350 DISEASES OF THE RESPIRATORY ORGANS. 



In more chronic cases, in which perhaps the bacilli are less 

 virulent or are admitted more slowly to the lungs, the nodules 

 are larger and not so numerous ; the areas of caseous degen- 

 eration are much more extensive. 



FIG. 154. 



Acute miliary tuberculosis of the lungs, a, a 1 , a 2 , a 3 , tubercles with central caseation, 

 in part in parenchyma on alveolar tubes (b, b l ), in part situated on bloodvessels. 

 In many tubercles giant-cells. X 40 (Schmaus). 



Acute Phthisis. 



As has already been pointed out, the main features of 

 phthisis are the lobar and lobular consolidations, which are 

 wont speedily to undergo caseation. The size of these pneu- 

 monic areas may vary greatly. 



In the earlier stages grayish miliary patches, one-twelfth to 

 one-sixth of an inch in diameter, stand out prominently be- 

 neath the pleura or upon the congested cut surface of the 

 lungs, in greatest number at the apices. Microscopically the 

 patches are found to have each a caseous centre, which is 

 structureless and granular in appearance the outline of the 

 air-spaces may, however, be faintly discernible; further away 



