Examining the data in table 37, we find that the energy of the food per day with Squad A averaged not far from 2,000 calories after the first week. With Squad B, it will be recalled, the energy of the food was cut down on the average to not far from 1,500 calories, and it was possible so to adjust the food intake that practically all 12 men received the same amounts of energy and nitrogen. The digestion period extended from January 15 to 23 (nearly twice as long as most of the digestion periods with Squad A). This long period gave an admirable opportunity for a satisfactory separation and for a study as to what proportion of nitrogen and total energy will appear in the feces when identically the same amounts of food materials are passed through 12 different digestive tracts. The data for Squad B are given in table 38, from which it can be seen that the nitrogen per day in the food varied only from 7.34 grams to 8.54 grams, with an average of 8.21 grains. The nitrogen in the feces varied from 0.53 gram to 1.40 grams, with an average of 0.89 gram. It is perhaps of significance that the lowest value (0.53) appeared with Ham, who likewise had the lowest nitrogen intake. The so-called digestible nitrogen ranged from 6.81 to 7.64 grams, with an average of 7.32 grams. The nitrogen utilized varied only from 83 to 93 per cent, with an average of 89 per cent. Special attention should be given to the fecal nitrogen, for we have here conditions which are exactly comparable to those of Professor Chittenden's earlier research.1 In the 6-day digestion period with Professor Chittenden's soldiers from January 12 to 17, 1904, an average of 49.4 grams of nitrogen was ingested by each subject, while the nitrogen in feces varied from 4.45 to 12.10 grams, with wide variations from the average (8.46 grams) in a majority of cases. Similar irregularities were noted in the digestion period from February 29 to March 6, 1904, and likewise from March 28 to April 1, 1904, although in this latter period the agreement was much closer. These experiments of Chittenden strongly suggest a disturbance of digestion with low diet, and it is difficult to account for the irregularity of the values. With our squad of 12 men such abnormalities did not appear, even though the nitrogen intakes were actually somewhat lower than those in Professor Chittenden's study and in all probability the caloric requirements were somewhat similar. It thus can be stated that with a group of college students on a very greatly reduced diet, disturbances in the proportion of nitrogen utilized were not found. The availability of the energy was not far from that found with Squad A, being on the average 87 per cent. The agreement among the men was remarkably constant, the widest variation being from 86 to 89 per cent. These men used on the average 25 grams of bran per day. The uniformity of the figures, both for nitrogen and energy, indicate that with a group of 12 men the same amount of food passing through 12 different digestive tracts results in a strikingly uniform degree of absorption, even when an extraordinarily low diet is being taken.

1 Street, Coon. Agr. Expt Sta. Ann. Rep.. 1914. p. 243.

Table 38. - Nitrogen Utilized And Energy Available From Food In Digestion, Period With Reduced Diet - Squad B

1 Chittenden, Physiological economy in nutrition, New York, 1907 (first issue, 1904), p. 131; ■ee, also, in this connection, Benedict, Am. Journ. Physiol., 1906, 16, p. 420.