must be assimilated. The forces manifested by the body, the muscular forces, or nervous energy, are the result of the breaking down of organized structure into simpler forms. For example, in the case of nervous energy, material from which nerve energy is derived is stored up in the nerve cell, and can be seen with the microscope in the form of minute granules, which disappear as the cell energy is expended, leaving the cell blank and shriveled when in a state of extreme fatigue from overwork. The same is essentially true of the muscle cell. The source of muscular energy is glycogen, an organized substance which becomes a part of the muscle tissue in a well-nourished muscle in a state of rest.
"Experiments have clearly shown that fat, sugar and starch must all alike be converted into the form of glycogen and enter into the muscle structure before they can become a source of energy.
"Professor Atwater tells us that alcohol can not form tissue, hence the query is pertinent, How can it be a source of vital energy? The body does not burn food as a stove does fuel. Food can be called fuel only in a highly figurative sense. The oxidation of food in the body does not take place directly. Food is assimilated, becoming a part of the tissue. Oxygen is also assimilated, entering into the composition of the tissue along with the food elements under the action of special organic ferments brought into play by nervous impulses received from the central ganglia.
"The molecules of these residual tissues which form the storehouse of energy in the body are rearranged in simpler forms, thereby giving up a portion of the energy which holds them together in the state in which they exist in the tissues, and this energy thus set free appears as muscle force, mental activity, glandular work and various other forms of functional activity."
