may sometimes give rise to the conditions. Carcinoma in which ulceration exists may give rise to marked suppuration of the lung.

The abscesses vary greatly as to size and distribution.

The Friedländer bacillus, diplococcus of pneumonia, staphylococcus, bacillus of influenza, and streptococcus are the most common micro-organisms that have been found in the pus. Symptoms. These are not characteristic. The history must be taken into account. Fever of the septic type is present. The physical signs of a cavity are usually noted. Often there is expectoration of pus, which is foul-smelling, and under the microscope contains elastic fibers. Leukocytosis is present in nearly all such cases. If the condition affect the pleura, the signs of pleuritis will be observed.

Prognosis. Is always guarded. In simple abscesses it may be favorable; in embolic abscesses it is always grave. Treatment. The treatment should be supportive. If the abscess is accessible, surgical interference is necessary.

PNEUMONOKONIOSIS.

Definition. A disease of the lungs due to the inhalation of particles of dust, often followed by fibroid changes.

Etiology.-Occupations which expose the individual to the inhalation of dust particles, such as coal-mining, stone-cutting, knife-grinding, and the work of millers predispose to the dis

ease.

Pathology. In the inhalation of dust particles, irritation is first set up in the epithelial lining of the bronchi, producing a catarrhal inflammation which is usually chronic. Later the dust particles are deposited in the lymphatic spaces of the lung, a proliferation of the connective-tissue cells results, and finally fibrous tissue forms, giving rise to interstitial pneumonia.

In this new-formed tissue the particles are held. In the case of coal dust, the lung is black; if due to chalk or limestone it is of a light-gray color.

The lung usually shows diffuse involvement, but the infiltration may be more localized in some instances. The bronchial lymphatic glands almost invariably show infiltration. The lungs are usually increased in weight, especially so in anthracosis. Crepitation is commonly present throughout. In some

instances marked interstitial changes are present, the alveolar and bronchial tissues being replaced by the new formation.

Infection may occur under these conditions by various micro-organisms, particularly by the tubercle bacillus. Abscess sometimes results. The pleura are usually thickened. Emphysema may follow, and bronchitis is generally present.

Varieties. (1) Anthracosis.-This condition is due to the inhalation of particles of coal, and is sometimes called “miners' phthisis." (2) Siderosis.-This condition is due to the inhalation of particles of metal, especially fine steel. It is present in knife-grinders or in those exposed to the inhalation of small fragments of steel and of iron. It has been called "knifegrinders' phthisis," and the average duration of life in persons affected with this form of pneumonokoniosis is about six years. (3) Chalicosis.-This is due to the inhalation of small mineral particles, and occurs in occupations involving the chipping of minerals, such as millstones, etc. (4) Millers' Phthisis.This is found in occupations in which cereals are ground.

Symptoms. The symptoms come on very gradually after many months or even years, first characterized by a more or less well-defined bronchitis. This may be followed by the development of an interstitial pneumonia, or the occurrence of tuberculosis. The sputum often contains the particles inhaled, as well as such characteristics encountered in the sputum of chronic bronchitis.

Diagnosis. The diagnosis depends upon the occupation of the patient, the gradually failing health, the condition of the sputum, and sometimes signs of consolidation, especially at the apex.

Prognosis. The prognosis depends upon the ability of the patient to change his occupation. If the disease be not too far advanced, cure may result.

Treatment.-Prophylaxis consists in means devised to arrest the inhalation of dust particles. The treatment of the disease rests upon general principles.

SYPHILIS OF THE LUNGS.

Definition.-Syphilis of the lungs occurs in two forms: (1) The congenital form; (2) the acquired form. The acquired form is associated with the formation of gummata, and sometimes sclerotic changes.

1. Congenital Syphilis.-This shows itself in the form to which the name pneumonia alba, or white pneumonia, has been given. On section the lung is light-gray, nearly white in color, and almost completely airless.

Microscopically there is wide-spread round-cell and spindlecell infiltration, and fully developed connective tissue in the interalveolar and interlobular substance, with more or less compression of the bronchioles and alveoli. Some of the cells contain numerous fat drops, the structure having undergone fatty degeneration. When pneumonia alba is present, the child is either born dead or dies shortly after birth. The symptoms are indefinite, although consolidation may be revealed upon examination. Evidences of syphilis in other parts of the body will be found. Clinically, white pneumonia can not be differentiated from bronchopneumonia.

