14 



mals may be purchased, and this may be because of failure to react 

 through " indifference." Indeed, a pure deception might be prac- 

 ticed by the seller who could intentionally cause a tuberculin test to 

 be made shortly before the sale. A protection against such danger 

 may easily be established by requiring that every reacting animal 

 shall be provided with a permanent mark. Such a requirement is, 

 however, scarcely practicable at the present time, because it would 

 cause the cattle owners a pecuniary loss which, in my opinion, would 

 bring the entire tuberculin question into discredit. Fortunately, the 

 danger is not so very great. The failure of the reaction on repeat- 

 ing the test is by no means constant even when a few days intervene.*^ 

 Intentional deception could therefore be practiced to no great extent. 

 The very cautious cattle owner could hold his newly purchased ani- 

 mals apart from the healthy ones, until an additional test had been 

 made. 



From the uncertainty in the action of the tuberculin, established in 

 various ways, we must necessarily conclude that the tuberculin test 

 is not to be regarded a certain legal proof ; for this we have only, 

 first, the evidence of the tuberculous bacilli, secretions, exudations, 

 or extirpated tissues from living animals, and also, positive results 

 from inoculation experiments with such materials ; and second, dis- 

 section. Clinical investigation, stethoscopy, proof of swollen retro- 

 pharyngeal lymph glands, of a laryngeal tumor projecting forM^ard 

 between the shield and ring cartilages, rectal exploration with proof 

 of hard tumors in the mesenteric glands, the ovarian ducts, the 

 uterus, on the peritoneum, etc.. can in certain instances furnish a 

 probable diagnosis. In such cases there still remains the tuberculin 

 injection. This diagnosis may be considered sufficient to prove 

 tuberculosis, but the tuberculin reaction alone gives, in my opinion, 

 no sufficient proof of the presence of tuberculosis. The negative re- 

 sult from a tuberculin injection yields still less absolute proof of the 

 absence of tuberculosis. 



We will now consider the following question, a very important one 

 in the application of tuberculin, viz : Can the reaction produce a 

 worse condition in tuberculous animals than before existed? Hess 

 emphatically states that it can, and on this account he earnestly 



42. Conijiare Malm. Cm Tuberkulin pp .3i»-42 (Kristiania 18!)4) one cow rcafted 

 distinctly on the 27th of Oct., on the .5th, 17th, and 20th of Nov., and in addition, 

 "With sTuall doses slightly (on the average 1°) on the 30th of Oct., 2d, 7tli, 10th, and 

 13th of Nov. 



