TUBERCULIN -WHAT IT IS; HOW IT IS USED; WHAT 



IT DOES. 



BY PROF. JAS. B. PAIGE, VETERINARIAN TO THE BOARD. 



What it is. 



Tuberculin is the sterilized and filtered glycerine extract 

 of the bacillus tuberculosis. It contains an active principle, 

 chemically complex in its composition, which is produced by 

 the functional activity of the germ. 



The first step in its preparation is the cultivation in the 

 laboratory upon suitable nutrient material of large numbers 

 of the germs. These by their growth produce the active 

 principle. The culture is then treated with glycerine, fil- 

 tered through porcelain to remove the living germs, after 

 which it is sterilized by being subjected to the action of a 

 high temperature. To make it more concentrated, a part of 

 the fluid is evaporated at a low temperature, and carbolic 

 acid added as a preservative. 



By the process of filtration and sterilization all germs in 

 the culture are either removed or destroyed, while the 

 product of their growth remains active in the tuberculin. 



As the active principle is not living matter, and can in no 

 way produce such, the injection of tuberculin into the system 

 of a healthy animal cannot by any possible means give rise 

 to the disease tuberculosis. 



HOW IT IS USED. 



To be accurate, the temperature of the animal to be tested 

 should be taken several times, at intervals of two or three 

 hours, during the day, by inserting into the rectum an or- 

 dinary fever thermometer. The last reading should be taken 



