The rower in a college crew requires six weeks of training before his muscular power and endurance have reached their height. Every particle of superfluous fat must be removed, for fat is not strength, but weakness. There is a vast difference between the plumpness of good muscular development and the flabby, heavy overloading of these muscles with rolls of fat. The chest must be enlarged, that the lungs may have full play, and be capable of long-continued, extra draughts upon them; and special diet and special exercise alone can accomplish these ends. All fat-producing foods are struck out, sugar and all starchy foods coming under this head, as well as all puddings, pies, cakes, and sweets in general. Our boy, after a short run, would breakfast on lean, under-done beef or mutton, dry toast, or the crust of bread, and tea without milk or sugar; would dine on meat and a little bread and claret, and sup on more meat and toast, with cresses or some acid fruit, having rowed twice over the course in the afternoon, steadily increasing the speed, and following it by a bath and rub. At least nine hours sleep must be had; and with this diet, at the end of the training-time the muscles are hard and firm, the skin wonderfully pure and clear, and the capacity for long, steady breathing under exertion, almost unlimited. No better laws for the reduction of excessive fat can be laid down for any one. Under such a course, severe mental exertion is impossible; and the return to it requires to be gradual. But light exercise with dumb-bells, &c., fresh air, walking, and good food are the conditions of all sound mental work, whether done by man or woman. For the clerk or bookkeeper closely confined to desk or counter, much the same regimen is needed, with brisk exercise at the beginning and end of the day,--at least always walking rather than riding to and from the office or store; while in all the trades where hard labor is necessary, heartier food must be the rule. And for all professions or trades, the summing-up is the same: suitable food, fresh air, sunlight, and perfect cleanliness,--the following of these laws insuring the perfect use of every power to the very end. As old age advances, the food-demand lessens naturally. Nourishing food is still necessary, but taken in much smaller quantities and more often, in order that the waning powers of the stomach may not be overtaxed. Living on such principles, work can go on till the time for work is over, and the long sleep comes as quietly as to a tired child. Simple common-sense and self-control will free one once for all from the fear, too often hanging over middle life, of a paralytic and helpless invalidism, or the long train of apoplectic symptoms often the portion even of middle life. I omit detail as to the character and effects of tea, coffee, alcohol, &c, such details coming in the chapters on the chemistry of food. CHAPTER X. THE CHEMISTRY OF ANIMAL FOOD.