The starchy portion is converted, through the digestive ferments in the saliva, pancreatic, and intestinal juices, into dextrin and grape sugar; absorbed through the intestines, it is deposited in the form of glycogen in the liver, the muscles also absorbing a large part of this glycogen. Through work this glycogen is exhausted. Thus work is performed mainly at the expense of the carbohydrates, which are the prime generators of muscular energy. We have also seen that the above-mentioned Japanese coolies perform their incredible muscular efforts largely on such food only. Still, a part of the muscular energy of the body can also be provided by the proteids and fats. Carbohydrate foods, and especially those that are poor in fatty contents, such as rice, and especially potatoes, which are the most deficient of all (having but 0.1 per cent. of fat), necessitate the simultaneous use also of fat; for this kind of exclusively carbohydrate diet would invariably lead to starvation unless there was a plentiful supply of fat with it; and the best and most agreeable form to introduce fat into the body is by means of butter. Butter is very nutritious, as it contains, according to Rubner, 83.1 per cent. of fat, 0.9 per cent. of albumin, and 0.5 per cent. of carbohydrates. One hundred grammes of butter contain, according to Rubner, 779 calories. In addition to the above, butter also contains salts, and from 8 to 12 per cent. of water. A diet rich in carbohydrates could not be well assimilated without butter; but, at the same time, the abundant use of the latter also necessitates the use of carbohydrates, which are the best vehicle for butter; therefore, when in diabetes we prescribe much butter or other fats, we make it a rule, also, to give some kind of food that contains some amount of carbohydrates, such as brown bread or green vegetables, or sometimes, in mild cases, also boiled potatoes. Potatoes, when new and watery, contain 16 per cent. of carbohydrates; when they are old, 22 per cent. In many European countries they form a most important article of diet. Though, as shown in the foregoing table, they contain only 2 per cent. of proteids, they contain also important salts, such as a certain amount of citric acid and citrates of potassium, sodium, and lime. Thus potatoes, by means of these salts, are also an alkaline food, and if consumed in very large quantities, the acidity of the urine can become much diminished. These salts are burned in the body, and the potassium is then transformed into a carbonate salt. Mossé recommends potatoes in large quantities as a preventive of diabetes.