1971 年 84 巻 996 号 p. 411-415
In nine clones of Rumex acetosa L., a study was made on morphological variation of certain autosomes which are distinguishable from the others by a smallness of long arm.
They range in arm ratio from 0.15±0.01 to 0.96±0.01 and show no difference in length of long arm, with a few exceptions. The autosome with arm ratio of 0.61± 0.02 or more bears a heterochromatic segment in the distal part of one arm, while the remaining autosomes bear no heterochromatic segment. The decrease in arm ratio among all the autosomes studied is considered to be due to having lost, little by little, the heterochromatic segment, and further to having similarly lost the just inner segment. This segment appears as a hyaline band or a thin scarcely-stained thread at mid-prophase and seems to be slightly different in character from an euchromatic segment.