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This book of Child's on the Origin and Development of the Nervous System from a Physiological Viewpoint follows logically from his previous works which have had to do with the discussion of the nature of individuality in organisms and the nature and characteristics of physiological gradients.
In this book the question of the origin of the nervous system is developed from the point of view of the physiological gradient, which is looked on as nothing more than an “ordering, and integrating factor in developmental physiology.” The organism from this point of view is regarded as “representing essentially a behavior pattern, arising in protoplasm in response to its relations with the external world.” Anatomically the nervous system is the record in protoplasm of these behavior patterns and functionally it is the chief organ of integration. Such are in general and broadly speaking the theses maintained in this most fascinating little book. In it the reader will find an abundance of facts from the physiological laboratory relating to the fundamental functions of nervous structures, ably presented and suggestively discussed, such matters as de-differentiation in relation to the quantitative rather than the qualitative characteristics of the stimulus, a careful criticism of the relation of electric potential to nervous discharge, interesting comments upon Parker's theory of the priority of muscle tissues in the course of development, and a careful critical examination of Kapper's neurobiotaxis theory. The argument goes forth from a consideration of cell patterns to axiate patterns, the development of symmetry, neuron patterns, the centralization and the cephalization of the nervous system and the dominance of the head end. The whole argument is based upon energic concepts, the organism and the nervous system being treated from the physiological point of view as manipulators of energy. The laying down of behavior patterns, the domination of the head end, and such concepts reac