The object of the present paper is to point out that two different working parts of muscle have hitherto been generally confounded together, whereas their analogues in the psychic mechanism have always been deemed separable. Scientific explanations of the phenomena of mind, however, seem ultimately to wait on knowledge of what happens in excitable tissues, such as muscle, so that the result of finding two working parts in the psychic mechanism, where it was believed there was only one analogue muscle, has been the introduction into physiological psychology of a number of what I have to suggest are superfluous terms. In addition, the present paper deals with the possible nature of the connection between cerebral excitation processes and the psychic response.