126 



BOVINE PATHOLOGY. 



well defined, its stroma is continuous with the areolar 

 tissue of the part in which it is placed. Tubercle cells 

 are generally small, but some few are large, and in the 

 nodule are also present free nuclei in abundance and 



,^%%;i,'Sji 



Fig. 21. — Tubercle. A. Deposit in the air-cells of the lungs, li. Miliary 

 Tubercle, x 200. (After Harley and Brown.) 



granules. The small cells are most frequently seen ; they 

 are rounded, with irregular margins, and each with a large 

 nucleus. ^' They sometimes approach, both in size and 

 appearance, the white cells of blood and lymph. We 

 believe that sometimes a tubercle does develop into a 

 structure like a lymphatic gland (adenoid) '^ (Jones). A 

 tubercle, such as we have just described, is termed 

 '' miliary '' or ^' grey/^ it being semi-transparent and 

 about the size of a millet seed. It is remarkable that it 

 does not increase in size, but new cells which are pro- 

 duced are deposited in its outer vascular zone, and the 

 interior undergoes change. This alteration is degenera- 



