The Stereotropism of the Dogfish (mustelus Californicus) and Its Reversal through Change of Intensity of the Stimulus

1. The dogfish responds to certain contact stimuli by definite stereotropic reactions. These reactions can be positive or negative. 2. The sense of the stereotropic response depends on the strength of the stimulus; a "weak" stimulus, produces a positive and a "strong" stimulus, a negative response. 3. The strength of stimulus necessary to cause a reversal of the reaction depends in part on the physiological state of the animal. 4. The stereotropic reactions occur equally well in the absence of the forebrain.