When blood is effused in any large quantity into the pleural sac—as indicated by the exsanguine appearance of the patient, increasing dyspnœa, occasional hemoptysis, and the stethoscopic signs on auscultation,—the inference is, that the lung has been opened, and that it is from its structure the blood is flowing. The amount of hemorrhage in wounds of the lungs will greatly vary according to the direction of the track of the ball; for the large vessels cannot here glide away from the action of the projectile, as they may in the neck or extremities of the body. Wounds, therefore, near the root of each lung, where the pulmonary arteries and veins are largest, are attended with the greatest amount of hemorrhage; and as coagula can hardly form sufficiently to suppress the flow of blood, are generally fatal. Hemoptysis indicates injury to the lung, but does not give assurance that this organ has been penetrated. It generally accompanies gunshot wounds of the lung in a greater or less degree, no doubt always when a bronchial tube of large size is penetrated; but, as may be ascertained by careful perusal of recorded cases, is sometimes wholly absent, even though the patient may be troubled by cough. Dr. Fraser, in a recent monograph on Wounds of the Chest, states that out of nine fatal cases observed by him in the Crimea in which the lungs were wounded, only one had hemoptysis; and out of seven in which the lungs were found not to be wounded, two had hemoptysis. This, however, from the writer’s observation, would appear to be an unusual proportion of cases in which hemoptysis was not present after wounds of the lungs. Dyspnœa is a frequent accompaniment of wounds penetrating the lung, but not a constant symptom before inflammatory action has set in. When dyspnœa is great in the early period, it will often be found to depend upon the injuries to the parietes, and to the pain caused on taking a full inspiration; as a sign of subsequent mischief in the progress of the case, it is, of course, very constantly present. It is now known that the opening of the pleura does not necessarily induce collapse of the lung, even though unfettered by adhesions, during life. It was formerly supposed that the escape of air by the wound was a sufficient proof that the lung had been opened by the projectile; but it is evident that it is not so, as the air may enter by the wound and be forced out again by the expansion of the lung in inspiration, or by the action of the chest on expiration. If air and frothy mucus with blood, as noticed in one of the cases recorded in the Crimean campaign, escape by the wound, there can be no doubt of the nature of the injury. Emphysema is not common in penetrating gunshot wounds, but occasionally happens. The free opening generally made by the projectile sufficiently explains this fact.