in the tracing is due, according to him, to contraction of the antagonistic muscles. The tendency of most of these results is to lead, according to Dr. Waller, to the view that the centres, getting fatigued first, cannot voluntarily overdrive their executive servants, — the end-plates and muscles.
Next Dr. W. reviews "with great reluctance " the experiments by which Bernhardt, Ferrier, and Brunton have compared our estimation of weights by voluntary and by faradic lifting. These have been quoted to prove that peripheral 'muscular' sensations are quite enough to account for what delicacy of discrimination we possess when 'hefting' weights. W. finds an enormous inferiority in the faradic method, — an inferiority even to the passive discrimination of weights by the skin of the supported hand, and such as can only be explained by a positively inhibitory effect, upon our 'muscular' sensations, of the faradic current used. W. also considers the anatomical proofs for the existence of sensory nerves in muscle-tissue to be inadequate.
He finally passes to the psychological question about effort. Testimony to the effect that effort can be introspectively analyzed into peripheral feelings he rejects as no better than testimony that we introspectively discern something non-peripheral. He does not, of course, deny the presence of afferent factors in effort and fatigue; but that they can be the only factors needed for the regulation of our outgoing exertions he considers disproved by the extreme rapidity with which such minute voluntary adjustments as those of the larynx have to be performed. Apparently there must be here some immediate central consciousness of what discharges are taking place. The outgoing currents must be measured out in advance of our feeling of their effects. In consequence of this consideration and of the part which his other experiments show to be played by the motor-centres in objective fatigue-phenomena, he concludes, as he began, that subjective fatigue and sense of effort must both have central seats, and that the feeling of the outgoing current which Bastian and others have denied must still be admitted to exist by psychologists. Müller, in concluding his report, points to the arbitrariness of Dr. W.'s assumption that objective and subjective fatigue must have one and the same seat. Objective fatigue might be largely in the centres, and yet our feelings of muscular fatigue might be due to the accumulation of waste products in the muscles exciting the nerve ends there. He ends with characteristic sharpness by saying that W. has shown by his so-called objective study how not to reach reliable results. Without going as far as this, I must confess that Dr. Waller's fundamental assumption that objective and subjective fatigue and subjective effort must be held to have the same local seat seems to me singularly frail. I must also say that Müller's criticisms of W.'s
