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.**° He was among the 
first, if not the first, in America to recognize the value of the 
Bang Method in treating valuable herds.1* 
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’® 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 
done commercially up to 1900 was rarely satisfactory. 
In 1898 Theobald Smith’? published his studies on the 
thermal death point of the tubercle bacillus showing that in 
laboratory tests the germ of tuberculosis was killed in milk 
by a heating at 140° F. for 15 minutes. Studies?® 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. 
16 See footnote 8. 
1747. L Russell, The History of w Tuberculous Herd of Cows, Bulletin 
78, Wis. Agr. Exp. Sta., 1899. 
1%. LL, Russell, Pasteurization of Milk and Cream for Direct Con- 
sumption, Bulletin 44, Wis. Agr. Exp. Sta., 1895. 
19 Theobald Smith, The Thermal Death-point of Tubercle Bacilli in Milk 
and Other Fluids in Jour. Exp. Med., 4, pp. 217-233, 1899. 
2» FW. LL, Russell and E. G. Hastings, Thermal Death-point of Tubercle 
Bacilli under Commercial Conditions in Annual Report, Wis. Agr. Exp. Sta., 
17 (1900), pp. 147-170, 1900. 
