WE have seen in the first chapter of this book that we may find the symptoms of old age, in quite early years, in persons whose ductless glands (the thyroid, ovaries, testicles, liver, kidneys, pancreas, adrenals, pituitary body) are degenerated by disease; nervous affections; alterations of the mind: grief, sorrow, etc.; chronic infections; numerous pregnancies, etc., or by faulty hygienics: excesses in food, alcohol, sexual pleasures, etc. We have also seen in the third chapter that the immunity of an individual against infections—be it by bacterial invasion or by poisonous food or drugs, etc.—is dependent upon the correct functionating condition of these glands. We have seen that those in whom these glands are degenerated fall easy victims to all manner of infections, and the previous chapter on heredity shows that the same happens to children, the offspring of parents suffering from alcoholism, tuberculosis, or malaria, as the children of these parents are born with a congenital degeneration of the thyroid, and thus remain backward in growth, both mentally and physically, and, especially, fall easy victims to tuberculosis. Their life is generally short. While such a sad cloud hangs over the head of persons whose glands are damaged, either congenitally or by disease, much more favorable is the lot of those who have inherited healthy glands and by careful living have preserved them intact, or who, though born with ductless glands not entirely normal, and possibly bordering on a condition of congenital myxœdema, have, by suitable treatment and hygiene, succeeded in improving the condition of their glands. We have seen that the thyroid influences powerfully the production of those safeguards of our body against infections—the anti-bodies being, as shown by Prof. Sajous (1903-1907), beyond a doubt products of ductless glands—and the better the condition of the glands, the more protective substances will be produced in order to fight down the murderous microbes, or organic poisons, which continually threaten us with destruction. In this fight, a person with healthy ductless glands will always attain a longer life than one with ductless glands of inferior quality. The better the condition of the thyroid the greater will be the activity of those organs that are under its direct command (e.g., the kidneys, liver, skin, and intestines), and by the increased activity of the main emunctories of the body poisonous products will be eliminated by means of a greater flow of urine, an abundant perspiration, and thorough purging. Also the myriads of toxic products that are brought from the intestine to the liver will be promptly destroyed, or transformed into less dangerous combinations. Thus there can be no doubt that a person with healthy ductless glands, especially the thyroid and testicles or ovaries, will live long provided, of course, no other vital organ be irreparably diseased.