phatic channels by filaria. In other cases it is due to inflammations surrounding the lymphatics and leading to weakness of their walls. It is very commonly observed in the subcutaneous lymphatics, and constitutes the endemic elephantiasis of warmer countries. This condition is particularly common in the lower extremities, scrotum, and labia, but may affect other parts. The skin is greatly thickened and the surface often of irregularly lobulated character. On incision into it there is found an abundant exudation from the subcutaneous tissue of serous or of milky liquid. Obstructive dilatation of the intra-abdominal lymphatics is not unusual. Rupture of dilated branches in the genito-urinary tract may lead to chyluria. Congenital lymphangiectasia may take the form of a diffuse condition affecting the lymphatics more or less regularly in certain parts of the body, or it may appear in circumscribed areas, often in situations in which the ordinary lymphatic supply is not abundant. The diffuse form occasionally presents itself in the new-born in the form of edematous or semicystic swellings of the subcutaneous tissue, resembling those of elephantiasis. In the same group of cases belong the instances of congenital enlargement of the tongue (macroglossia) and of the lips (macrocheilia). In some of these instances the development of the condition does not occur until some time after birth, though the process is in reality congenital. Localized lymphatic dilatations constitute the form of new growth known as lymphangioma (see General Pathology). INFECTIOUS DISEASES. Tuberculosis.-The lymphatics play an important part in the dissemination of tuberculosis within the organs, and they may themselves be involved in the disease. This is beautifully illustrated in cases of intestinal tuberculosis with ulceration. In such cases the lymphatic channels in the serous coat may be seen radiating from a point opposite the ulceration toward the mesentery, and small miliary nodules are seen in their course. Syphilis. The lymphatics may be involved in syphilitic processes in their vicinity, but the changes are not characteristic. TUMORS. In addition to the lymphangiomata referred to, the lymphatic vessels are the primary seat of tumors resulting from multiplication of the lining endothelial cells, which are known as endothelio mata. These tumors are especially common in the serous surfaces, but may also be met with in the skin and elsewhere. The lymphatics bear an important relation to the metastasis of malignant tumors, particularly of carcinomata. The carcinoma-cells enter the lymphatics and are carried by the stream to distant parts of the body; sometimes the lymphatics near carcinomata are found densely packed with cancer-cells. PARASITES. The adult of the Filaria sanguinis hominis resides in the lymphatic vessels, and the embryos may be present in large numbers (see General Pathology). THE THORACIC DUCT. Pathologic processes involving the thoracic duct resemble in general character those of the other lymphatic vessels, but the size of the duct and its anatomical relations make the diseases affecting it of somewhat greater significance than the same diseases when occurring in the smaller lymphatics. Thrombosis may occur in association with inflammation of the duct or without such, and there may be a permanent occlusion in consequence. Dilatation of the lower parts of the duct, as well as of the lymphatic vessels of the abdomen, may ensue, and sometimes the receptaculum or other portions of the duct may become cystic. Chylous ascites may likewise result. More commonly collateral circulation re-establishes circulation and serious consequences are not observed. Dilatation of the thoracic duct may also result directly from cardiac failure with engorgement of the greater veins. The outflow of lymph is impeded, and in some cases the backward pressure of the blood through the superior cava may fill and distend the upper part of the thoracic duct with blood. Inflammation occurs in consequence of various inflammatory diseases of the abdomen or of the pelvis, by the invasion of irritants through the lymph received from the affected areas. There may also be direct extension of inflammation in cases of abdominal disease, or in pleurisy or other intrathoracic affections. Tuberculosis affecting the abdominal portion of the duct is sometimes observed in cases of intestinal or mesenteric tuberculosis, and may occasion secondary miliary tuberculosis, particularly the form in which the disease is subacute or chronic in its course (Weigert). Tumors.-Primary tumors are sometimes observed, and seeondary carcinoma is more commonly met with. CHAPTER IV. DISEASES OF THE RESPIRATORY SYSTEM. THE NASAL CAVITIES. Anatomic Considerations.-The mucous membrane of the nose is unusually prominent, especially over the lower turbinated bone, where it is 4 mm. thick. In the lower, or respiratory, parts of the nose the epithelium is stratified ciliated columnar. The submucosa is replete with a venous network, giving it, particularly over the inferior turbinated bone, the appearance of erectile tissue. In the olfactory regions non-ciliated columınar cells, which become attenuated at the inner end, line the surface. Between the filiform prolongations within lie round and tapering olfactory cells. Small tubular and racemose serous and mucous glands are freely distributed in the mucosa. CONGENITAL ABNORMALITIES. Deviations of the septum and other slight anomalies are common. Atresia, absence of the septum or other parts, or complete absence of the nose, are rare defects. Harelip and cleft palate frequently involve the nasal cavities. CIRCULATORY DISTURBANCES. Active congestion occurs in consequence of exposure to great heat or cold, or of ascending elevations; and when the heart is overstimulated. Passive congestion may be due to cardiac weakness, obstructive diseases of the lungs, and local pressure on veins. Hemorrhage.