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426 to an "excess discharge" of the energies of the organism, and this excess discharge leading to a selection and retention of such stimulations as are vitally beneficial. Here we see the close relation between the principles of Habit and Accommodation. Though antagonistic in some respects, yet they serve each other, inasmuch as, on the one hand, "the organism accommodates itself, or learns new adjustments, simply by exercising movements which it already has, in a heightened or excessive way," and, on the other, by the very repetition of these new movements through the excess discharge, the foundations of new habitual reactions are laid, and so "accommodation, by the very reaction which accommodates, hands over its gains immediately to the rule of habit."

By the aid of this law of excess, three great stages of adaptation are brought under the formula of organic selection: biological adaptations, conscious imitation, and volition. The first is seen in the responses of plants to certain stimuli, and the reactions of the brainless frog. "The ontogenetic growth of the individual starts with this fundamental adjustment of movements to the stimulations under which the phylogenetic development has so far proceeded." This is "organic imitation." The second shows the application of the law to reflex attention, memory, and thought. The principle of Identity is to be understood from the side of Habit, being the mind's demand that new experiences shall harmonize with the old; the principle of Sufficient Reason is explicable from the side of Accommodation. The third is the highest and final stage, representing, both phylogenetically and ontogenetically, the capability of pictured and purposed actions. This arises through persistent and repeated imitative suggestion, in which the "circular process" (interaction of stimulation and response, as explained above) becomes clearly conscious. Physiologically there is now a central coördinative process, and mentally a comparison of the copy with the child's first effort, followed by further efforts, aiming at a more perfect imitation. Hence the highest volitions and the simplest reactions of the organic life, fall under a common type.

The book has certainly a very praiseworthy aim, viz., to bring all the varied phenomena of growth, physical and mental, under the unity of a single principle. But, worthy as this object is, one lays Professor Baldwin's volume down with a very serious misgiving that, after all, the postulated unity is apparent rather than real, and that his zeal to propitiate the biologists has led him to content himself with a very inadequate account of the facts, e.g., Attention. We