Unlike fats and carbohydrates, proteids are not burned completely in the body; hence, the physiological fuel value of a proteid is less than the value obtained by oxidation in a bomb calorimeter. In the body, proteids yield certain decomposition products which are removed through the excreta, and which represent a certain quantity of potential energy thus lost to the economy. The average fuel value of proteids burned outside of the body is placed at 5711 calories per gram,[3] or 5.7 large calories. Deducting the heat value of the proteid decomposition products contained in the excreta, the physiological fuel value of proteids is reduced on an average to about 4.1 large calories per gram.[4] Rubner considers that the physiological fuel value of vegetable proteids is somewhat less than that of animal proteids; conglutin, for example, yielding 3.96 calories, as contrasted with 4.3 calories furnished by egg-albumin, or 4.40 calories from casein. On a mixed diet, where 60 per cent of the ingested proteid food is of animal origin and 40 per cent vegetable, the fuel value available to the body would be about 4.1 calories per gram of proteid, on the assumption that the physiological heat value of vegetable proteids averages 3.96 calories per gram and that of animal proteids 4.23 calories per gram (Rubner). [3] Stohmann: Ueber den Wärmewerth der Bestandtheile der Nahrungsmittel. Zeitschr. f. Biol., Band 31, p. 373. [4] See Rubner: Calorimetrische Untersuchungen. Zeitschr. f. Biol., Band 21, p. 250. Also, Rubner: Die Quelle der thierischen Wärme. Ibid., Band 30, p. 73. At present, we accept for all purposes of computation the following figures as representing the physiological or available (to the body) fuel value of the three classes of organic foodstuffs: 1 gram of proteid 4.1 Large Calories 1 gram of fat 9.3 " " 1 gram of carbohydrate 4.1 " "