THE USEFUL MICROBES 
39 
made up of many little balls, or drops, of fat, 
floating in the water which is the liquid part 
of the milk. They give the milk its familiar 
white color. These little drops of fat are made 
up of several substances that are of great value 
as food for the human body. 
Besides the drops of fat, we always find many 
different kinds of microbes in milk. There 
are some in the freshest milk, and the older the 
milk becomes, the more plentiful are the 
microbes, for milk is one of the best things for 
their growth. Some of the microbes were in 
the cow that gave the milk, but by far the 
greatest number got into it from the skin of 
the cow, from the hands of the person that 
milked her, from the buckets which held the 
milk, and from the dust in the dairy barn. 
Because milk is such a suitable material for 
their growth, the microbes multiply in it 
rapidly, especially if it is kept at ordinary heat. 
If it is kept cold, however, the number of 
microbes soon becomes less; so you can see 
how important it is to chill the milk as soon 
Under the microscope ^ 
we see that mil\ is made 
up of many little balls, 
or drops of fat 
What is in 
milk? 
o Q/O^ 
Drops of fat 
