_Aids to Digestion._--It is only during the last part of the Nineteenth Century that the world has learned how to live. “What is one man’s food is another man’s poison” has been a trite old saying for many years, but the reason why has only in late years been fully understood. The physiology of digestion, the relative digestibility of different articles of food, and their nutritive values, have received of late years the earnest attention of physicians and students of dietetics and have contributed much to the quality and kind of food, and a knowledge of when and how to eat it. We know that the starchy foods are digested by the saliva, which is an alkaline digestion; that meat, fish, eggs, cheese and the albumenoids are digested in the stomach by the gastric juices (pepsin and hydrochloric acid) which is an acid digestion, and that the remaining portions of starch, the sugars, and fats are digested in the intestines, and that this is also an alkaline digestion, and this has helped to solve the problem for us. We also know that starch is an excellent food, provided the vital powers are sufficiently stimulated by fresh air, sunlight, and exercise to digest it, as do the horse and the ox when they eat corn, but we know furthermore that the sedentary occupations of modern life leave many stomachs in a condition unable to assimilate starch, and so bread, oatmeal, potatoes and such simple staples, instead of nourishing the body, ferment in the enfeebled stomach, produce acids and gas, and lay the foundation for serious chronic diseases. The student of chemistry and dietetics knows to-day that one part of diastase will effect the conversion of 2,000 parts of starch into grape sugar, as a preliminary step to its digestion, and so by treating starchy matter with substances containing diastase (derived from malt) a partial transformation is effected which will materially shorten and assist its digestion. This fact has been largely made use of in the preparation of easily soluble or pre-digested foods, examples of which are found in patent to Horlick (malted milk), No. 278,967, June 5, 1883; to Carnrick (milk-wheat food), Dec. 27, 1887, No. 375,601; and Boynton and Van Patten (cereals and diastase), 344,717, June 29, 1886.