Abstract
1. The action potentials produced by olfactory stimulation were recorded in the olfactory epithelium, nerve and bulb of a toad and a frog.
2. Besides the on-response, the on-off-and off-responses were found in these tissues in response to olfactory stimulation.
3. In the light of histological findings, mechanisms which produce the three types of responses were considered. It was presumed that except an on-element, there exists an off-element in the olfactory epithelium which responds only to the cessation of stimulation.
