244 DUPLICATION OF GENERATIVE NUCLEI BY MEANS OF 
pots against dessiccation and the seedlings against the attacks of in- 
sects, the pots were put in low boxes filled with river-sand. These boxes 
were put in a moderate hotbed, the temperature of which was kept 
just above the freezingpoint. 
On the 5th of January 1922 more than 20 seedlings ee already 
above the soil. Whenever, subsequently, 20 to 30 seedlings appeared, 
fixation in Flemming took place. To this end the stem was always se- 
parated from the roots and all roots and a number of stems were fixed 
and subsequently embedded in paraffine. Sedlings theroottips of which 
had been cut off, but the seed and the nonfixed parts of which had re- 
mained intact, were planted again to see whether they were able to con- 
tinue to grow. This was the reason why I did not sprout the seeds in a 
simpler way, for instance in Petri-dishes, by which method an equally 
large number of seedlings might have been obtained, but which would 
probably have produced less vigorous seedlings. In this way I succeeded 
in keeping 62 plants alive; it need not be said that the keeping alive 
of the investigated seedlings can be of considerable importance. Lack 
of leasure forced us to postpone the cutting of the sections and their in- 
vestigation. In Dec. 1922 and January 1923 the investigation was con- 
tinued, my wife again kindly making most of the preparations, while 
a preliminary investigation of them was partly made by Miss M. W. 
SCHUTTE. 
Now, in May 1923, preparations of 160 roots have been made and in- 
vestigated. THREE!) OF THEM CONTAINED TRIPLOID NUCLEI, ALL FROM 
THE CROSS Gertrude n. V. W. L. 2 x Yellow Hammer abn. W. &. 
In 2 of these roots it was clearly seen, that of the 24 chromosomes, 
12 were long, 6 of medium size and 6 short. Of by far the greater number 
of the 157 other roots it could be established that the nuclei were di- 
ploid, e.g. that they contained 16 chromosomes of which 8 were long, _ 
4 of medium size and 4 short. It need not be said, that it is not easy, 
to determine this in all cases, after investigation of 30 to 40 transverse- 
sections of 20 u, together forming the division-zone of the roots. 
In cases where no certainty could be obtained, the seedlings were 
counted as diploid ones. I felt justified to-do this, the more so as I 
found that the nucleoli are reliable guides in the determination of the di- 
1) After this had been written a 4th and 5th triploid has been found, showing 
distinctly 24 chromosomes, 12 of which are long, 6 have medium size and 6 are 
short. 
RATÉ 