2. Acquired Syphilis.

Pathology.-Changes in the lung are due to the formation of gummata, usually accompanied by diffuse interstitial lesions. The gummata are always characteristic, but the condition is extremely rare. They occur in the form of firm nodules, varying in size from a pea to a large apple, with a pale yellow cheesy center of firm consistency, surrounded by a translucent, grayish tissue, ending in an area of injected lung substance. The gummata are likely to appear near the root of the lung, often connected with the bronchi; in this way symptoms of pressure occur. If there are no symptoms of pressure, the condition can not be diagnosticated. Secondary changes which may be of syphilitic origin are interstitial changes, due to the growth of dense connective tissue. The connective tissue may also form in the bronchial wall and peribronchial tissue, producing nodular masses. In this connection bronchopneumonia may result. Sclerotic changes of the blood-vessel walls are also present.

Symptoms. In symptoms referable to the respiratory organs, in the person suffering from acquired syphilis, when other diseased conditions can be eliminated, syphilis of the lung should be suspected. The most common symptom is dyspnea, increased by exertion and becoming worse as the disease progresses. Cough is present, usually with mucopurulent expectoration.

Physical Signs.-The physical signs are those of stenosis of the bronchial tube, or bronchiectasis, or similar signs due

to profound bronchitis or bronchopneumonia. The physical signs, as a rule, are obscure.

Prognosis. The prognosis is unfavorable.

Treatment. The treatment is that of syphilis in generalmercury and iodid of potassium.

NEW GROWTHS OF THE LUNG.

New growths of the lung are rarely primary; they are most often secondary, the evidences of primary growth being found elsewhere in the body, and being transferred by means of the blood or lymphatics.

Primary Tumors. Of the benign connective-tissue tumors, fibromata, lipomata, and chondromata have been observed, but they are rare. Of the epithelial benign tumors, adenomata have been recorded. Of the embryonic connective-tissue tumors, various sarcomata have been found, but are usually secondary.

Carcinomata as primary growths have also been found; these are usually massive growths situated at the base of the lung. They show a tendency to ulceration and degeneration (as is common in carcinoma). They may be of the cylindric variety, or if they spring from the squamous epithelium of the alveoli, are of that type. The neighboring lymphatic glands are involved.

Secondary Tumors.-Secondary tumors are more common in sarcoma than in carcinoma.

Symptoms. The symptoms are those of pressure, the patient complaining of dyspnea, cough, and expectoration; and occasionally hemoptysis occurs. There may be difficulty in swallowing, due to pressure upon the esophagus, or the mass may press upon the recurrent laryngeal nerve, causing paralysis of the vocal cords.

When there is sharp stitch-like pain, the pleura is involved. Physical examination may reveal bulging of the affected side, due to the growth.

Percussion gives flatness, and auscultation shows absence of breath-sounds. Enlargement of the glands in the axilla in case of carcinoma and dilatation of the veins of the neck are of value in diagnosis.

Prognosis. The duration of the disease is from one-half a year to a year and a half in cases of the malignant tumors. Treatment. The treatment is symptomatic.

PARASITES.

The echinococcus or hydatid cyst occasionally appears in the lung. It usually represents the extension from the liver, the cyst having ruptured through the diaphragm. Cough and hemoptysis are sometimes present; however, the signs and symptoms are not characteristic.

DISEASES OF THE PLEURA.

PLEURISY.

Definition.-Pleurisy is an inflammation of the whole or a part of the pleura. The condition may be either acute or chronic.

The disease may be classified into dry or adhesive, and pleurisy with effusion. Pathologically the disease may be classified into fibrinous, serofibrinous, purulent inflammation, and fibrous or chronic pleurisy.

The disease may be primary or secondary. The clinical classification is divided into the acute and the chronic forms.

DRY, FIBRINOUS OR PLASTIC PLEURISY.

Etiology. The condition is often the result of prolonged exposure to cold. It may often occur in the rheumatic diathesis, in many of the infectious diseases, and in rare instances may be due to syphilis. Traumatism is also a prominent cause.

In the majority of instances the disease is secondary, due to some affection of the lung, one of the principal causes being pulmonary tuberculosis; next in frequency, croupous pneumonia and infarcts of the lung. It occasionally occurs in connection with pericarditis.

Pathology. The pleura is usually involved to a limited extent, although the entire area may be affected. The earliest change noted is a reddening of the surface. The pleura loses its luster, becomes rough and dry, and later the fibrinous exudate will be formed upon the surface, which varies greatly as to extent and thickness. The visceral and parietal layers may become temporarily adherent as a result. The earliest change is hyperemia, followed by the migration of leukocytes