Changes in the caliber of the bronchi in response to vagus stimulation have been observed by many. As long ago as 1842, Langet1 directly observed constriction of the bronchi of the horse when the peripheral end of a cut vagus nerve was stimulated. Dixon and Brodie,2 in 1903 and 1904, studied the effects of nerve stimulation by recording changes in intratracheal pressure and changes in the volume of a lobe of the lung which had been placed in an oncometer. The method was modified somewhat and used by Weber3 in 1914, and by Braeucker4 in 1925 and 1927, in making further studies. The results of the investigations of these and many others have been overwhelming proof that the caliber of the bronchi may be changed by impulses traveling through the vagus nerve. An admirable review of the entire subject has been presented by Macklin in a