The question suggests itself, why, if food is constantly supplied, naturally or otherwise, does the body lose in weight? The answer is found in the fact that the intake is not digested, consequently is not assimilated, and, far from nourishing the tissues, is an added burden to functions already overtaxed. Another cause is discovered in that brain and nerve tissue, as instruments for the expression of thought and sensation, are protected from deterioration in substance, even in disease, by a provision of nature that permits them to utilize nourishment stored in the interstices of body tissue. This they consume in illness and in health, and, when in disease a normal balance is not preserved, when cells are not rebuilt as waste occurs, they still are supported from this source.
With slight differences the physiology of digestion in all mammals is markedly similar. When disease is manifest, the lower animals and the reptiles abstain from food until health is restored. They are compelled to this by instinct, a force implanted by nature in the whole of animate creation. The fasting which animals instinctively undergo is a fact that is constantly observed, but not in general mtelligently perceived. A common
