INFECTIOUS DISEASES OF CATTLE. 415 



ltitely fallacious. The tuberculin does not contain the tubercle bacillus, and it is 

 absolutely certain that it is impossible to produce a case of tuberculosis in an 

 animal unless the tubercle bacilli are present. The use of tuberculin, therefore, 

 certainly can never produce the disease in the inoculated animal. 



It has been more widely believed, however, that the inoculation of an animal 

 vrith this material has a tendency to stimulate an incipient case of tuberculosis. 

 It has been thought that an animal with a very slight case of the disease may, 

 after inoculation, show a very rapid extension of this disease and be speedily 

 brought to a condition where it is beyond any use. The reasons given for this 

 have been the apparent activity of the tuberculosis infection in animals that have 

 been slaughtered shortly after inoculation. This has been claimed, not only by 

 agriculturists who have not understood the subject well, but also by veterinarians 

 and bacteriologists. But here too, we must recognize that the claim has been 

 disproved, and that there is now a practical unanimity of opinion on the part of 

 all who are best calculated to judge, that such an injurious effect does not occur. 

 Even those who have been most pronounced in the claim that there is injury thus 

 resulting from tuberculin have, little by little, modified their claim, until at the 

 present time they say either that the injury which they formerly claimed does 

 not occur, or that the stimulus of the disease is so slight that it should be abso- 

 lutely neglected, in view of the great value which may arise from the use of tuber- 

 culin. Apart from two or three who hold this very moderate opinion, all bacte- 

 riologists and veterinarians unite in agreeing that there is no evidence for believ- 

 ing that any injury results. In Denmark, especially, many hundreds of thousands 

 of animals have been inoculated, and the veterinarians say there is absolutely no 

 reason in all their experience for believing that the tuberculin inoculation is fol- 

 lowed by any injurious results. 



In 1898 tuberculosis was found in the large Shorthorn herd belong- 

 ing to W. C. Edwards, of Canada, who with commendable promptness 

 and public spirit had his animals tested, and at once proceeded to 

 separate the diseased from the healthy animals. These were all finely- 

 bred animals, and the very class which we have been told are most 

 susceptible to the injurious effects of tuberculin. After using this 

 test regularly for two years, Mr. Edwards wrote as follows : 



I have seen nothing to lead me to believe that the tuberculin test had any inju- 

 rious influence on the course of the disease. It is by no means our opinion that 

 the disease has been stimulated or aggravated by the application of the tuberculin 

 test. All animals that we have tested two or three times continue as hale and 

 hearty as they were previously, and not one animal in our herds has broken down 

 or failed in any way since we began testing. 



Mr. Edwards, in December, 1901, verbally stated to the writer that 

 his views as to the harmlessness of tuberculin remained \mchanged, 

 and that he had not seen the least ill effect with any of his cattle from 

 its use. 



Those who have had most experience with tuberculin have failed to 

 observe any injurious effects following its use upon healthy cattle. 

 With tuberculous cattle it produces a fever of short duration, and in 

 the great majority of cases all derangement of the system which it 

 causes disappears within forty-eight hours after the tuberculin is 

 administered. There appear to have been a very few cases in which 

 the disease was aggravated, and a greater number in which it was 



