It was found that the on-, the on-off-and the off-responses are easily pro-duced by the application of ether vapour in the olfactory epithelium and bulb of the frog and the toad. 1. There was found a tendency that ether produces an on-response at the low concentration, an on-off-response at the moderate concentration and an off-response at the high concentration. The similar transition of the response types was observed, when the velocity of ether vapour was increased. 2. It was found that the types of responses are different at different sites on the olfactory epithelium. 3. The three types of responses were also produced by the application of other anaesthetics, such as chloroform, chlorethyl and organic solvents, such as aceton, petroleum ether, carbon tetrachloride, toluol, and benzine. 4. The on-or the off-slow potential produced by the application of amyl acetate or ether was inhibited by subsequent application of ether. The similar inhibition was also observed by the application of the above odorants. On the contrary, the slow potential produced by the application of other general odours summed on the preceding on-or off-slow potential. It was therefore supposed that such in-hibition occurs due to the anaesthetic actions of ether and other substances stated above. 5. It was observed that the on-induced wave appears even when the corresponding on-slow potential is inhibited by ether and other substances and that the off-induced wave appears before the occurrence of the off-slow potential. It was supposed that these discrepancies between the slow potential and the induced wave originate from the competition between the stimulative and the anaesthetic actions which ether and other substances possess. 6. The mechanism in the olfactory epithelium which produces the off-slow potential was considered.