84 AGRICULTURE OF MAIXE. 



It is a very good plan for a man who is depending for his income 

 upon dairy animals to know as much as he can about the inside 

 of them anyway, and to improve every opportunity to see the 

 anatomy of the cow after she is dead, and particularly, it is well 

 for him in this connection to see the cattle that are killed from 

 the herd. He may from that get some idea of what the condition 

 of his herd is. Up to 15 years ago we would have to stop right 

 here in what we had to say about the detection of tuberculosis 

 in cattle. These were the only methods we had, and it was 

 impossible to detect tuberculosis in a large number of cattle 

 that were but slightly diseased, at that time. In 1890 Prof. 

 Koch, who discovered the germ at first, had perfected a method 

 of detecting tuberculosis in its incipient stages. He had manu- 

 factured tuberculin and had used it, so that it was recommended 

 as a means of diagnosing tuberculosis in living animals. In 

 1890, 1891 and 1892, tuberculin was used by a great many men 

 to determine the presence of tuberculosis. Now what is this 

 tuberculin? In brief, it is beef tea and the products of the 

 growth of the tubercle bacillus. It is made something like this : 

 The tubercle bacillus does not grow very well in nature, except 

 in living animals. It is what we call a parasitic, pathogenic, 

 organism. It will grow in living animals but it will not grow in 

 nature anywhere else. Now by special care in the preparation 

 of a culture, it was discovered that this organism could be made 

 to grow in a laboratory. Beef tea was made, a little glycerine 

 added to it, the living germs put in, and the beef tea containing 

 the living germs put into a warm chamber and kept at about 

 the temperature of the animal body ; and slowly the germs would 

 multiply, so that in the course of three months the beef tea would 

 be filled with germs of tuberculosis. In growing the bacilli in 

 beef tea, a certain poison was produced, the product of their 

 growth, which is the essence of tuberculin. After three months 

 the beef tea was sterilized by heat, filtered through a porcelain 

 filter which filtered out all the solid matter, then the beef tea 

 was evaporated somewhat, and we have the imported tuberculin. 

 It is beef tea that contains the products of the growth of the 

 tubercle bacillus. It contains no living germs, no germs at all. 

 It is a simple chemical substance that has been produced by the 

 germs, and the beef tea in which they have grown. 



