Extensive Chromosome Breakage Occurring Spontaneously in a Certain Individual of Elymus Farctus. (=agropyron Junceum)

PONTANEOUS chromosome breakage has been reported frequently S in the literature.In the majority of those cases when breakage is unusually high, the effect is confined to a certain kind of tissue or a special type of cells, sometimes only to a certain stage of development.The ordinary frequency of spontaneous breaks is, in general, low.The present paper is devoted to a study on spontaneous chromosome breakage in one individual of the grass Elymus farctus ssp.boreo-atlanticus (= Agropyron junceum ssp.boreo-atlanticum; RUNEMARK and HENEEN, 1963).In this special individual, chromosome breakage is unusually frequent in mitotic as well as meiotic cell divisions.Spontaneous chromosome breakage during meiosis was reported in a variety of materials by many workers.Cases were described, e.g., by