PRACTICAL APPLICATIONS 381 



ten times, and the dose varies from 4 c.c. for a large bull to i c.c. 

 for a calf under one year. The temperature is taken for a day or 

 two before the injection, and at the ninth, twelfth, fifteenth, and 

 eighteenth hours afterwards. The rise is gradual, reaching its 

 maximum in twelve to fifteen hours, and then falling gradually to 

 normal. According to Nocard, anything over 2*5 F. is diagnostic, 

 from i '4 to 2-5 F. suspicious, and under i'4 F. unimportant. The 

 temperature of the animal should not exceed 103 F. when the 

 injection is made. 



Von Pirquet's reaction or the cutireaction : This was introduced 

 as a method of avoiding the dangers supposed to be incidental to 

 the use of tuberculin sub cute. A very gentle scarification of the 

 skin is made, just as for Jennerian vaccination, avoiding drawing 

 blood, if possible, and the abraded surface covered with diluted 

 tuberculin (i part with 3 of normal saline containing 0*25 per cent, 

 carbolic acid). A control scarification is made, preferably on the 

 other arm, and covered with the carbolized normal saline solution. 

 The reaction takes the form of a red papule of varying size, 

 sometimes extending for -| inch or more in all directions from the 

 site of the original scarification. I have seen the skin so sensitive 

 that a vivid reaction was obtained where the diluted tuberculin 

 had accidentally run down the skin. The redness increases for a 

 day or two, and may remain for four or five days, but in general 

 disappears earlier. It is to be compared with the control side, 

 which has also been treated with dilute carbolic acid, but no 

 tuberculin. Von Pirquet now uses undiluted tuberculin, the 

 control scarification not being treated at all. This is probably 

 the better method, and seems devoid of danger. In Moro's 

 method an ointment containing tuberculin is rubbed into the skin. 



The process is probably quite devoid of danger. Some tuber- 

 culin is certainly absorbed, since I have seen a quite definite local 

 reaction round a tubercle in the iris ; the temperature, however, 

 does not usually rise, but may do so ; this is a sign that the 

 scarification has been too deep. No reaction is given in advanced 

 cases of the disease, probably because the resisting powers are 

 too low for the production of the necessary antibodies. The 

 same, it may be noted, is true for the ordinary tuberculin test, 

 if it were ever justifiable to use it in such cases. 



Of the value of the test there is no doubt, and a well-marked 

 reaction is conclusive. A good deal of difficulty arises from 

 slight and doubtful reactions, and it sometimes appears to fail in 



