Haufbauer and Holzknecht1 first noted that the diaphragm of the dependent side in a person lying on one side made a larger excursion and was relatively higher than the half of the diaphragm on the upper side. The probable explanation of this change is that the abdominal viscera drop to the dependent side and push up that half of the diaphragm. In a series of observations published with J. A. Sevier,2 we noted that "in most subjects—but not in all—the diaphragm on the dependent side at first increases its excursion," and also "at the end of from thirty to sixty minutes the increase in the diaphragm excursion subsides and the diaphragm movement of the two sides may be equal or reversed."
For several years I have found that this physiologic variation could be used as a diagnostic test for diaphragmatic pleurisy. It is well known that the