302 



specific I)if!aiiiinatioiis. 



This inflammatory reaction is not characterized merely by the 

 marked collection of wandering cells in the tuberculous tissue, but 

 also by actual exudation upon the surfaces of the organs. Especially 

 in the pleural cavity of dogs tliis may be seen as a marked sero-cel- 

 lular collection of fluid, the result of a purely tuberculous granula- 

 tion ; and in various tuberculous tissues microscopic examination 

 shows the appearance of thread-like (fibrinoid, Schmauss and Al- 



Fig. 64. 



Miliary tubercle in the liver of a dog (slightly magnified). 



brecht) coagulation masses lying between the proliferating and de- 

 generating cells and suggesting an exudative origin. 



With the proliferation of the tubercle bacilli and their extension 

 into the adjacent tissues the amount of toxic material given of¥ 

 by them and taken up by the lymph becomes increased. The casea- 

 tion is to be ascribed to the influence of this substance ; and in pro- 

 portion to the latter the caseous areas grow' larger as the reactive 

 cell proliferation increases the size of the nodule. At first puncti- 

 form or streaked cloudy specks appear and the necrotic foci fuse 

 into progressively larger and larger, dry, anaemic or (after a fatty 



