THE PROPER THERAPY for chronic pulmonary emphysema is dependent on a clear understanding of the pathological picture of the disease and the mechanisms by which it produces the symptoms. Microscopic examination reveals that the alveoli, so essential for diffusion of gases between the inspired air and the pulmonary capillary blood, are destroyed and replaced by large air-containing spaces which function less effectively in the exchange of gases. The characteristic symptoms of pulmonary emphysema are chronic cough, dyspnea, and wheezing. Physiological studies reveal evidence of obstruction to expiratory air flow. The diagnosis of destructive pulmonary emphysema during the patient's life is somewhat difficult because the clinical picture may be identical to that of allergic bronchial asthma or chronic bronchitis. Physical findings, roentgenographic examination, and a study of pulmonary function may not aid in differentiating among these entities, though a careful clinical history usually permits the identification of allergic bronchial asthma