Pertinent in this connection is Hawk's[214] statement that young mothers should refrain from the use of coffee, as caffein stimulates the action of the kidneys and tends to bring about a loss from the body of some of the salts necessary to the development of the unborn child as well as for the proper production of milk during the nursing period. The caffein of coffee also increases the flow of milk, but the milk produced is correspondingly dilute and a later decreased secretion may be expected. Furthermore, some of the caffein of the coffee may pass into the mother's milk, thus reaching the child, so that the use of coffee during the nursing period is undesirable on this ground also. Naturally, the question arises as to whether this arraignment is purely theoretical or based upon analytical and clinical data. It is a difficult matter definitely to set an age below which coffee should not be drunk, as the time of reaching maturity varies with climate and ancestral origin. Yet, from a theoretical standpoint, children before or during the adolescent period should be limited to the use of a rather small amount of tea and coffee as beverages, as their poise and nerve control have not reached a stage of development sufficient to warrant the stimulation incident to the consumption of an appreciable quantity of caffein. _Coffee Drinking and Longevity_ There are many who would have us believe that the use of coffee is only a means toward the end of quickly reaching the great beyond; but it is known that the habitual coffee drinker generally enjoys good health, and some of the longest-lived people have used it from their earliest youth without any apparent injury to their health. Nearly every one has an acquaintance who has lived to a ripe old age despite the use of coffee. Quoting Metchnikoff[215]: In some cases centenarians have been much addicted to the drinking of coffee. The reader will recall Voltaire's reply when his doctor described the grave harm that comes from the abuse of coffee, which acts as a real poison. "Well", said Voltaire, "I have been poisoning myself for nearly eighty years." There are centenarians who have lived longer than Voltaire and have drunk still more coffee. Elizabeth Durieux, a native of Savoy, reached the age of 114. Her principal food was coffee, of which she took daily as many as forty small cups. She was jovial and a boon table companion, and used black coffee in quantities that would have surprised an Arab. Her coffee-pot was always on the fire, like the tea-pot in an English cottage (Lejoncourt, p. 84; Chemin, p. 147).