-In either passive or active congestion hemorrhage (epistaxis) may occur. Bleeding may, however, result from blood-diseases (hemophilia, pernicious anemia, leukemia), from disease of the blood-vessels (arteriosclerosis), or in a paroxysmal form from obscure causes. Epistaxis is a frequent prodromal symptom of typhoid fever; less frequently it occurs in influenza and other infections. Edema of the mucous membrane may be associated with inflammation. INFLAMMATIONS. Acute nasal catarrh (acute rhinitis; coryza) commonly results from exposure to cold. Irritant fumes may cause it ; often it seems infectious and contagious. It may occur as an associated condition in various infections, as grip, typhoid fever, measles, etc. The mucosa is at first intensely red and dry; then an irritating serous, followed by mucous and finally mucopurulent, exudation is discharged. Herpes or eczematous eruptions of the lip are common. Considerable inflammatory edema of the mucous membrane of the nose and accessory cavities may occur. Chronic rhinitis follows repeated acute attacks, especially in scrofulous, tuberculous, or syphilitic persons. The mucosa, especially over the inferior turbinated bone, becomes thickened (hypertrophic rhinitis) and may remain so, or undergo atrophy (rhinitis atrophica). In the latter the exudate is scanty and appears as dry, greenish crusts, which sometimes occasion extensive ulcerations and become horribly offensive. To such cases the term ozena is applied. Various forms of bacilli and micrococci have been discovered, the most frequent being an organism resembling the bacillus of Friedländer. Fetid discharges may also occur in syphilitic or tuberculous diseases of the nose (ozona syphilitica s. tuberculosa). INFECTIOUS DISEASES. Diphtheritic rhinitis is usually secondary to pharyngeal diphtheria. Primary diphtheritic rhinitis of rather benign character is occasionally observed. Non-specific diphtheritic rhinitis is a very rare condition. Syphilis in the secondary stage and in congenital cases sometimes occasions simple catarrhal rhinitis. Mucous patches may occur, or gummata springing from the mucous membrane or from the periosteum or perichondrium. The latter tend to ulcerate and cause destruction. The purulent discharge may be fetid. Tuberculosis may occur as disseminated or aggregated tubercles of the mucous membrane, or as ulcers and carious processes. These are all rare, but "scrofulous catarrhs" of children, probably often tuberculous, are common. Lupus of the face may extend to the nose. Glanders occasions intense purulent and hemorrhagic rhinitis, or nodular growths with ulceration. Nodules and ulcers in lepra, and irregular swelling and induration of the mucous membrane of the nose and the adjoining skin in rhinoscleroma are rare conditions. TUMORS. The commonest form of tumors is the polyp, which is sometimes distinctly the result of hypertrophic rhinitis, at other times obscure in origin. Polyps present the ordinary structure of the nasal mucosa, with a tendency to cystic change from occlusion of the glands, or to adenomatous appearances from proliferation of the glandular elements. Fibroid, myxomatous, and sarcomatous polyps also occur. In all cases there is a tendency to recurrence after removal. A rare form of hairy polyp has been recently described. Chondromata, osteomata, sarcomata, and epithelial or glandular cancers may be found. PARASITES AND FOREIGN BODIES. Larvæ of various flies may occur in the nasal chambers and set up serious inflammatory lesions. Foreign bodies may become incrusted with lime-salts and lead to the formation of rhinoliths, THE LARYNX. Anatomic Considerations.-The lining epithelium of the larynx is stratified squamous as far as the false vocal cords. Below these and throughout the ventricles it is stratified ciliated columnar, and thus continues into the trachea and bronchi, excepting over the true vocal cords, which are covered with stratified squamous epithelium. The tunica propria contains much yellow elastic fiber, and the submucosa is quite loose, especially over the base of the epiglottis and the aryepiglottic folds. CONGENITAL ABNORMALITIES. Minor defects in shape of the constituent parts of the larynx are not rare. Congenital fistulæ communicating with the exterior, and dilatation of the ventricles similar to the normal pouching found in certain monkeys, are occasionally met with. Abnormal largeness and smallness, the latter especially in persons having poorly developed sexual organs and those castrated early in life, are more frequent conditions. CIRCULATORY DISTURBANCES. Anemia may occur in general anemia, and is sometimes found in tuberculous and chlorotic subjects in pronounced degrees. Active hyperemia follows exposure, overuse of the voice, and irritation by gases, dust, and the like. Passive hyperemia occurs in heart-diseases, intrathoracic tumor, and other conditions obstructing the venous circulation. In active congestion the larynx is bright red; in passive congestion it is dark red in color, and distended veins may be prominent. Hemorrhages are seen in the mucosa after death from asphyxia, in cases of purpura or other hemorrhagic conditions, as well as in intense inflammation of the larynx. Large hemorrhages may occur in cases of cancer. Edema of the epiglottis, the aryepiglottic folds, and other parts of the larynx may be part of a general anasarca in Bright's |