An operation of isolation of the carotid sinus with the following introduction of the physiologic saline into the carotid sinus has almost no effect on the titer of antibodies in the blood. Preliminary treatment of receptors of carotid sinus by Novocain and by sodium fluoride does not change its sensitivity to the antigenic stimulation. Introduction of antigen on this background brings about production of antibodies, the titer of which reaches the same level as in antigenic stimulation without preliminary treatment by these substances. Treatment of receptors of the isolated carotid sinus by cocaine, Dicaine and Sovcaline causes disapperance of the excitability of receptors to the antigenic stimulation. Introduction of typhoid vaccine into the carotid sinus which had been treated by cocaine, Dicaine and Sovcaine does not induce antibody production. The latter supports the view of the reflex mechanism of production of these antibodies.