AS a general rule the first symptoms of old age do not appear before the fortieth or forty-fifth year. There are, however, many persons who, much earlier, occasionally even before thirty, show some of the typical symptoms of senility: corpulence, gray hair, wrinkles in the face, falling out of the hair and loss of teeth, etc., for example. The gums also are retracted from the teeth, which consequently appear greatly lengthened; later on the teeth become loosened and fall out. This then causes the jaw bones to atrophy, when the face becomes sunken, and the individual appears many years older. The hair loses its original color and becomes dry and gray, especially on the temples. The appearance of bald spots surrounded by gray hair increases the aged appearance of the face. On examination, the pulse of such persons may exhibit a high tension, the temporal arteries may be tortuous, and the skin found to be dry. A sensation of cold in the extremities is especially frequent. There is, as a rule, a tendency to constipation. The mental faculties are also altered; the memory weakens, and the mind is often depressed. Neurasthenia or hysteria become frequent in such persons, while impotence in men and menstrual disorders in women develop. The urine may be found to contain traces of albumin and occasionally a few hyaline casts. The presence of these, according to Professor Senator,[1] indicates a degeneration of the convoluted tubules of the kidneys, and thus the loss of important elements of the chief excretory organ of the human body. Footnote 1: Hermann Senator: “Die Erkrankungen der Nieren;” Nothnagel’s “Handbuch der praktischen Medicin,” ii Auflage, 1902. On examination of the state of nutrition in these persons, it may often be found to be below the normal. It is certain that such a condition in young people is abnormal, and, therefore, a pathological condition. The question now arises: In which category of diseases is this condition to be classified? In typical cases of this class there is a diminution of metabolism, i.e., of the assimilation and conversion of food into energy. We shall have to think of the possibility of alterations in those organs which govern the process of metabolism. These organs are the glands with internal secretion (especially the thyroid gland, testicles, ovaries, the adrenals and pituitary body), according to recent researches, among which those of the author of this book may be mentioned. He was among the first to show the fact that glands with internal secretion control all the processes of oxidation,[2] and that the diseases of metabolism: diabetes, obesity, gout, etc., are the direct consequence of alterations in these important glands. This is further sustained by the labors of Sajous[3] who was the first to describe the mechanism through which these organs govern oxidation and metabolism, and to explain how they produce the disorders just enumerated. Footnote 2: