By this term is meant inflammation in the smaller bronchial tubes, but not necessarily involving the true bronchioles as they terminate in the air-cells. It may arise from all the causes that are capable of exciting inflammation in the larger and medium-sized tubes. It may occur at any period of life, but is most frequent in infancy and early childhood, and next in persons past the middle period of life. The chief differences in the clinical history of this and ordinary catarrhal bronchitis arise from the greater obstruction to the ingress and egress of air through the inflamed tubes. The same degree of tumefaction of the membrane that occasions but little obstruction in the larger tubes is capable of completely obstructing many of the smaller ones, and thereby causing much dyspnoea and sense of oppression, with frequency of respiration, accompanied at first by an abundance of dry râles in all parts of the chest, followed later by the complete intermixture of dry sounds and moist submucous râles, the latter caused by more or less exudation or secretion of mucus from the inflamed mucous membrane. The addition of the tenacious mucous exudation to the previous tumefaction of the membrane, often so far obstructs the ingress of air to the air-cells of the lungs that the respirations become short, very frequent and noisy, with blueness of the lips, coldness of the extremities, drowsiness, and soon death from suffocation. This result, however, is seldom met with except in quite young children and in persons enfeebled by age or by previous disease.