538 BOARD OF AGRICULTURE. [Pub. Doc. 



In the Year Book of the United States Department of Agri- 

 culture for 1894, on page 324, occurs the following : — 



The disease in the early stages can be detected only with the aid 

 of tuberculin. In the advanced stages most careful observers will 

 probably recognize it, or at least suspect it, without the use of tuber- 

 culin. Tuberculin, therefore, has become indispensable in giving the 

 owner an idea of the inroads the disease is making in his herd, and 

 in distinguishing the infected from the non-infected. Tuberculin 

 reveals to us all stages, from the earliest, most insignificant changes, 

 when the animal is outwardly entirely well, to the gravest and most 

 dangerous types of the disease. Tuberculin does not, as a rule, 

 discriminate between these cases. Hence those who use it as a guide 

 must not be disappointed when, after having killed the suspected 

 ones, they find that many are in the earlier stages of the malady. 

 Tuberculin, moreover, is not infallible. A small percentage of cases 

 of disease is not revealed by it. On the other hand, a sound ani- 

 mal now and then gives the reaction for tuberculosis. These lapses 

 must be borne in mind in using tuberculin. In spite of them, how- 

 ever, tuberculin must be considered as of great value in revealing 

 tuberculosis not recognizable by any other means during life. 



In the report on tuberculosis in cattle, presented to the 

 city council of Minneapolis, Minn., H. N. Avery, A.M., 

 M.D., commissioner of health, states as follows : — 



During the past few years the investigation of the prevalence of 

 tuberculosis among dairy herds has been extensively carried on both 

 in foreign countries and in the United States. In this country the 

 work has been in charge of the Bureau of Animal Industry, the cat- 

 tle commissions, boards of health and experiment stations of the 

 several States. The results of such investigations have demonstrated 

 the prevalence of the disease to an extent which is positively alarm- 

 ing in many herds, and its existence in a greater or less degree in a 

 large proportion of the herds which have been examined. The diag- 

 nosis of this disease by ordinary methods being in many cases im- 

 possible, a more trustworthy method has been sought and found. In 

 1880, Koch, who discovered the bacillus or germ of the disease, 

 described the preparation and uses of a fluid which he had prepared, 

 and which has since come to be known as Koch's lymph or tubercu- 

 lin. Tuberculin consists of the concentrated, sterilized liquids in 

 which the bacillus tuberculosis has been grown. It contains no liv- 

 ing bacilli, but it does contain the chief poisons which are produced 



