From:
George Howard Darwin
To:
Charles Robert Darwin
Date:
10 Oct 1878
Source of text:
DAR 210.2: 70
Summary:
Recounts the experiments on Fechner’s law he has found in Helmholz; they are on the smallest perceptible differences of illumination. Describes how to test whether plants’ responses to lights are in accordance with it.
Contributor:
Darwin Correspondence Project
