2. _Expiratory Valve-like Obstruction_.--The obstructed side shows marked limitation of expansion. Percussion is of a tympanitic character. The duration of the vibrations may be shortened giving a muffled tympany. Various grades and degrees of tympany may be noted. Breath sounds are markedly diminished or absent. No rales are heard on the invaded side, although rales of all types may be present on the free side. In some cases it is possible to hear a short inspiratory sound. Vocal resonance and fremitus are but little altered. The heart will be found displaced somewhat to the opposite side. These signs are explained by the passage of some air past the foreign body during inspiration with its trapping during expiration, so that there is air under pressure constantly maintained in the obstructed area. This type of obstruction is most frequently observed when the foreign body is of an organic nature such as nut kernels, beans, corn, seed, etc. The localized swelling about the irritating foreign body completes the expiratory obstruction. It may also be present with any foreign body whose size and shape are such as to occlude the lumen of the bronchus during its contracted expiratory phase. It was present in cases of pebbles, cylindrical metallic objects, thick tough balls of secretion etcetera. The valvular action is here produced most often by a change in the size of the valve seat and not by a movement of the foreign body plug. In other cases I have found at bronchoscopy, a regular ball-valve mechanism. Pneumothorax is the only pathologic condition associated with signs similar to those of expiratory, valve-like bronchial obstruction by a foreign body. 3. _Partial bronchial obstruction_ by an object such as a nail allows air to pass to and fro with some degree of retardation, and impairs the drainage of the subjacent lung. Limitation of expansion will be found on the invaded side. The area below the foreign body will give an impaired percussion note. Breath-sounds are diminished in the area of dullness, and vocal resonance and fremitus are impaired. Rales are of great diagnostic import; the passage of air past the foreign body is accompanied by blowing, harsh breathing, and snoring; snapping rales are heard usually with greatest intensity posteriorly over the site of the foreign body (usually about the scapular angle). A knowledge of the topographical lung anatomy, the bronchial tree, and of endoscopic pathology* should enable the examiner of the chest to locate very accurately a bronchial foreign body by physical signs alone, for all the significant signs occur distal to the foreign body lodgment. * Jackson, Chevalier. Pathology of Foreign Bodies in the Air and Food Passages. Mutter Lecture, 1918. Surgery, Gynecology and Obstetrics, March, 1919. Also, by the same author, Mechanism of the Physical Signs of Foreign Bodies in the Lungs. Proceedings of the College of Physicians, Philadelphia, 1922.