DISEASES OF CATTLE 257 



such treatment will facilitate a better comparison between the sev- 

 eral protective methods against tuberculosis that were tested. 



The tuberculous environment to which the animals used in these 

 experiments were exposed was a large cow stable with an adjacent cow 

 yard. In this stable and yard the infection was provided by a num- 

 ber of cattle affected with advanced tuberculosis, of which it was defin- 

 itely known that they were freely expelling tubercle bacilli. In the 

 yard into which the cattle were turned daily for from 2 to 8 hours, 

 depending upon the state of the weather, all the cattle treated, checks 

 and diseased, were allowed to mingle as they chose ; in the stable the 

 cattle were made to occupy stalls in such rotation that the exposure of 

 the different individuals was equalized as much as possible. 



The dates on which the 10 calves were killed and a short memo- 

 randum of the lesions found on autopsy follow: 



No. 444, treated but not exposed reacted to tuberculin October 

 17, 1907 (13 months after last bovo-vaccination injection). Killed 

 November 7, 1907. No lesions found, but firm pulmonary adhesions 

 and one small glistening nodule, 3 mm. in diameter, in the lung. No 

 tubercle bacilli on microscopic examination or animal inoculation 

 were found in the minute glistening nodule, which may have been a 

 small healed tubercle caused by bacilli from one of the intravenous 

 injections. 



No. 427, killed April 23, 1908, after having been exposed to a 

 tuberculous environment for about 18 months. No lesions of 

 tuberculosis. 



No. 432, killed March 9, 1909, after having been exposed to a 

 tuberculous environment over 2 years. No lesions of tuberculosis. 



No. 429, killed July 16, 1909, after having been exposed to a tu- 

 berculous environment over 2 years. No lesions of tuberculosis. 



No. 435, killed April 10, 1909, after having been exposed to a tu- 

 berculous environment over 2 years. One post-pharyngeal gland 

 twice the normal size and almost entirely tuberculous. No other 

 lesions. 



No. 431, killed March 25, 1909, after having been in a tubercu- 

 lous environment almost 2 years. Mediastinal glands contained a 

 number of minute necrotic foci which failed to show the presence of 

 tubercle bacilli on microscopic examination and guinea-pig inocula- 

 tion. Lungs contained a number of minute areas which had the ap- 

 pearance of healing tubercles ; no bacilli found in these areas. 



No. 436, killed March 29, 1909, after having been in a tubercu- 

 lous environment almost 2 years. No lesions of tuberculosis. 



No. 438, killed April 10, 1909, after having been in a tubercu- 

 lous environment over 2 years. No lesions of tuberculosis. 



No. 441, killed April 9, 1909, after having been in a tuberculous 

 environment over 2 years. Autopsy showed minute lesions in the azy- 

 gos lobe of lung and a small focus 3 mm. in diameter in the right 

 prescapular gland, no tubercle bacilli found in the lung lesions. The 

 prescapular lesions showed tubercle bacilli on microscopic examina- 

 tion and guinea-pig inoculation. 



