DISEASES OF CATTLE 259 



No. 413, killed August 9, 1909, after having been exposed to 

 a tuberculous environment over 2 years. No lesions of disease. 



No. 426, killed April 1, 1909, after having been in a tubercu- 

 lous environment over 2 years. Lungs were found to contain a 

 few very minute tubercles. 



No. 428, killed March 29, 1909, after having been in a tuber- 

 culous environment nearly 2 years. No lesions of tuberculosis. 



No. 430, killed March 22, 1909, after having been in a tuber- 

 culous environment nearly 2 years. The pleura and mediastinal 

 glands show minute lesions closely resembling tuberculosis, but no 

 tubercle bacilli could be found in these lesions by microscopic exam- 

 ination or guinea-pig inoculation. 



No. 433, killed July 16, 1909, after having been exposed to 

 a tuberculous environment about 2 years. No lesions of tubercu- 

 losis. 



No. 442, killed July 16, 1909, after having been exposed to 

 a tuberculous environment about 18 months. No lesions of tuber- 

 culosis. 



No 440, killed April 10, 1909, after having been exposed to a 

 tuberculous environment nearly 18 months. No lesions of tuber- 

 culosis. 



VACCINATION BY SUBCUTANEOUS INJECTION. 



Injections into the End of the Tail. As the earlier inves- 

 tigations of the Bureau of Animal Industry on the subject of pro- 

 tective inoculations against tuberculosis had given results indi- 

 cating that the degree of immunity conferred by the injection of 

 living tubercle bacilli into the bodies of cattle depended rather 

 upon the virulence of the injected bacilli than upon the method 

 of injection or the number of injections, a series of tests was made 

 relative to the effects from injecting cattle with quite virulent tu- 

 bercle bacilli into a portion of the body (the end of the tail) from 

 which the infection, with its strong tendency to become localized, 

 would have to move some distance before it could reach its favor- 

 ite location in the body. The end of the tail also offered the ad- 

 vantage that the character and process of the inoculation disease 

 could be watched and that treatment, surgical if necessary, could 

 be applied. 



On June 20, 1906, the following 4 calves received each a sub- 

 cutaneous injection, immediately above the brush at the end of 

 the tail, of 3 c. c. of a suspension of bovine tubercle bacilli. The 

 tubercle culture used was "Bovine III," and each 3 c. c. of the sus- 

 pension was equal to 0.01 gram of tubercle bacilli. 



Heifer calf No. 447, about 3 months old; Heifer calf No. 

 448, about 3 months old; Bull calf No. 450, about 3 months old; 

 Bull calf No. 451, about 2M> months old. 



The tuberculous disease caused in the tails of the animals 

 varied considerably. In one case, No. 447, it was necessary to 

 amputate the tail. The four animals were exposed to a tubercu- 

 lous environment beginning some time after the protective injec- 



