292 DUPLICATION OF GENERATIVE NUCLEI BY MEANS OF 
the case of the hyacinth, also where the pollentubes of the former have 
a much smaller diameter than those of the latter. 
d. When we observe the peculiarities of plurinuclear haploid pollen- 
grains [ 1°. formation of a bladderlike pollentube ; 2°. presence of globu- 
lar nuclei; 3°. absence of generative cells ;] in a phylogenetic light, we 
will find no reason to suppose that they should be unable to function in 
fertilisation. 
Bladdershaped pollen-tubes are met with in Dioon, Zamia, Ginkgo 
Picea etc. Generative nuclei are frequently globular, and their chro- 
matine as little compact as that of vegetative nuclei, in the case of 
Pteridophytes and Gymnosperms. Sometimes the generative nuclei ap- 
proach more closely the shape of a globe than the vegetative ones (Cf. 
LAND's figure of Ephedra trifurca). Such may also be the case among 
Liliaceae. The spermnuclei of Lilium Martagon, which are enclosed in 
generative cells, have a more globular shape than the vegetative nuclei 
(cf. the figures of GUIGNARD and CHAMBERLAIN). The cross L’ Espé- 
vance 2 X L’ Innocence & has shown (1922a) that large pollentubes of 
hyacinths are able to grow through the tissue of stigma and style of 
small diploid varieties. 
e. It was suggested to me, by one who considers the Monocotyledons 
more closely related to the Gymnosperms than the Dicotyledons, that 
the similarity of part of the abnormal pollengrains of Hyacinthus orien- 
talis to those of the Gymnosperms is due to their close phylogenetic 
connexion and suggests rather that duplication of generative nuclei be 
limited to Monocotyledons, a conclusion which would considerably di- 
minish the value of the phenomenon in connexion with the perspectives it 
opens for the breeding of new varieties of plants. We know already some 
facts, however, which do not support such a view. Sakamura (1920) was 
able to determine, that pollengrains with several nuclei or with very 
large nuclei were present in flowers of Vicia Faba which had been cove- 
red by snow. His textfigure 23 pictures large pollengrains with a gigan- 
tic spindleshaped generative nucleus, which remind us strongly of the 
abnormal pollengrains of Hyacinthus. (Cf. further his textfigures 21 and 
22 and his figures 160 and 161). On p. 141—142 he says: , Ausser diesen 
(other aberrations) werden häufiger ein diploider oder zwei haploide 
Kerne aus den zwei Teilungsfiguren in einer Tochterzelle rekonstru- 
iert”. Of Allium Cepa one has also obtained similar pollengrains. „sie 
sind natürlich durch abnorme homotypische Kernteilung entstanden, 
