1292 
cotyledons. Mirsuck (1902) observed 3 nuclei, J vegetative and 2 
generative in Ruppia rostellata Koch. Scnürnorr (1919) describes 
explicitly the mechanism of division in the generative nucleus of 
Sagittaria sagittifolia. 
In germinated pollengrains of Monocotyledons more than 2 gene- 
rative nuclei have sometimes been observed. Thus STRASBURGER 
(1884) saw 4 of them in the pollen-tubes of Ornithogalum and of 
Scilla. Tams (1901) caused ripe pollengrains of Scilla sibrica to 
germinate in a 5°/, solution of cane-sugar and says: “ausnahmsweise 
wurden in einem gekeimten Pollenkorn 5 Kerne beobachtet”. 
In hyacinch-varieties, too, one may observe under particular cir- 
cumstances, that they contain pollengrains with 2 generative nuclei. 
I found them ia. in the single-flowered white variety La Neige. 
The vegetative nucleus was large and round. The exine of the pollen- 
grains was very transparent here, the wartlike protuberences were 
almost entirely absent. This made it possible to observe the nuclei 
closely, without having to colour them green first in a drop of 
methylgreen acid of vinegar. Not nearly all pollengrains possessed 2 
generative nuclei. That I ascribe the early division of the genera- 
tive nucleus to external circumstances, may appear later on. 
HL Further particulars concerning the occurrence 
of pollengrains with several nuclei in 
Dutch hyacinth-varieties. 
By way of introduction 1 mentioned that I found pollengrains 
with several nuclei in the variety Nimrod. When composing my 
extensive tables, 1 indicated not only the percentage of sterility, but 
also the origin of the racemes, the latter by indicating each parti- 
cular category with a capital. Moreover | nearly always gave, with 
each numeration a short description of the habitus of the pollengrains. 
In this contribution I think it sufficient to take out of the tables in 
question those varieties in which 1 found 7 the closed anthers pollen- 
grains, germinated with abnormal pollen-tubes, in which lay several 
nuclei. At the same time I mention the other numerations, bearing 
on the same varieties, but in which no pollengrains with abnormal 
tubes were found. Because NEMmrc (1898), as I said before, observed 
before me in the pollen of double-flowered hyacinths the same phe- 
nomenon, shall henceforth indicate it, in his honour, by the name: 
‘“Nemec’s phenomenon’. In so far as l have fixed the number of 
chromosomes of the varieties named below, | shall mention this. 
