THE BRONCHIAL cartilages extended for approximately 10 generations along axial pathways and were found by Hayward and Reid1 to give support to the proximal half of these generations. Since many of the proximal intrapulmonary bronchi are visible bronchoscopically, it has repeatedly been confirmed by bronchoscopy that the lumen is never obliterated except by severe local processes which damage the wall, such as inflammatory or neoplastic strictures or pressure of diseased lymph nodes. The extent of the bronchial cartilage was found to be normal in cylindrical bronchiectasis, suffered the greatest reduction in saccular bronchiectasis, and was reduced variable degrees in the various intermediate forms of bronchiectasis. Cartilage was scarcely ever found in the walls of bronchiectatic saccules. In bronchiectasis associated with massive collapse, only the bronchi normally supplied with circumferential cartilage remained patent. Because of this it was thought that in massive collapse all the bronchi without circumferential support and