fats are found in nuts, especially the pecan, cocoanut, Brazil, and
pine nuts; also in the grains, particularly oats and corn. The peanut
also contains a considerable amount of fat. Of the fruits, the banana
and strawberry contain a trace of fat, while the olive is the only
fruit rich in fat.

As a food, fat is used in three forms. The emulsified form is
represented by cream, olive oil, and nuts. When the tiny globules of
fat, which are each surrounded by a little film of casein, are
crushed--united into a solid mass--we have a free fat. This form is
represented by butter and other animal fats. Another form is fried
fat--fat which has been chemically changed by heat with the
development of certain irritating acids.

MINERAL SALTS

The mineral elements comprise but a small part of human food as
regards weight, but they are extremely important to the health of the
child as well as the adult. As found in the food, they are not in the
form of mineral salts, like common table salt. The salts of food are
living salts, organic or organized salts, such as are found in the
growing plant. These salts are of great value to the various fluids
of the body, and also as stimulants to nerve action, but more
particularly in the work of building up the bones.

Salts are found largely in the cereals. A small amount is also found
in vegetables, particularly the potato, as well as in most fruits.

CELLULOSE

Cellulose represents the great bulk of all vegetables and fruits. It
is digested by most animals, but in man it is digested only to the
extent of about thirty per cent. The presence of a large amount of
cellulose in the food enables us often to satisfy the appetite without
injury from overeating. It serves to give bulk to the food, and
thereby possibly acts as a preventive to constipation.

WATER

Water fills an important place in the nutrition of the body. The food
changes in connection with digestion, assimilation, and elimination,
can take place only in the presence of water. Water constitutes from
fifteen to ninety-five per cent of the various foods. The watery
juices of vegetables and fruits consist largely of pure, distilled
water, in which fruit sugar is dissolved, with added flavoring
substances. Water is absolutely essential to the performance of every
vital function connected with human metabolism.

ANIMAL HEAT

The source of heat in the animal body was the subject of much
superstitious speculation on th