A few years ago we became interested in the occurrence of triangular basal shadows in roentgenograms of the chest of patients suffering from bronchiectasis. The first patient showing a triangular basal shadow discovered by one of us (W. P. W.) afforded an excellent opportunity for the investigation of the production of this type of shadow, as it was possible to study roentgenograms of the chest before and after the injection of iodized poppy seed oil 40 per cent into the bronchi, and later to remove the part of the lung causing the shadow and to observe its gross and microscopic appearance.
The shadows are seen as homogeneous areas of increased density, triangular in shape, with one side of the triangle along the mediastinum, the lower side parallel with the diaphragm and the hypotenuse running from near the root of the lung to join the lower side at varying distances from