Abstract
1. The effects of alum on the early receptor potential (early RP) have been investigated with the isolated frog retina deprived of the pigment epithelium.
2. An application of alum on the receptor side of the retina produced irreversible changes in amplitude, peak latency of the negative phase, andratio of heights of positive and negative phase (shape quotient).
3. Small ozses of alum increased the early RP in amplitude and peak latency, but decreased in shape quotient.
4. Large doses of alum decreased the response in amplitude, peak latency and shape quotient, though all the rhodopsin remains in the outer segment. These findings clearly suggest that the early RP is closely related to the highly ordered structure of the outer segments.
5. The replacement of sodium chloride in the bathing solution with potassium chloride revealed no effect on the shape of the response of the tanned retina.
6. The evidence that changes in amplitude induced by an application of alum are always associated with a constant decrease in the shape quotient suggests that the cornea-negative phase of the response consists of a corneanegative component and a cornea-positive one. This cornea-positive component is probably generated by a conductance change in the membrane of outer segments.
