THE BACILLUS OF TUBERCULOSIS 305 



phthisis, laryngeal tuberculosis, and other tuberculous processes no 

 effects have been noted, and nearly everyone disapproves of their use 

 in these cases as well as in those where mixed infection is suspected; 

 even in cases of beginning infection, opinions, as a whole, are not very 

 enthusiastic. The new tuberculin, unless prepared with great care or 

 from tubercle bacilli, which are non-virulent for man, is apt to be a 

 dangerous substance. Trudeau, Baldwin, and others found that with 

 the first product sent out guinea-pigs injected with it not only did not 

 become immunized, but actually became infected from the living bacilli 

 in the fluid. 



Diagnostic Use of Tuberculin. The chief use to which tuberculin has 

 been put is as an aid to the diagnosis of tuberculosis in cattle and human 

 beings, and for this purpose it has proved to be of inestimable value. 

 Numerous experiments made by veterinary surgeons show that the 

 injection of tuberculin in tuberculous cows in doses of 25 to 50 

 centigrams produces in at least 95 per cent, a rise of temperature of 

 from 1 to 3 C. (2 to 5 F.). The febrile reaction occurs in from 

 twelve to fifteen hours after the injection. Its intensity and duration 

 do not entirely depend upon the extent of the tuberculous lesions, 

 being even more marked when these are slight than in advanced cases. 

 In non-tuberculous animals no reaction occurs, or one much less than 

 in tuberculous animals, and the results obtained on autopsy justify 

 the suspicion that tuberculosis exists if an elevation of temperature of 

 a degree or more centigrade occurs and remains for ten hours from 

 the subcutaneous injection of the dose mentioned. It must always be 

 remembered that cattle may have a rise of temperature from other 

 conditions, and it is only when due to tuberculin that infection is proved. 

 When properly carried out an error of more than 5 per cent, is impossible. 

 For these injections the original tuberculin is used, which for the con- 

 venience of administration is diluted with water. 



United States Government Directions for Inspecting Herds for Tubercu- 

 losis. "Inspections should be carried on while the herd is stabled. If 

 it is necessary to stable animals under unusual conditions or among 

 surroundings that make them uneasy and excited, the tuberculin test 

 should be postponed until the cattle have become accustomed to the 

 conditions they are subjected to, and then begin with a careful physical 

 examination of each animal. This is essential, because in some severe 

 cases of tuberculosis, on account of saturation with toxins, no reaction 

 follows the injection of tuberculin, but experience has shown that these 

 cases can be discovered by physical examination. This should include 

 a careful examination of the udder and of the superficial lymphatic 

 glands, and auscultation of the lungs. 



"Each animal should be numbered or described in such a way that 

 it can be recognized without difficulty. It is well to number the stalls 

 with chalk and transfer these numbers to the temperature-sheet, so 

 that the temperature of each animal can be recorded in its appropriate 

 place without danger of confusion. The following procedure has been 

 used extensively and lias given excellent results: 



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