234 DUPLICATION OF GENERATIVE NUCLEI BY MEANS OF 
IV. POLLINATION, FRUITING AND FORMATION OF THE SEED 
With the exception of a plant of Yellow Hammer abn. N., of 1 bulb of 
Yellow Hammer abn. W., of 10 specimens of Gertrude abn. N. and of two 
of Homerus, all the other plants flowered in the second half of 
March and in the first half of April 1921. Before and during pollination 
the investigation of the pollen, described in Chapter III, took place 
and also the fixing of the anthers destined for the cutting of mikro- 
tome-sections. 
The great degree of self-sterility which characterises the varieties of 
Hyacinthus orientalis (cf. 1922a) was not known to me at that time. 
Consequently selfing was not omitted: and I shall report the results he- 
re, for two reasons, 1°. because the proof of self-sterility already fur- 
nished in the publication mentioned, is strengthened by those results, 
2°. because they stow, that abnormal fertile pollengrains are unable 
to lessen the grade of self-sterility. 
a. The selfing of Gertrude. 
The flowers of the 10 inflorescences of Gertrude abn. N . were selfed, 
which was even repeated some times in the case of the lower flo- 
wers. | 
No seed was formed. 
b. The pollination of Homerus with Yellow Hammer. 
Of the two inflorescences of Homerus n. D. the flowers were polli- 
nated with pollen of Yellow Hammer abn. W. No seeds. 
c. The pollination of Gertrude with Yellow Hammer. 
The 13 inflorescences, which flowered on the 12 bulbs of Gertrude n. 
V. W.L. — one bulb made two inflorescences — were pollinated as 
follows: 
8 inflorescences with pollen of Yellow Hammer abn. W . with the 
restriction that of two inflorescences, half of the flowers — the up- 
per half — was selfed, this selfing producing no seeds. Three of the 
8 inflorescences developed fruits which gave respectively 198, 93 
and 21 ripe and apparently good seeds. The inflorescence producing 
but 21 seeds was one of the two which had partly been selfed. 
2 inflorescences, pollinated with Yellow Hammer abn. N. gave 428 
probably good seeds. 
2 inflorescences, pollinated with Yellow Hammer n. N. gave respec- 
tively 358 and 90 apparently good seeds. 

