The Lung's Quiet Zone

Two articles in this issue call attention to the functional importance of disease in smaller airways: Gas Exchange Abnormalities in Mild Bronchitis and Asymptomatic Asthma, by Levine, Housley, MacLeod and Macklem, and Age as a Factor in the Distribution of Lower-Airway Conductance and in the Pathologic Anatomy of Obstructive Lung Disease, by Hogg, Williams, Richardson, Macklem and Thurlbeck. These papers come from the same institution and stem from an idea that originated there a year or so ago. To express the idea, we need to have in mind some rudiments of tracheobronchial anatomy. The modern source book for this is . . .