CRITICAL REVIEW critical iReview. THEORETICAL DEDUCTIONS FROM THE PHYSIOLOGY OF THE CEREBRAL CORTEX. BY

a second volume2 has also been published. The far-reaching importance of this original contribution to the physiology of cerebral function cannot be overestimated. Nevertheless, the difficulties inherent in the method and the time and patience required for its performance have resulted in the limitation of first-hand experience to comparatively few workers, with corresponding lack of discussion of the hypotheses which have been put forward to correlate the results of the work. Already writers on cerebral function have attempted to apply the hypotheses of Pavlov to the elucidation of their problems. Therefore it may not be out of place now to review some of these hypotheses. The space of time elapsed since their! appearance precludes any such comment from being prejudicial to the reception of Pavlov's work in this country. In common with many other well-studied nervous phenomena the 2onditioned reflexes are still obscure in their essential nature; the following discussion of them indicates a fresh point of view of cortical function. THE MEANING OF ' REFLEX.' The word ' reflex ' has long had a specialized meaning, denoting automatic fixed inborn responses of the decerebrate nervous system to stimulation of sensory channels. Although, indeed, used by some to describe certain reactions obtained from the intact animal, the word reflex has come to imply assumed identity with the unwilled automatic response obtainable from subcortical nervous structure. In that reflex salivation can be obtained from a decerebrate animal by contact of food with the lining of the mouth, salivation may be reflex. The association of such salivation in response to a stimulus which requires the function of the cerebral cortex for its effect does not necessarily mean that it is then also reflex. Indeed, it is possibly in nature very different fromn true reflex salivation, The very inflexibility o