Lt has been proved repeatedly that the activity of a part of the cerebral cortex influences the homologous part of the cortex on the opposite side. Bykov1in 1925 reported that the conditioned salivary reflex to tactile stimuli of a certain point of the skin in the dog may be obtained also from the symmetrical point of the opposite side of the body. In the visual sphere Myers and Sperry,2-5by ingenious experiments in the cat, recently demonstrated that the ability for pattern discrimination acquired by the visual cortex of one hemisphere is also present in the visual cortex of the opposite hemisphere. The experiments of Burešová and Bureš6gave similar results with other methods. Stamm and Sperry7report analogous observations in the somesthetic sphere. Dawson,8,9stimulating sensory nerves, registered cortical evoked potentials both in the homologous and in the opposite senory region of the