The phenomena of memory are nothing but those of the phenomena of association by contiguity, in which the suggested idea brings with it so much of its environment as to be referred to the past. Hence, whatever cerebral explanation is given for association in general must be applied to the chief constituent of memory. Dr. Edridge-Green (p. 145) appears to locate association by contiguity in the optic thalamus. Considering that association by contiguity is nothing but mental habit, and that habit-taking is one of the fundamental attributes of protoplasm in general, the theory of this work could not well be narrower or more arbitrary.
