In a previous communication by Lewis and myself it was demonstrated among other things that the death of guinea-pigs in immediate anaphylaxis was due to the production of a stenosis in the pulmonary air passages so that air neither left nor entered the lung and we brought forward evidence which pointed to a tetanic contraction of the muscles of the bronchioles due to peripheral action as the immediate cause of this stenosis. This view has since been shared by Anderson and Schultz and by Biedl and Kraus. On the basis of this conception, several series of experiments were carried out to determine, if possible, whether sensitization by the serum affected the vagus endings in the bronchial muscles, the muscles directly, or both structures. The experiments were carried out by sectioning one vagus in the neck, for according to Dixon and Brodie, the vagus of one side supplies the lung of that side only; moreover there is no evidence of a cell station between the pulmonary vagus fibers in the neck and bronchial muscle.