Current Comment

INTERSTITIAL EMPHYSEMA  Until recently, little attempt has been made to visualize the pattern which is formed in the pulmonic interstitial tissue by the presence of air. Investigations of the excised fresh lung of the calf after overinflation by air indicated, according to Macklin,¹ that air from the alveoli invades the pulmonic connective tissue and forms a characteristic pattern in the septums and vascular sheaths. When the septums between subdivisions of the lung become filled with air bubbles they stand out prominently both on the external surfaces of the lobes and on the cut surfaces of slices taken through the fixed lobes of all regions. These bubble [ill]led plates block off polyhedral areas of lung substance of variable shape and size. The sheaths of the pulmonary vessels are also distended by large columns of air bubbles, and intercommunications between the air pockets of the septums and vascular sheaths are noted. The pattern of this aberrant air-containing tissue is like that of the human lung with interstitial emphysema. During the time air was being forced into the overdistended calf