MILK IN THE DIET

1. As is well understood, milk is the liquid that is secreted by the
mammary glands of female mammals for the nourishment of their young. The
word milk as it is commonly used, however, refers to _cow's milk,_
because such milk is employed to a greater extent as human food than the
milk from any other animal. Cow's milk in its perfectly fresh raw state
is a yellowish-white, opaque fluid, called _whole milk,_ and, as is well
known, possesses a distinctly sweet taste and characteristic odor. When
such milk is allowed to stand for some time without being disturbed, it
separates into two distinct layers, an upper and a lower one. The upper
layer, which is lighter than the lower one and occupies a smaller space,
consists largely of globules of fat and is called _cream;_ the lower
layer, which is white or bluish-white in color and is composed of water,
solids, and protein, is, when separated from the cream, called
_skim milk._

2. As an article of diet, milk is very important, because its sole
function in nature is to serve as food. It is required by the infant; it
is needed in the diet of all growing children; and it is desirable in
the preparation of dishes for both young and old.

Milk is used to such a great extent because it fills many of the
requirements of an ideal food. It is generally liked, requires little or
no time for preparation, agrees with the majority of persons when used
properly, and contains substances that supply energy and build and
repair tissue. Still, it does not contain these substances in such
proportions as to make it an ideal or exclusive article of diet for
adults, and it must often be modified to suit the needs of infants,