Genetical and Cytological Studies in Allium I. Spontaneous and Induced Variations of Chromosome Number in the Pollen Grains of Tetraploid Allium Odorum L

Since L. Guignari's investigation (1884) various investigators have reported the studies on plants in the genus Allium of Liliaceae, as some species in this genus are cultivated and are noteworthy from the cytological point of view. According to T. Suto's papers (1936, 1936) on the phylogenetic discussion of Liliaceae and Amaryllidaceae, which show the fact that the idiogram type of the chromosomes in Allium is LN (Lilium-Narcissus) type, there are eighty species, seven varieties, nineteen teratological species and other two species in Allium already studied from the view-point of chromosome number. 58 species and one variety have been investigated by Levan in Sweden. It is apparent that chromo somebasic number of Allium plants is x=8, although there are some exceptions which show n=7, 9, and 12. Despite all the facilities for cytological treatments in the liliaceous plants, the genetical studies based on the external characteristics have not advanced very much, because of the general degeneration of sexual reproduction in them. For several years, the writer has been engaged in the genetic-analysis as well as the cytological observations of Allium plants. In this paper the writer gives a detailed description on the distribution of chro mosomenumbers mainly in pollen grains of a tetraploid species, A. odorum, which is cultivated commonly in Japan.