Abstract
The writer made a cytological investigation on some plants of Broussonetia Kazinoki Sieb. In plants collected from Ueda, Nagano Prefecture, 13 bivalent chromosomes were clearly counted in I-metaphase of P. M. C. and the meiotic behavior was quite normal. This number was ascertained by the further observation on the mitosis in its root-tip cells, showing 2n=26. While some plants from Nagasaki Prefecture showed 39 chromosomes in root-tip cells, giving the triploid number.
It is noteworthy that the basic number of chromosome in Broussonetia Kazinoki may be 13 and that of the nearly related genus Morus is 14 as well as both of them have triploid plants.
