156 TUBERCULOSIS 
Fig. 31. A PHOTOGRAPH OF A SECTION OF THE ANTERIOR LOBE OF A COW'S LUNG 
ADVANCED IN TUBERCULOSIS. THE ENTIRE LUNG TISSUE IS INVOLVED. THE TUBER- 
CULOUS MASSES ARE SURROUNDED IN SOME INSTANCES BY a QUITE THICK BAND OF 
CONNECTIVE TISSUE. A LARGE PART OF THE TISSUE IS CALCIFIED. THIS ISSHOWN 
BY THE LIGHT OR WHITISH POINTS. (NATURAL sIzE.) 
into the mesenteric lymphatics or the portal vein. It may happen 
that the bacteria may be carried by means of the lymph or blood 
