Fluctuations of Attention and After-images. By Edward A. Pace. The Catholic University, Washington, D. 0. Whether, in view of recent investigation, the fluctuations which occur in the perception of sense-stimuli under certain well-known conditions, should be ascribed to the attention, is at best an open question. It is a question, moreover, that may eventually be settled as much by the weight of theoretical considerations as by evidence of an experimental nature. Where so many factors both psychical and physical are involved, and especially where a slight change in any one of these factors is found to parallel the variations in con¬ sciousness, the value of such a factor is apt to be exaggerated. That an explanation should be sought in the organic conditions, peripheral and central, is quite natural; and the task is simplified when, by the exclusion of this or that process, the number of factors can be reduced. But this requirement of method by no means obliges us to assume that the attention itself is not the seat of the fluctuations. Much less can the assumption be justified on the ground that to refer the fluctuations to the attention would land us in the region of the transcendental. For if it be admitted that the attention is an empiri¬ cally given process or state, and that stimuli the perception of which demands a high or even a maximal strain of attention, in some way fluctuate, it is permissible to infer that the attention is the wavering factor. The inference may, or may not be, correct: it may even in¬ volve a well-known fallacy; but it certainly does not imply that the attention is a transcendental somewhat. It is hardly a proof of the transcendental character of anything to maintain that it undergoes