The evidence in the smaller bronchial tubes, both those with cartilage and those without, that an inflammatory reaction of some degree may occupy the muscular coat is of importance. We have found reactions of inflammation in the muscular coat varying from a mild œdema and cellular exudate to an intense polymorphonuclear leucocyte involvement. In the latter the muscle fibers showed evidence of degenerative change and suggested an acute weakening of this layer. We lay particular importance upon this finding as indicating a causative factor in the development of acute bronchiectasis as was met with in one of our cases. In this particular instance the bronchi passing to the lower lobes of each lung were unusually dilated and could be followed, in the gross, to their distant extremities. The dilatation was more or less uniform and no large pouches or cavities had developed. A mucopurulent exudate was found occupying these dilated tubes. Others have likewise observed the development of acute bronchiectasis under these conditions. Goodpasture and Burnett found that as early as the second to the fourth day one of the striking appearances was the gaping dilated condition of the infundibula, and the tendency to dilatation of the air passages was manifested in a bronchiectasis in 4 out of 30 cases. Boggs as well as Lord have reported upon chronic bronchiectasis associated with the B. influenzæ and there appeared to be evidence that a certain percentage of cases recovering from influenza permanently develop irregular dilatations of the bronchial tubes.