Further studies on the chimeras appearing in the storage roots, stems and leaves of sweet potatoes were made, and some new data are given in the present paper. Agronomic variety OKINAWA-No.l00. In the ordinary strain of OKINAWA-No.l00, the surface colour of storage roots is light red. From this strain, one storage root that was light yellow on its entire surface appeared by somatic mutation. The storage roots of the next generation propagated by stem cutting from this mutant were not always light yellow, and there appeared often the individuals having storage roots that were light red, light yellow or striped or flecked with both colours, though it seems to be accepted usually that mutant colour may be kept in the next generation thus propagated. In view of the fact observed the following passibilities may be cited regarding the causes of this phenomenon. (1) In the light yellow or light red storage roots, the genes in regard to the colour were unstable in the cells of meristems forming the periblem of atems, so that the next generation of such storage roots is not fixed to their colour. (2) Even if the surface of storage roots is light yellow or red, the genes in the cells of meristems forming the periblem of stems may be different from those of the surface of storage roots, the cells of different kind being distributed as Chimeras in the tissues. So that the stems derived from a single storage root of an uniform colour may form storage roots of different surface colour, according to the genes in the tissues from which the stems were originated. Agronomic variety Gokoku. In a large cultivation of GOKOKU, a chlorophyll deficient mutant was found. This plant had four nodes, and the shoot from the undermost one was provided with normal leaves and stems, while those from the other three had chimeral leaves and stems in white and green or in red and green. Observing this chimeral plant morphologically and historogically, the sectorial, the periclinal and the mericlinal conditions in chimeral consitution were found. In the cultivation of OKlNAWA-No.1OO and GOKOKU and other strains of sweet potatoes, various mutants in the colour and other characters occur quite frequently, so that it is quite necessary to pay precise attention in selecting seed storage roots in order to avoid the deterioration of the strains.
