ghty-seven parts were water and thirteen parts were solid.
These thirteen parts of solids consist of sugar, proteins, and salts;
this is likewise the case with cow's milk, except that in the case of
the cow's milk, the sugar is decreased while the proteins are
increased as will be noted by the accompanying comparative analysis:

MOTHER'S MILK

Fat % 4.00
Sugar 7.00
Proteins 1.50
Salts 0.20
Water 87.30
------
% 100.00

COW'S MILK

Fat % 4.00
Sugar 4.50
Proteins 3.50
Salts 0.75
Water 87.25
-----
% 100.00

Mother's milk is absolutely sterile, that is, free from the presence
of germs; on the other hand, cow's milk is anything but sterile--the
moment it leaves the udder it begins to accumulate numerous bacteria,
all of which multiply very rapidly. Cow's milk is generally
twenty-four to forty-eight hours old before it can possibly reach the
baby. It is just as important to keep in mind these facts of milk
contamination--dirt, filth, flies, and bacteria--as it is to plan for
the modification of cow's milk for the purpose of making it more
nearly resemble mother's milk. While mother's milk has about the same
percentage of fat as cow's milk, it is almost twice as rich in sugar,
and has only one-fourth to one-third as much protein. This protein is
vastly different from that found in cow's milk, which you recall has a
tough curd, as seen in cottage cheese. While mother's milk contains a
small amount of casein similar to that found in the cheese of the
cow's milk, the principal protein constituent is of another kind
(lactalbumin), and is much more easy of digestion than the casein of
cow's milk.

This is a most important point to remember, because the baby's stomach
is not at first adapted to the digestion of the heavier and tougher
protein curds of cow's milk. It requires time to accustom the infant
stomach to perform this heavier work of digestion. There are a number
of factors which must be borne in mind in the modification of milk,
whether it be cow's milk, or goat's milk (for many European physicians
use goat's milk entirely in the artificial feeding of infants):
namely, the cleanliness of the milk, the acidity of milk, the
difference in the curd, the percentage of sugar, and the presenc