1302 
experiments it has now, on the 3rd February, become evident to me 
that it is possible, to cause the growth of pollen-grains that exhibit 
Nemec’s phenomenon. To the great importance of deliberately produ- 
cing pollen-grains with more than one nucleus — also SAKAMURA 
(1920, p. 145) by his discovery of several nuclei in the pollen- 
grains of Allium Cepa has come to the opinion that they owe their 
origin to a modification of the exterior conditions of life — I hope 
shortly to draw attention. 
The diagrams 1 and 2 picture forth the pollen-grains of the variety 
Yellow Hammer, as I found them now in all anthers of the plants 
which are exposed to the same particular exterior circumstances. 
REFERENCES. 
CHAMBERLAIN, Cu. J., Contribution to the life history of Lilium philadelphi- 
cum (The pollengrain), Bot. Gaz,, 23, 1897. 
ELFVING, Fr, Studien über die Pollenkörner der Angtospermen, Jenaische 
Zeitschr. f. Naturwiss., 13, 1878. 
Gorinski, Ein Beitrag zur Entwicklungsgeschichte des Androeceums und 
des Gynaeceums der Grédser, Bot. Centralbl., 55, 1893. 
GUIGNARD, L., Le développement du pollen et la réduction chromatique 
dans le Najas major, Arch. d’anat. microsc., II, 1899. 
Murseck, Sv., Ueber die Embryologie von Ruppia rostellata Koch. K. Sv. 
Vetensk. Handl., 36, 1902. 
Nemec, B., Ueber den Pollen der petaloiden Antheren von Hyacinthus 
orientalis L., Academie des Sciences de |’Empereur Francois Joseph I, V, 
Bulletin Internal, (Sc. math. et nat.), 1898. 
SAKAMURA, F. Experimentelle Studien über die Zell- und Kernteilung mit 
besonderer Riicksicht auf Form, Grösze und Zahl der Chromosomen, Journal 
of the College of Science, Imperial Univ. of Tokyo, Vol. XXXIX, Art. 11, 
March 20th, 1920. 
SCHAFFNER, J. H., Contribution to the Life-History of Sagittaria variabilis 
Bot. Gaz., 23, 1897. 
SCHNIEWIND—TuiEs, J., Die Reduction der Chromosomenzahl und die ihr 
folgenden Kernteilungen in den Embryosackmutterzellen der Angiospermen, 
Jena, 1901. 
ScHürHorF, P. N., Ueber die Teilung des generativen Kerns vor der 
Keimung des Pollenkorns, Arch. f. Zellf., 15, Heft 2, 1919. 
STRASBURGER, E., Neue Untersuchungen über dem Befruchtungsvorgang der 
Phanerogamen usw., Jena, 1884. 
WieGcanp, K. M., The development of the microsporangium and microspores 
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From the Laboratory for the Physiology of Plants of 
Prof. Ep. VurscHarreLt, Hortus Botanicus. 
Amsterdam, February 1921. 
