THE BRONCHIAL TUBES. 333 



or yellowish psendomembrane. Microscopically this pseudo- 

 membrane is found to consist mainly of the fibrillae of fibrin 

 and migrated leukocytes. 



Chronic laryngitis may follow repeated acute attacks, or re- 

 sult from overuse of the voice ; or it may be secondary to dis- 

 eases of the nasopharynx. The mucous membrane is thick- 

 ened, due mainly to an increase of connective tissue, which is 

 characteristic of all chronic inflammations ; it has quite fre- 

 quently a granular appearance as a result of enlargement of 

 the racemose glands of the larynx, and often there are super- 

 ficial ulcerations or erosions. 



Tuberculosis of the larynx is generally secondary to pulmo- 

 nary tuberculosis, occurring in about 30 per cent, of these 

 cases. The mucous membrane is thickened from the presence 

 of characteristic tubercles or a diffuse infiltration ; to this suc- 

 ceed caseation and ulceration, which may result in destruction 

 of the vocal cords. 



Syphilis also may cause deep infiltrations, necrosis, and 

 ulceration ; secondarily serious deformities may arise from 

 contraction of the newly formed connective tissue. 



Papillomata constitute more than one-half the tumors of the 

 larynx. They are especially common in people whose pro- 

 fession requires the constant use of the voice. They grow 

 most frequently from the squamous epithelium of the vocal 

 cords. 



Epithelioma is the variety of cancer generally met in the 

 larynx. It appears first in the form of a nodular thickening 

 of the mucous membrane, which later undergoes ulceration. 



Sarcoma of the larynx, which is usually of the spindle- 

 celled variety, is not of frequent occurrence. 



The Bronchial Tubes. 



Acute inflammation of the bronchial tubes bronchitis 

 results frequently from the extension of a simple inflamma- 

 tory process in the upper air-passages ; it is also almost a 

 constant manifestation of certain acute infectious diseases, as 

 typhoid fever, measles, scarlet fever, whooping-cough, and in- 

 fluenza. The larger and medium-sized bronchi are involved ; 

 in children, however, the terminal bronchioles and surround- 



