132 Report oF THE BACTERIOLOGIST OF THE 
or not used at all. It should be remembered that some of the 
organisms which are often found in milk will successfully with- 
stand boiling for some hours and the sterilization, in the true 
sense, of any commercial quantity of milk at a single heating is 
a practical impossibility unless temperatures above that of boil- 
ing water are used. 
THE TWOFOLD APPLICATION OF PASTEURIZATION 
EO MITE EK 
The subject of the pasteurization of milk has been presented 
to the American public with reference to two distinct problems 
—the sanitary milk supply of cities and the production of uni- 
formly good butter. 
While heat is appled in both cases the methods of application 
which have been found most successful in each are radically 
different and an attempt to accomplish either object by the other 
process has not yet been shown to be practical. The first method 
is too slow and expensive to be adapted to butter making and the 
second plan when carried on at a temperature sufficiently high 
to kill the tubercle bacillus gives an objectionable flavor to the 
milk. Fortunately this flavor does not remain in the butter. 
THE DISCONTINUOUS OR HOUSEHOLD SYSTEM. 
About ten years ago when the use of tuberculin was bringing 
home the alarming prevalence of tuberculosis among our dairy 
cows and the danger of transmission of the disease to invalids 
and children through milk seemed self-evident, pasteurization 
was brought forward as a safeguard from this danger. In this 
method the milk was heated at a definite temperature for a defi- 
nite length of time. 
At first 67.8°C. (155°F.) for 20 minutes was advocated, but 
owing to the change brought about in the viscosity of the milk and 
