184 CLINICAL BACTERIOLOGY AND 



aspect of the bend of the knee, with, of course, due anti- 

 septic precautions. 



Each animal is weighed daily. At the end of the 

 second week one is killed, and a careful post-mortem 

 examination made. If no tubercular lesions are shown, 

 kill another at the end of the third week, and if the results 

 are negative the third should be kept alive for six weeks, 

 and then killed. 



If lesions looking like tuberculosis exist, a careful micro- 

 scopical examination for the acid-fast bacilli should be 

 made, and this, combined with the macroscopical appear- 

 ances, forms conclusive proof. 



Macroscopical Post-Mortem Lesions in Bovines. 



Having made a careful clinical examination of our sub- 

 ject, and suspecting tuberculosis, we subject her to the 

 test (tuberculin), and if she reacts, and more particularly if 

 we have isolated from the materia morbi an acid-fast bacillus, 

 we may with safety certify her to be suffering from tuber- 

 culosis, and need not be apprehensive — if our examination 

 technique is accurate — that our post-mortem investigation 

 will not substantiate our ante-mortem opinion. 



As the term " tuberculosis " implies, this disease is charac- 

 terized by the formation of tubercles or nodules, which 

 tend to undergo cheesy degenerative changes. 



In the early stages these nodules are small, grey, clear 

 growths, but as they become older they take on a yellow 

 appearance, like a piece of cheddar cheese in colour and 

 consistence — caseation. Later these nodules often become 

 gritty in consistence — calcification. 



When the respiratory system is affected, the disease shows 

 itself either as a diffused deposition of a large collection of 

 small foci, on section, in the lung parenchyma — miliary 

 tuberculosis — or large centres of purulent, cheesy, or cal- 

 careous masses may be distributed through the lung - tissues. 

 The mediastinal lymphatic glands in such cases are usually 



