Finally 10 bulbs were planted of the variety Yellow Hammer (Yel- 
low Hammer abn. W.) procured from the breeder J. WIEDEMEYER at 
Hillegom, which — like the last mentioned bulbs of the firm NELIs — 
had also been taken up in unripe condition on the 14th of June 1920; 
these were, during the first subsequent two weeks, not exposed to any 
unusual temperature, but put to dry in the upper story of a bulb-hou- 
se; from the Ist of July to the 20th of that month, they were heated up 
to 65° to 70° F., subsequently this heating was suspended until the 10th 
of August; after that they were again exposed, during a period of two 
weeks, to a temperature of 70° F.; while finally they were treated like 
the former ones. 
All bulbs were planted singly in pots; the pots were dug into the soil, 
and covered by a layer of turfdust, to protect them against night- 
frosts. When, in March 1921, the flowerbuds had developed so far that 
the flowers began to move apart, and that that part of the flower stem, 
which is situated below the flowers, began to appear, the pots were ta- 
ken from the soil and placed in a room, from which, during the time 
that the experiment lasted, all other kinds of hyacinth-flowers were 
severely banished. Each inflorescence was isolated by a bag of parch- 
.mentpaper. Just before the thecae began to rupture, that part of the 
perigonal tube, on the inside of which the filaments of tHe stamina are 
inserted, was cut off. | 
ii 
