Hirschmann has shown that after a moderate dose of nicotin stimulation of the sympathetic nerve in the neck causes no dilation of the pupil. He concludes that nicotin paralyses the endings of the dilator fibres in the pupil. In the course of some observations on the physiological action of nicotin, we had occasion to repeat Hirschmann’s experiment; we found in the rabbit that 30 to 40 mgrms. of nicotin injected into a vein stopped the effect of stimulating the sym pathetic in the neck, not only on the pupil, but also on the vessels of the ear.