DISEASE GERMS IN MILK. l6l 
strange that these products, containing as they do, bacteria reckoned 
by the hundreds of millions per c.c., should be recommended as 
beverages for infants and invalids. A glassful of well soured 
milk will certainly contain 100,000,000,000 bacteria, and yet it 
is a wholesome as well as a refreshing beverage. The explanation 
however, is simple enough. These myriads of bacteria are practically 
all of the type of lactic acid bacteria, which are not only harmless 
in themselves, but which prevent the growth of various kinds 
of putrefactive germs that might produce trouble in the intestine. 
The presence of a goodly number of lactic acid bacteria, therefore, 
may prevent the growth of certain types of intestinal putrefaction 
that would otherwise cause trouble. The farmer's belief that 
butter-milk and sour milk are healthful drinks, which seemed hardly 
credible for a while when the immense numbers of bacteria contained 
in them were first recognized, appears, after all, to be well founded 
on scientific fact. The use of such milk is becoming recommended 
very widely, and already there are on the market commercial prepa- 
rations of lactic bacteria to be used in preparing such milks. These 
preparations, as a rule, contain the particular form of lactic bacteria 
mentioned on page 148 which has the characteristic of being more 
vigorous, and making milk more acid than the ordinary lactic acid 
bacteria, and, therefore, having in even greater degree this power of 
preventing the growth of other more mischievous organisms. The 
healthful properties ascribed to the alcoholic beverages mentioned 
on page 158 are probably due to the presence of the beneficent 
lactic acid bacteria. 
DISEASE GERMS IN MILK. 
It has long been recognized that milk may be a distributer of 
disease. This general statement is disquieting, but the knowledge 
is of little use unless it can be made more definite. The subject 
can be made more intelligible if we notice what kind of diseases 
are thus distributed and how the dangers arise. There are four defi- 
nite diseases known to be distributed in this way, and, in addition, 
a less definite type of intestinal trouble. 
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