BY C. J. POUND, F.R.M.S. XXVll 



After the fii^t trial all the healthy animals were strictly 

 isolated from the atiected ones. 



Methods of Detecting Tuberculosis. — Comparative patholo- 

 gists are agreed that there are several diseases which may simulate 

 and be mistaken for bovine tuberculosis. Therefore on all occa- 

 sions, when possible, the clinical diagnosis ought to be controlled 

 by bacteriological examination of the suspected products— pus, dis- 

 charge from the nostrils, expectoration, glandular pulp, milk, etc. 

 If Koch's bacillus is found, with all its well-defined and peculiar 

 histo-chemical characters, the existence of tuberculosis may be 

 affirmed. If the search for tubercle bacilli does not give positive 

 results, as is often the case in cattle, experimental diagnosis is 

 proceeded with. This is done by injecting some of the suspected 

 products directly into the peritoneal cavity of one or more guinea 

 pigs, which are extremely susceptible to tuberculosis. Should 

 the inoculated material be tujberculous, its virulence will be proven 

 by the progress of the disease, the first symptoms usually appearing 

 in from 25 to 80 days, when the animal may be killed and 

 examined. On post mortem, the lymphatic glands and spleen 

 will be seen to be considerably enlarged and crowded with tuber- 

 cular nodules, while the liver and lungs will be less severely 

 attacked. If these appearances are confirmed by microscopical 

 examination, the diagnosis is thus made complete. 



The two methods just described are of course inapplicable 

 when tuberculosis in the suspected animal is confined to the 

 abdominal organs, to serous membranes, or to glands of cavities ; 

 consequently they are impracticable for general use. But, thanks 

 to the researches of Koch, we have in the agent known as tuber- 

 culin a most perfect test for tuberculosis. Experiments made by 

 thousands in all countries have shown that Koch's tuberculin, 

 injected in small doses under the skin of suspected cattle, sets up 

 in tuberculous animals alone an intense febrile reaction, permit- 

 ting one to assert the existence of lesions so minute that all other 

 methods of diagnosis, bacteriological and clinical, would be 

 powerless to reveal their presence, or even to make one suspect 

 their existence ; in fact, it becomes so near being an infallible 

 test that the errors of diagnosis, based on its constant use are 

 practically nil, 



