DEVELOPMENT OF CITY MILK SUPPLY PROBLEMS 35 



gle with this disease, a struggle which has continued unabated 

 for twenty-five years and the end is not yet. He promptly 

 concluded that the tuberculin test properly conducted was 

 the best available means of diagnosis. 10 He was among the 

 first, if not the first, in America to recognize the value of the 

 Bang Method in treating valuable herds. 17 



He was quick to recognize the need of some method of 

 rendering the public milk supply safe from the danger of 

 carrying tuberculosis to the consumers. He turned at once 

 to pasteurization 18 as a safeguard and in the succeeding years 

 no more practical method of accomplishing this purpose 

 has been discovered. Pasteurization then labored under the 

 disadvantage that the available data on the thermal death 

 point of the tubercle bacillus called for a time and temperature 

 of pasteurization which seriously impaired the commercial 

 qualities of the milk. As a result pasteurization as it was 

 clone commercially up to 1900 was rarely satisfactory. 



In 1898 Theobald Smith 19 published his studies on the 

 thermal death point of the tubercle bacillus showing that in 

 laboratory tests the germ of tuberculosis w r as killed in milk 

 by a heating at 140 F. for 15 minutes. Studies 20 were im- 

 mediately begun at Wisconsin which showed that under com- 

 mercial conditions the germs in question were killed by ex- 

 posure to 140 F. for 10 to 15 minutes thus substantiating the 

 findings of Smith. It was recommended that in commercial 

 plants the heating be continued for 30 minutes at 140 F. 

 in order to provide a satisfactory margin of safety. This 

 method of pasteurization has been found satisfactory from 

 the commercial point of view and has become the standard 

 procedure in protecting the milk supplies of the country. 



18 See footnote 8. 



17 H. L Russell, The History of a Tuberculous Herd of Cows, Bulletin 

 78, Wis. Agr. Exp. Sta., 1899. 



18 H. L. Russell, Pasteurisation of Milk and Cream for Direct Con- 

 sumption, Bulletin 44, Wis. Agr. Exp. Sta., 1895. 



"Theobald Smith, The Thermal Death-point of Tubercle Bacilli in Milk 

 and Other Fluids in Jour. Exp. Med., 4, pp. 217-233, 1899. 



20 'H. L. Russell and E. G. Hastings, Thermal Death-point of Tubercle 

 Bacilli under Commercial Conditions in Annual Report, Wis. Agr. Exp. Sta., 

 17 (laOO), pp. 147-170, 1900. 



