296 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



The indigestible bran in the diet unquestionably raised perceptibly 

 the true undigested food material in the feces, and undoubtedly ac- 

 counts, in part at least, for the low value for available energy noted with 

 some of these men. And yet it is a fact that, using the two illustra- 

 tions cited in discussing the nitrogen data, Gar and Mon on December 

 10 to 15, when the energy of the food with each subject was about 

 3,000 calories, there is actually a slightly larger value for available 

 energy in the case of Mon, although Gar had no bran and Mon had 168 

 grams. While this discrepancy is strikingly opposed to the general 

 belief that the presence of bran in the diet would tend to lower the 

 available energy, and one must realize that, after all, a relatively small 

 proportion of bran is indigestible,^ nevertheless bran was in most 

 instances an added food and contained a definite amount of un- 

 hydrolyzable material. It would thus normally be expected to 

 lower the energy available. In practically all studies on reduced 

 diet low values for available energy are found. Those noted here 

 are well within normal limits and we have no reason to question 

 the influence of the restricted diet upon the digestive processes of 

 these men. 



One great difficulty, encountered in this research, was the tendency 

 for the reduced diet to produce constipation, this making the separa- 

 tion of feces difficult. With Pec, whose abnormal defecation has 

 been commented on frequently in this report, no accurate separation 

 could be obtained between November 29 and December 10, although 

 three or four attempts were made, and only approximate values are 

 recorded in table 55. (See p. 334.) 



DIGESTION EXPERIMENT WITH SQUAD B ON GREATLY REDUCED DIET. 



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 re- 

 ceived 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 

 grams. 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 



^ Street, Conn. Agr. Expt. Sta. Ann. Rep., 1914, p. 243. 



