Abstract
The author is studying the cytogenetical research of Mentha genus, and the results gained in the last year are as follows: 1) somatic chromosome number of commercial species "Hokushin", Mentha arvensis L.var vulgare BENTH, being urged to cultivate in Hokkaido since 1937, is 96. 2) somatic chromosome number of Chinese commercial species, M. arvensis L. Var.Vulgare BENTH is 96. 3) these two are in relation of triploid to old commercial species, "Kitami-akamaru" and "Kitami-shiroge", M. arvesis L. var. vulgare BENTH. And therefore, the creation of triploid will important for the breeding of Japanese peppermint.
