Gradually as adult life advances, the inclina tion and sometimes the power for active exer cise fails. These are evils to be guarded against. Outdoor games, horse-back riding, and vigor ous walking, for example, may be pursued ad vantageously as a rule to 45 or 50 years of age. At about this time degenerative changes occur in the body and care is necessary that the heart and blood vessels be not overstrained. During the prime of life the body enjoys a maximum of vigor and power of endurance, and there is reason to believe that this is also true of the mind. But the self-consciousness of power that the individual possesses is frequently a menace, for it induces him to struggle for wealth or fame in the turmoil and bustle of modern life. to neglect recreation, to resort to alcoholics and other stimulants to keep up his energy, and to indulge in general high living. It is especially true at this time of life that no one should work up to the full measure of his ability. Such work is dangerous and has been responsible for the "breaking down" of the health and the death of many otherwise intelligent persons. The principal diseases of adult life are alcoholism, gout, cancer, urinary and venereal diseases, rheumatism, pneumonia, tuberculosis, affections of the brain and nervous system, of the heart and blood vessels and of the digestive system.
The Period of Old Age or Senility usually commences about the 60th year and is charac terized by a waning of the vital powers and by atrophic and degenerative changes, the natural consequences of decay. While death frequently results from local accidents of the brain and nervous system (apoplexy, sclerosis, etc.) and
of the heart, blood vessels and urinary organs irredeemably damaged in the course of decay, it is normally but the ending of a natural life, and not a pathological fact as in earlier life. The stature of the old is less, the shoulders rounded, bones are more fragile, the cartilages are hardened, the lower jaw resembles that of the infant, the chin is prominent, the skin is wrinkled owing to the absorption of fat, and loses its elasticity, the teeth decay and fall out, urination is frequently difficult, the respirations and heart beats are reduced in frequency, the arteries have a tendency to ossify, the veins to dilate. The muscles tail in their tension, the voice becomes a "childish treble? the digestion is weakened, the eye no longer sees clearly and hearing is dulled. The mind may preserve its freshness for a long time. Usually the senses fail first, next the faculties of memory, reason and volition. Toward the close of life the organic or vegetative phenomena prevail. The natural death occurs when the breath becomes fainter and fainter and the heart beats are weaker and fitful — and then gradually cease.
Old people require an abundance of sleep. They need also to be kept warm, for heat is generated in them in smaller amount than in robust health. Hence they are easily chilled. Food should be plain, largely liquid and that most easily digested. Exercise in the open air every day is desirable but it should be gentle in character. With these precautions old age may be made comfortable. See ADOLESCENCE;