Tuberculosis in Cattle. 27 



of tuberculosis in a herd were not put in force. The cows were 

 not taught to keep the same stall on all occasions, but went into 

 any stall that was convenient. Then there were no partitions 

 between the feeding places of adjacent stalls and one cow could 

 lick up the food from the two stalls on the right and left as well 

 as from her own. With an infecting cow in the herd, therefore, 

 there was every opportunity for a speedy spread of the infec- 

 tion. In spite of such obvious opportunity^ for infection the care- 

 ful selection of the first members of the present herd, the build- 

 ing up of the herd by home breeding only, and the weeding out 

 of all suspicious animals succeeded in excluding any trace of 

 tuberculosis. 



The experiment, however, entailed the entire destruction of 

 the original infected herd, and though the post mortem exami- 

 nation showed that in this instance this step was necessar}^ to a 

 successful result yet in many other less universally diseased 

 herds the larger part could have been saved by picking out the 

 diseased with the aid of the tuberculin test. 



2d. In Cornell University herd, which numbers about sixty 

 cattle, old and young, tuberculosis led to the destruction of a 

 number of individuals. The diseased, however, were disposed of 

 as soon as objective symptoms showed the presence of tuberculo- 

 sis, and after some years of this weeding out when I tested the 

 whole herd with the newly discovered tuberculin I could find no 

 trace of the disease except in a young bull which had recently 

 been acquired from another herd. Since his destruction I have 

 tested them repeatedly, but have found no trace of tuberculosis. 



KXTIXCTIOX OF TUBERCULOSIS WITH THE AID OF 



TUBERCULIN. 



If a herd has been bred up from home stock without the intro- 

 duction of an}' animal from without, and if for a number of 

 years there have been no losses and no illness suggestive of any 

 form of tuberculosis there is a fair presumption that it is free 

 from that disease. But in the average herd, and especially if 

 sickness or death has occurred, even if such has been attributed 

 to something else, it is a wise precaution to subject the whole 



