282 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



lulKTcular lesions in animals. On the otlici- hand, cxpcrinK'ntal 

 evidence concerning; the transniissihility of" hos inc InluTciilosis iu 

 mau is necessarily \vantin<r. Tlic preponderance of authoritative 

 oj)inion at the present time. howcNt'i-, supports tin' l<>n<;-held view 

 that i)ovine tuberculosis is a source of danp'r to hinnan life. 



That the tubercle bacillus may be present in the milk of affected 

 cows before the disease can be reco«>-nized by ])hysical signs has been 

 repeatedly demonstrated. Ernst" found tubercle bacilli pi-eseiil and 

 active in a very large proportion of cases showing no discoverable 

 lesion of the udder. Law ** rejjorted the contraction of the disease by 

 calves nursed by cows with apparently sound udders, but having 

 general tuberculosis. Kussell and Hastings'" recorded additional 

 experiments demonstrating by means of animal inoculations the 

 infectiousness of the milk of tuberculous cows showing no discover- 

 able udder lesion. 



The early recognition of tuberculosis in cows therefore becomes of 

 great inqiortance. The most valuable means of securing this is the 

 tuberculin tests of Koch, to the establishment of wl^ch, as a ])ractical 

 and reliable diagnostic agent, nearly every experiment station in this 

 country has contril)uted l)V tests too numerous to cite. 



In experiments on nontuberculous coavs Law '' found that injections 

 of tuberculin did not impair the health of the animals nor affect the 

 yield or the fat content of the milk. General results elsewhere have 

 also demonstrated that the tuberculin test may be applied with perfect 

 safety to healthy animals and their milk used without injurious 

 results. 



In the eradication of tuberculosis from dairy herds manv of the 

 stations have been actively engaged, and recently tests of von Behr- 

 ing's method of immunizing cattle against the disease have been 

 undertaken. Although the milk of cows in the early stages of tuber- 

 culosis may not always be infectious, it is quite generally believed 

 that the best interests of the public demand that no milk from 

 tuberculous cows should be offered for sale, or at least without effi- 

 cient pasteurization. 



Thorough veterinary inspection of dairy animals is doubtless the 

 l)est means of ascertaining any existing danger of transmitting 

 disease from cows to milk consumers. AVhile it is not always possible 

 to secure such supervision with the elimination of diseased animals 

 from dairy herds, some efforts have been made to devise means of 

 examining milk for the purpose of detecting any abnormality which 

 might point to the presence of disease in cows. Several methods 



o Massachusetts Hatch Sta. Bui. 8, p. 13. 

 6 New York Cornell Sta. P.ul. <;.">, p. 136. 

 <• Wisconsin Sta. Rpt. 1904. p. 172. 

 a New York Cornell Sta. Bui. 82. 



