The author prefaces his discussion of the nervous system by saying, "It would be entirely gratuitous as well as misleading to burden an exposition of mental processes with a mass of detailed physiological data. . . . This has been done too much in the 'physiological psychologies.'" Still, the claims of Physiology are so far recognized that forty pages are given to the consideration of nerve-structure and processes. Postulating that all mental processes are correlated with physical changes, that there is a uniform psycho-physical connection (p. 2), the author advocates the 'dynamic' theory of nervous action — i.e. "that the nervous system is a living organism instinct with nervous force or neural properties throughout" (p. 20). This is assuredly the philosophical theory, but the evidence on which it rests, in so far as it is drawn from the phenomena of contrast, is not without flaw. The terms 'neurility' and 'sentience' are adopted to designate respectively the functions of conduction and registration; sentience includes integration, retention and selection. Under the head of 'selection' we think it would 'puzzle' the undergraduate to explain what is meant by 'memory' in the case of the brainless carp (p. 27). Inhibition is considered "possible in proportion as the system grows away from a single line of action and reaction toward a complex interplay of force-pressures" (p. 37). Still, it is well to call to mind that the comparative lack of reflex action in the spinal cord of man is attributed not to cerebral inhibition, but to want of reflex mechanism in the cord (Foster's Phys. III5, p. 918). In the laws of habit and accommodation and their results as transmitted by generation according to the laws of inheritance, are found the general conception of nervous function (p. 49).
Consciousness is divided into passive, reactive, and voluntary, and it seems to us that the recognition given to 'passive consciousness,' i.e. the purely affective state of mind, must influence future theories of sense-attention. In combating Maudsley's theory of the organic unity of consciousness, the author has taken full space, and given an acute analysis that makes us regret the more the compression of other parts of his work. "Sensibility is the primary and most general form of consciousness" (p. 84) and "sensation is a form of sensibility." Perhaps it is impossible in this connection to avoid the consideration of the relativity of sense-qualities and of contrast. But there is hardly any psychological doctrine which is to be more cautiously treated than that of relativity. Stumpf has called attention to the fact that there are no less than five different laws of relativity (Ton-Psychologie, I, p. 10). Moreover, many of the so-called phenomena of contrast, notably in sound, yet lack experimental confirmation.
After sensation and knowledge and the several classes of feelings comes the discussion of pleasure and pain. Here the definitions of the
