Within the large intestine bacterial action goes on fully as vigorously as in the small, and because of the smaller relative amounts of digestible food and of water a much larger proportion of the intestinal contents consists of the bodies of the bacteria and of the products of their metabolism. Since the sugars have been completely absorbed out by the time the food reaches the large intestine and the remaining materials upon which the bacteria can feed are more largely of the protein class, the bacterial action changes from fermentation to that which we commonly describe as putrefaction. This type of action, instead of giving rise to alcohol and carbon dioxide, produces a number of highly offensive compounds; many of these can pass through the lining membrane of the large intestine into the blood and so can circulate around the body. Of late years we have realized that these products of intestinal putrefaction are highly poisonous, especially if present in the blood stream in any considerable amount. The term “auto-intoxication,” which we run across frequently in health literature, means strictly the poisoning of the body by the products of intestinal putrefaction. Of course, the condition is much aggravated if putrefaction is allowed to go on for too long a time. The ill feelings which result from constipation and which in the life of very many people constitute a really serious impairment of health are the direct result of poisoning by these putrefaction products. The obvious remedy is the avoidance of intestinal sluggishness; unfortunately this is easier in theory than it often is in practice. Probably two conditions of modern life are chiefly responsible: the first is our tendency to make the diet more and more highly concentrated; that is, to leave out of it more and more the indigestible parts. The result is that not enough indigestible material enters the large intestine to make a sufficient bulk upon which the intestinal muscle can work in moving the mass forward. While bulk is accumulating, both absorption of water and putrefaction are going on, until by the time a sufficient mass is present, it is so dry that the muscles are not able to move it along and it has produced undue quantities of poisons. Obviously the way to treat this condition is by eating more indigestible material. For this purpose there is nothing better than apples in their season. The old proverb “An apple a day keeps the doctor away” has very sound common sense back of it. Apples are not ideal for this purpose for all people, since they frequently cause a distressing evolution of gas or even headache. Nearly everybody, though, by experimenting, can find a time of day at which an apple can be eaten without any digestive trouble whatever, and frequently with considerable benefit. Apples are valuable simply for their bulk of indigestible substance. The process of cooking converts most of this into digestible material, so that for this particular purpose they must