TUBERCULOSIS— CONSUMPTION 395 



ent. While the lung tissue between the tubercles is often 

 normal, sometimes the intervening alveoli are filled with 

 tubercular exudate and the interstitial tissue thickened. . By 

 the confluence of smaller nodes great tubercular masses form. 

 Sometimes the center of the mass is hollow (caverns), but more 

 often filled with friable, dry caseation or moist pus. Between 

 some of the cavities and bronchi a communication forms, 

 through which a secondary infection with pus cocci or 

 saprophytic bacteria takes place, in some instances changing 

 the character of the caseous or puriform mass to that of, 

 ichor, causing the color to become grayish and giving it a 

 fetid odor. Tuberculosis of the superficial parts of the lung 

 often extends to the pleura, leading usually to circumscribed 

 pleuritic adhesions. Very rarely a diffuse serofibrinous 

 pleuritis develops. 



In calves pulmonary tuberculosis assumes the form of a 

 catarrhal pneumonia. On cut surface the hepatized area of 

 the lung is strewn with small, round, reddish-gray to yellow 

 areas, which, by confluence, are enlarged to caseous centers 

 the size of a hickory-nut or larger. Bronchitis almost always 

 attends pulmonary tuberculosis, therefore lesions in the 

 bronchi are noted on postmortem. The signs of bronchial 

 catarrh with bronchiectasis are common findings, the dilated 

 air tubes filled with mucus or cheesy masses. At times the 

 bronchial mucous membrane is ulcerous. The trachea is less 

 liable to ulceration than the larynx. In the latter organ 

 tumor-like connective-tissue growths occur, sometimes almost 

 entirely occluding the lumen. On section the neoplasm is 

 found to contain small gray or yellowish tubercles. 



Serous Membrane. — The pleura is most frequently involved. 

 In the earliest stages reddish-gray, small, granules develop 

 surrounded by masses of connective tissue. On section of 

 these masses areas of caseation from a millet seed to a pea in 

 size are revealed. By confluence and simultaneous connec- 

 tive-tissue proliferation, round nodes or cauliflower-like excres- 

 cences protrude from the serous membrane. The protuber- 

 ances may have a broad base or be pediculated. While in 

 consistency they are at first soft, later they become firm to 

 hard. The tubercles are imbedded in the growth of con- 



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