AGRICULTURA.L EXPERIMENT STATION. 127 



able difliculty in the impossibility of discovering cases until con- 

 siderable advance had been made. Diseased cattle might remain 

 in a herd for years and their true condition not even be suspected. 

 Although nearly every state has enacted laws for the purpose of 

 controlling or exterm nating bovine tuberculosis no apparent head- 

 way has been made. There would seem to be as many tuberculous 

 cattle now as ever. To be sure no serious attempt has been made 

 to thoroughly exterminate the disease in any large territory for it 

 has been a recognized impossibility at d it is doubtful if the results 

 from the work done have justified the expense, whether they have 

 or not is certainly open to discussion. The destruction of an ani- 

 mal that has already thoroughly infected her surroundings with 

 disease germs and with only a short natural leave of life 

 remaining may be of doubtful importance. 8he has probably 

 already done most of the harm she is capable of. With the dis- 

 covery of tuberculin and its effects upon tuberculous cattle we 

 entered upon a new era. What was before so nearly impossible as 

 to discourage effort becomes comparatively easy and it will be 

 strange if during the next ten years we do not see more advance 

 made in getting rid of bovine tuberculosis by the aid of the diag- 

 nostic properties of tuberculin than would have been possible in 

 any length of time if dependence had to be placed on a physical 

 examination. In regard to the value of the tuberculin test in 

 diagnosing tuberculosis there can now be no question. The only 

 wonder now is that there should be any opposition to its use or that 

 dependence should longer be placed in a physical examination. 

 But extreme conservatism or ignorance of the comparative value 

 of the tuberculin test probably accounts for it. It is my purpose 



in this report to review some of the results obtained by the use of 

 tuberculin as compared with a physical examination. Our own 

 experience in the use of tuberculin covers more than three years. 

 We have held autopsies on thirty-two cows, heifers and bulls that 

 reacted under the test, and, although we claim a fair degree of skill 

 in making a physical diagnosis, there were not over ten of these 

 animals that we would have condemned from a physical examination 

 alone, yet with possibly two exceptions they all exhibited tuberculous 

 lesions. In two cases where it was necessary to hold a very hasty 

 autopsy by lantern light no lesions were found. At the state college 

 of Pennsylvania the college herd was given a physical examination, 

 and tested with tuberculin, by two different parties. Only one case of 

 tuberculosis was found by a physical examination, and four by the 



