have not yet been sufficiently perfected to enable accurate and rapid determination to be made of all these individual carbohydrates, and hence they are grouped together as nitrogen-free-extract. As the name indicates, they are compounds which contain no nitrogen, and are extractives in the sense that they are soluble in dilute acid and alkaline solutions. The nitrogen-free-extract is determined indirectly, that is, by the method of difference. All the other constituents of a food, as water, ash, crude fiber (cellulose), crude protein, and ether extract, are determined; the total is subtracted from 100, and the difference is nitrogen-free-extract. In studying the nutritive value of foods, particular attention should be given to the nature of the nitrogen-free-extract, as in some instances it is composed of sugar and in others of starch, pectin, or pentosan (gum sugars). While all these compounds have practically the same fuel value, they differ in composition, structure, and the way in which they are acted upon by chemicals and digestive ferments.^[1]