1. The reactions of surviving bronchi have been studied.2. It has been shown that they are constricted by histamine, pilo‐carpine, and by alkali within physiological ranges.3. They are dilated by adrenaline (however constricted), by atropine when the constriction is produced by pilocarpine, and by acid within physiological ranges.4. They exhibit typical anaphylactic reactions to specific sensitising proteins.The expenses of this work were defrayed in part by a grant from the Asthma Research Council. The author wishes to express his thanks to Professor R. J. S. McDowall for advice and criticism.