The physical signs are those of pleural effusion. The friction râle is not heard, however, and, as fibrinous adhesions do not exist, the fluid is more apt to change its level with the varying position of the patient than is common in fibrino-serous pleurisy. Compression of the lung rarely, if ever, occurs.

The prognosis is that of the primary disease.

The treatment also is that of the primary disease. The dropsies are to be treated by heart-stimulants, diuretics, and cathartics. If the breathing be embarrassed by the transudation, and no relief follows medicinal measures, repeated aspirations are to be resorted to.

HÆMOTHORAX.

Etiology. Hemorrhage into the pleural cavity may occur from rupture of an aneurysm, from erosion of an intrathoracic vessel, or from injuries resulting in fractures of the rib or in laceration of the lung.

Pathology. The blood may coagulate and be absorbed. if not too excessive in amount.

If infection occurs, there

may be pleurisy with effusion or empyema.

The symptoms are those of hemorrhage-pallor, dyspnoea, thready pulse, sighing respirations, and restlessness, associated with pleuritic pain and dyspnoea. Symptoms of pleurisy with effusion or of empyema may develop in infected cases.

The physical signs are those of pleural effusion. The friction râle is, however, absent.

Prognosis. A large hæmothorax, such as arises from rupture of an aneurysm, is rapidly fatal. Small hemorrhages, especially those due to injury, may terminate in absorption and recovery.

The treatment is that of acute anæmia-by transfusion, warmth to the extremities, and small doses of opium. A

small hæmothorax is best left alone. If the clot be infected or be large enough to interfere with respiration, it may be evacuated by incision.

5. DISEASES OF THE MEDIASTINUM.

LYMPHADENITIS.

Simple lymphadenitis follows inflammations of the lungs or the bronchi, especially in children. More rarely the condition arises in the course of some infectious diseases, especially typhoid fever and diphtheria.

The lesion consists of swelling and congestion of the gland, resulting either in resolution or in enlargement. Suppuration rarely occurs. Not infrequently the glands become secondarily infected by the tubercle bacilli.

The adhesion of an enlarged gland to the oesophagus may result in a traction-diverticulum.

The symptoms are rarely observed. In some cases bronchitis with paroxysmal cough results from congestion and irritation of the neighboring structures.

Suppurative lymphadenitis may follow simple or tubercular inflammation of the glands. The pus may finally be inspissated, infiltrated with lime-salts, and encapsulated, or it may rupture into the bronchi or the oesophagus.

Tubercular lymphadenitis regularly accompanies tubercular lesions in the lung. In other cases the glands filtering out the impurities gaining entrance to the lungs may primarily be infected. The tubercular glands may attain a large size and may cause the pressure-symptoms of a mediastinal tumor. The caseous masses may become inspissated and encapsulated, or they may rupture into neighboring organs. The lungs, the pleura, or the pericardium may

be involved secondarily by extension. General tuberculous infection so commonly results, especially in children, that search should be made for tubercular glands of the mediastinum in every case of acute miliary tuberculosis of obscure origin.

MEDIASTINAL TUMORS.

Of 520 cases of mediastinal tumor reported by Hare, cancer occurred in 134, sarcoma in 98, and lymphoma in 21. Less frequently are found dermoid and hydatid cysts, fibroma, lipoma, gumma, and enchondroma. Growths formed by the aggregation of tubercular glands and aneurysms have previously been described. Cancer may be primary or secondary. Sarcoma is more apt than cancer to be primary, men are more frequently affected than women, and the majority of cases occur between the twenty-fifth and fortieth years.

The symptoms are due to increasing intrathoracic pressure. Dyspnoea is the most marked symptom; it is due to pressure on the trachea, the recurrent laryngeal nerve, the lungs, or the bronchi. In the latter stages of the disease orthopnoea is usually developed. Cough may be paroxysmal, resembling that of whooping-cough, or there may be a brassy cough as with aneurysm. Pressure on the thoracic duct occasions rapid emaciation. Dysphagia occurs if the œsophagus be compressed. Compression of the thoracic veins results in cyanosis of the chest, the arms, the head, and the neck, and in extraordinary attempts to establish collateral circulation. Congestion and oedema of the lung may be occasioned by pressure on the pulmonary vein. Pleural effusion is apt to appear either by an involvement of the pleura by the new growth or from pressure of the tumor on the vena azygos or on one of the intercostal veins. Pain is not as common with tumor as with aneurysm.

Physical Signs.-There is evident dyspnoea. Some valuable aid in localizing mediastinal new growths is afforded by noticing what position of the patient best relieves the pressure-symptoms and modifies the dyspnoea. There may be blueness of the upper part of the body and arms, while the enlarged thoracic and anastomosing abdominal veins stand forth prominent and distended. According to Osler, the distention and enlargement of the thoracic veins are more marked with lymphadenoma than with cancer or with sarcoma. The sternum or the intercostal spaces on either side may be bulged forward or may be involved by the growth. A transmitted expansion frequently suggests aneurysm, but it is not so marked, there is no lateral expansion, and there is no diastolic shock. The tracheal tug is seldom if ever obtained, and over the tumor no murmur is detected, as in the latter disease. Dulness is elicited by percussion over the growth, either over the upper sternum or between the spinal column and the scapula in case of involvement of the posterior mediastinum. The breathing on either side may be feeble from bronchial compression or may assume a tubular character. The physical signs are modified by the signs of pleural effusion or of cancer of the lung or the pericardium.

Diagnosis. Many points of differential diagnosis from aneurysm of the aorta have already been alluded to. In many cases a positive diagnosis cannot be given, although, should the patient live over eighteen months, a malignant mediastinal growth may probably be excluded.

The prognosis depends upon the nature of the growth. Treatment. In cases of lymphoma the administration of arsenic is often followed by a diminution of the growth. For radical cure surgical treatment alone can avail, but as this is rarely possible, the medicinal treatment is merely palliative, to quiet the pain and to relieve the dyspnoea.

Opium may be given without conscientious dread of forming a habit.

ABSCESS OF THE MEDIASTINUM.

This affection is usually of traumatic origin; it may, however, be secondary to infectious fevers, to pyæmia, to erysipelas, or to suppurative disease of the adjacent viscera. Chronic abscesses are usually of tubercular origin. The abscess, which is usually situated in the anterior mediastinum, is more common in males than in females. The pus

may finally become inspissated and encapsulated, or it may rupture through the sternum, through an intercostal space, or into the oesophagus or the trachea, or it may burrow into the abdominal cavity.

The symptoms are those of abscess and pressure. Pain is marked from the start, is of a throbbing character, and is associated with exquisite tenderness. Irregular fever, chills, and sweating mark the presence of pus. Cough, dysphagia, and dyspnoea occur as pressure-symptoms.

The prognosis must be guarded, owing to the possible complications.

Treatment. In the earlier stages the ice-bag or the cold Leiter coil should be employed continuously. When pus has formed it may be evacuated by trephining the sternum.

EMPHYSEMA OF THE MEDIASTINUM.

This condition is met with in trauma, follows the operation of tracheotomy, and may result from rupture of the peripheral air-vesicles of the lung during violent coughing or straining. Air may enter the cellular tissue of the mediastinum by perforation of ulcers of the trachea, the bronchi, or the oesophagus. The emphysema may be limited to the mediastinum, may rupture into the pleura,