312 Veterinary Medicine. 



zation. Hence it is especially liable to follow on chronic bron- 

 chitis, chronic pleurisy, hydrothorax and even the irritation 

 caused by foreign bodies which tend to become encysted. In 

 chronic bronchitis, which is so common in solipeds, it extends in 

 a branching form along with the air tubes, involving in different 

 cases bronchiectasis, constriction of bronchia, emphysema, com- 

 pression and obliteration of air sacs and alveoli, collapse of the 

 dependent lung tissue, hence limited to lobules, which become 

 fibroid, compressed and airless. When the' fibroid condition 

 forms around an encysted foreign body it is primarily circum- 

 scribed, but as the offending object is usually located in a bron- 

 chium, the blocking of its lumen is entailed and the condensa- 

 tion and fibroid degeneration of the dependent lobule or lobules 

 follow. When the process starts at the pleura, its extension is 

 mainly at first in the interlobular connective tissue, and the 

 lobules are first compressed, deprived of air and then invaded by 

 the fibroid development. Here the main difference is the com- 

 parative immunity of the peribronchial tissue, the compression 

 and fibrous formation having advanced from the pleura and 

 interlobular tissue instead of from the branching air passages. 

 In cases of sclerosis from miliary glander deposits the fibrous 

 framework of the lung is more universally involved without in- 

 dication of the bronchia or pleura having been primarily or 

 specially invaded. 



Lesions. Beside the general feature of fibrous degeneration, 

 which has contracted on, compressed, and atrophied the enclosed 

 lung tissue, there is a remarkable firmness and cohesion of the 

 tissue, so that it is easily distinguished from simple hepatization. 

 It may be red or gray, and like the hepatized lung is devoid of 

 air, and sinks in water, but it is relatively heavier and sinks 

 faster and deeper. In the earlier stage of red consolidation there 

 is little blood escapes on section, and microscopically the alveoli 

 appear filled with a yellowish exudate. I,ater with the grayish 

 condensation these are usually empty and with their walls in 

 contact. Where the primary lesion has been a broncho-pneu- 

 monia the peribronchial fibroid condensation is especially marked, 

 the bronchia, dilated or constricted, may contain a soft caseous 

 debris or pus collection. Outside the peribronchial thickening, 

 the lung tissue may be represented for some distance by dense 



