Sugar is a concentrated form of nourishment that especially gives strength to muscles and helps to produce fat. It has long been known to be a strength producer, but its value was not fully appreciated until demonstrated by Morro with the aid of the myograph, an instrument that records the amount of work done by a muscle or group of muscles. He found that sugar in food in not too great quantities and not too concentrated lessens or delays fatigue and increases working power. Vaughan Har-ley and others have confirmed these results by repeated experiments. When muscles are wearied by hard work, they can be revived by a meal of sugar with great rapidity and to a noticeable degree. The effect of sugar on muscular work is demonstrated a half hour after meals, but is greatest two hours after. Tests of its value confirming these laboratory experiments of Morro and Harley have been made upon soldiers, athletes, and others who were submitted to hard muscular work.

Sugar is more quickly utilizable by the body than is starch. It is adapted for use in infancy when starch cannot be digested and in some dyspeptic states. It produces fat as well as strength, and may be prescribed or forbidden as one desires to put on fat or lose it. If used in too large quantities it will cause indigestion. Harley took nearly a pound daily without injury except to the stomach. Three or four ounces can be taken daily by an adult without harm. If too much is taken, it will not be held by the liver but will enter the blood in abnormally large amounts and be rapidly excreted by the kidneys. This is called a dietetic or alimentary glycosuria and is temporary. If such glycosuria is persistently or frequently provoked, it will cause pathologic conditions. All forms of sugar do not produce glycosuria with equal readiness. Hutchison found that it was provoked by the following kinds, with the amounts given in this table:

The readiness with which glycosuria is provoked varies also in different persons.

Large quantities of sugar or of sweetened food are likely to ferment in the stomach and intestines, producing alcohol and acids that may excite inflammation in those organs. Aitchison Robertson found that different sugars vary in their susceptibility to fermentation.

The following undergo lactic acid fermentation with relative ease in the order in which they are named: Levulose, most fermentable, lactose, dextrose, invert sugar, cane-sugar, maltose. The following list shows the relative ease with which butyric acid fermentation can be provoked: Levulose, most fermentable, maltose, dextrose, invert sugar, cane-sugar, lactose. The following shows the relative ease with which alcoholic fermentation is produced: Maltose, invert sugar, cane-sugar, dextrose, levulose, lactose. It is noticeable that lactose is least likely to undergo any of these forms of fermentation, which makes it especially useful when we wish to avert them. Dyspeptics should use sugar sparingly. Many of them cannot use it even in tea and coffee without discomfort.

Sugar should be taken well diluted. Nature furnishes it in milk and most fruits in very small proportion - rarely more than from 4 to 6 per cent. Experience teaches us that it is best borne by stomach and bowels when taken in this way. Candies and food upon which a syrup is used, and compotes that are very sweet, are often indigestible because they contain sugar in concentration. There is no evidence substantiating the popular notion that sugar causes the teeth to decay. Undoubtedly if starch is allowed to cling long to the teeth or to accumulate in the interstices between them it will ferment and produce acids that may be harmful. If the mouth and teeth are kept clean, it will not produce these results.

Cereals are the grains that are used for food. They contain relatively little cellulose, much starch, and variable amounts of oil, gluten, and mineral matter; the exact chemical composition varying in different species. Cereals are rarely eaten until they have been crushed or ground to a powder. The outer layers form bran, which consists chiefly of cellulose and is extremely difficult to convert into flour. By modern milling processes the germ as well as the bran is removed from the flour. The former contains a relatively large amount of nitrogenous matter and oil. It easily becomes rancid, and flour containing it may spoil. The proteins can convert some of the starch of flour into dextrin and sugar, which will render bread made from it darker in color than is agreeable. The following table, from Hutchison, shows the composition of the different parts of the grain:

The best grades of wheat flour are to-day made from the endosperm. The compositoin of flour from various cereals is given in the subjoined table, taken from a report of the United States Department of Agriculture.

To utilize flour as food it must be cooked. The simplest way is to boil it. However, only the coarser meals are cooked in this way. Usually they are eaten with cream or milk and sugar. Flour can be mixed with water, rriolded into definite form, and baked. It is in this way that ship biscuits are made. Primitive races cook flour only in this way. The product is hard, difficult to break and to disintegrate with the teeth, and as much of it is likely to be swallowed before it is perfectly masticated, it is not easily digested.

Bread is the chief food-product of flour. It is made by mixing flour with water and adding a little salt and sometimes sugar. Yeast is added to the mixture, which is then set aside in a warm place. The yeast-cells grow and convert some of the starch into sugar and then into alcohol and carbonic acid gas. This gas fills the dough with bubbles, which make it light and spongy. The fermentation ceases when the bread is baked. The yeast is killed, and most of the alcohol and gas is driven off. In this process a small amount of nutriment is also lost. One and three-tenths per cent, of the proteins, 71.2 per cent, of the fats, and 3.2 per cent, of carbohydrate are lost, or about 5 per cent, of the calories that might be generated from the flour. To avoid this loss two processes are used. In the first, which is rarely resorted to, the dough is 'aerated' by gas produced outside and forced into it. In the second, the more common process, baking-powders are used. They consist of mixtures of powdered chemicals which, when wet or mixed with moist dough, liberate carbonic acid gas.