enes.

Hindhede, by arranging a dietary based upon these principles, has
demonstrated that a man may be perfectly sustained on a diet which
contains no animal product of any sort. In a letter received by the
writer from this able Danish physiologist, the statement is made that a
strong laboring man was maintained for 23 months in perfect health and
vigor on a diet into which no animal products entered.

Another important fact developed by Rubner, Mendel, McCollum and other
investigators which is of fundamental importance in animal nutrition, is
that proteins differ in their value as tissue builders. Proteins differ
from the starches and fats in the great complexity of their composition.
Instead of being simple compounds or mixtures of a few simple compounds,
proteins, as found in nature, consist of several sorts of highly complex
molecules which vary greatly in their composition.

The protein molecule is made up of a number of organic units known as
amino acids. There are 30 or 40 different kinds of amino acids of which
less than 20 enter into the formation of the proteins of the human body.
These 18 or 20 different amino acids are absolutely essential for the
formation of body proteins, and are produced by plants, hence if they
are not found in the food the body cannot produce them and the material
necessary for tissue building or repair will be lacking.

Proteins which contain all the amino acids essential for tissue building
are known as complete proteins. Other proteins, lacking in certain
essential constituents, are designated as incomplete: Flesh foods
necessarily furnish complete proteins. The proteins of milk and eggs are
also complete proteins. The proteins met in the vegetable world are
exceedingly varied in character. Each species of plant produces its own
kind of proteins. Vegetable proteins differ greatly among themselves.
Complete proteins are comparatively rare. The proteins of cereals, for
example, have been shown to be deficient in some of the essential amino
acids. The deficiency is still greater in the proteins of beans. In
fact, the proteins of vegetable foods in general may be said to be
deficient.

The necessity for providing the body with complete proteins was
doubtless the original cause which led men under circumstances of
privation and emergency to resort to the use of animal flesh for food.
The cows of Nantucket, the ponies of Alaska, and I have recently been
informed by Mr. Goddard, cura