Habit Formation in the Crawfish, Camburus affinis: Robert M. Yerkes and Gurry E. Huggins ............................. 565 The Instincts, Habits and Reactions of the Frog: Robert Mearns Yerkes .............................................. 579 STUDIES IN PSYCHOLOGICAL THEORY. The Position of Psychology in the System of Knowledge: Hugo Münsterberg ........................................... 641 PLATES. OPPOSITE PAGE Plate I ....................................................... 20 " II ....................................................... 24 " III ....................................................... 28 " IV ....................................................... 34 " V ....................................................... 190 " VI ....................................................... 198 " VII ....................................................... 200 " VIII ....................................................... 314 " IX ....................................................... 417 " X ....................................................... 436 Charts of the Sciences, at end of volume. * * * * * STUDIES IN PERCEPTION. * * * * * EYE-MOVEMENT AND CENTRAL ANÆSTHESIA. BY EDWIN B. HOLT. I. THE PROBLEM OF ANÆSTHESIA DURING EYE-MOVEMENT. A first suggestion of the possible presence of anæsthesia during eye-movement is given by a very simple observation. All near objects seen from a fairly rapidly moving car appear fused. No further suggestion of their various contour is distinguishable than blurred streaks of color arranged parallel, in a hazy stream which flows rapidly past toward the rear of the train. Whereas if the eye is kept constantly moving from object to object scarcely a suggestion of this blurred appearance can be detected. The phenomenon is striking, since, if the eye moves in the same direction as the train, it is certain that the images on the retina succeed one another even more rapidly than when the eye is at rest. A supposition which occurs to one at once as a possible explanation is that perchance during eye-movement the retinal stimulations do not affect consciousness.