In his experiments on the fertility in Petunia violacea, the author has found and remarked (Dot. Mag. Tokyo, 1927), that some individuals were sometimes self-fertile under dry condition though they are, as a rule, self-sterile under a wet envilonment. In this paper the author intends to report some further foundings along that line. 1. The flowers of the plants belong to the same vegetative line cultivated under two different envilonmental conditions, namely a wet and a dry conditions, were intra-self pollinated. The nearly-self-sterile plants gave successful results under the dry condition, while the selffertile ones did not give such a clear results. 2. The pistils of the plants, subjected to either of the two conditions above-mentioned, were pollinated with pollens from the same flower belonging to the same vegetative line. In the nearly-selfsterile ones more successful result was obtained from the individuals cultivated under the dry condition than those subjected to the wet envilonment; but just the opposite of this was the case with the selffertile ones. 3. The germinating percentage of the pollen was tested with two kinds of sugar solutions, one containing the stigma-secretion from the individual cultivated under the dry condition, and the other that from the one kept under the wet. In the self-sterile or nearly-self-sterile individuals the pollen germinated more easily on the former than on the former than on the latter, but in the self-fertile ones the r sult was just the opposite. 4. The plant-length, the leaf-area, the water content of the leaves etc. of each individual cultivated under either condition were measured. Nearly all plants became vigorous, containing a large amount of water under the wet condition. Only the self-fertile one was, however, the exception. 5. How the soil moisture effects the fertility is a question may not be easily solved, but the results of the experiment above mentioned, leads to a statement that when the nearly-self-sterile individuals are cultivated under the wet condition, the character of the stigma-secretion becomes unfavourable for the germination and fertility of their own pollen, as the growth of the plant body becomes vigorous. 6. The reason why the self-fertile individual gave the opposite results will be explaine in a future paper.