No. 4.] TUBERCULIN. 343 



fluid and can then be forced out by pressing upon the piston 

 until the solution appears at the point of the needle. 



The quantity of tuberculin to be used depends upon con- 

 dition, and varies from 1 to 3 cubic centimeters of the 10 per 

 cent mixture. The dose for an average-sized cow is about 

 2.5 cubic centimeters, while 1 cubic centimeter would be 

 sufficient for a yearling. 



If the animal is suspected of being tuberculous on account 

 of unthriftiness and emaciation, a comparatively large quan- 

 tity should be used, as it has been found in many casesthat 

 animals in the advanced stages of tuberculosis do not respond 

 to the test as readily as those in the early stages. 



It is best to administer the tuberculin during the latter 

 part of the day, when the temperature is normally highest. 

 After it is used the animal should be kept as quiet as 

 possible in the stable for at least twenty-four hours. During 

 this time but small quantities of food or water should be 

 allowed, and all treatment that would tend to cause excite- 

 ment should be carefully avoided. After a period of six 

 hours has elapsed, following the injection of the tuberculin, 

 the temperature should be accurately taken at intervals of 

 two or two and one-half hours for twenty-four hours, count- 

 ing from the time the injection was made. 



What it does. 



The value of tuberculin as a diagnostic of tuberculosis in 

 cattle depends upon the fact discovered by Dr. Koch in his 

 employment of it as a cure for tuberculosis in persons ; that, 

 when injected into the body of a tuberculous patient, its use 

 is followed by the development of febrile symptoms, the most 

 constant and noticeable of which was a rise of the internal 

 temperature. When employed in a similar manner upon one 

 not a subject of the disease, no marked alterations of the 

 normal functions occurred. 



As an illustration, the following tables are introduced to 

 show what might be expected in case of the use of tuberculin 

 upon two cows, one of which is healthy, the other tubercu- 

 lous : — 



