KROH (1956) has recently reported the following interesting experimental results with the self-incom-patible Raphanus raphanistrum: four different self-pollination methods after removing the stigma pro-duce some fruits respectively. The fertility of cross-pollination after removing the stigma is almost as low as that of self-pollination after removing the stigma. This fact leads to the conclusion that the relatively low fertility of self-pollination after re-moving the stigma is due to the mechanical injury caused by the experimental treatment. The intro-duction of pollen grains into the stigmatic tissues produces an eighty percent of selfed fruits. Conse-quently it seems probable that the inhibiting reaction is limited to the surface stigmatic tissues.
The present author paid attention to these results and attempted experiments similar to these with the self-incompatible Japanese radish. The results ob-tained were fully in accord with those of KROH (See Fig. 1, Table 1, 2, 3 and 4).