CHAPTER X. 
THE BACTERIA IN WATER AND MILK. 
The Bacteria in Milk. 
From its appearance and taste little can be known 
of the bacterial content of milk. It may be teeming 
with bacteria, yet give no indication of their presence. 
In fact, ordinary market milk contains from 100,000 
to 1,000,000 bacteria in every cubic centimeter. 
How do these bacteria get into the milk ? In the 
udder of the healthy cow the milk is practically free 
from bacteria, but they live in the milk-ducts in the 
teats, and get into the milk as it is drawn. The chief 
source of bacteria in milk lies in the uncleanly methods 
of collecting it. Many get it from the dust-laden air 
of the stable, from the dirt on the hide of the cow, 
unclean milk-pail and from the dirty hands of the 
milkers. It is a true saying that the number of bac¬ 
teria in milk is an index of the cleanliness with which 
it has been collected. Once in the milk, the bacteria 
multiply with great rapidity, for milk is an excellent 
medium for the cultivation of bacteria. The tempera¬ 
ture of the milk for some time after it is drawn also 
favors their development. 
To prevent the contamination of milk with exces¬ 
sive numbers of bacteria, all that is required is cleanli¬ 
ness,—clean stables, clean cattle, milkers with clean 
(109) 
Preven¬ 
tion of 
contam¬ 
ination 
