310 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



fidelity on the part of the men and the nitrogen in the urine de- 

 termined. Thus, we have sufficient data with Squad A to indicate 

 the general picture of the nitrogen balance throughout the entire 4 

 months. With Squad B the conditions were much more satisfactory 

 from the experimental standpoint. The men were on the diet for a 

 period of only 20 days, there were no days of uncontrolled diet, and 

 the balance between the nitrogen intake and the nitrogen output may 

 be definitely determined. 



In any final summation of the nitrogen balance for the period of 4 

 months during which the experiment continued, the nitrogen intake 

 during these unrestricted Sundays and the holiday periods must be 

 taken into account. On 5 uncontrolled Sundays the men made reason- 

 ably close estimates of the food taken. These records are given with 

 the computed energy and nitrogen content in table 34. It might be 

 assumed that the amounts of nitrogen ingested on the uncontrolled 

 Sundays could be taken as an index of the nitrogen intake on the 

 Thanksgiving and Christmas hoUdays, but it is by no means certain 

 that this would be a legitimate assumption. From the reports of the 

 men regarding their dietetic habits during these vacations, it is clear 

 that the high rate of nitrogen ingestion on the uncontrolled Sundays 

 was by no means continued through the entire vacation periods. The 

 fact that the men were morally obligated to return to college at or near 

 their last recorded weight certainly acted as a deterring influence 

 upon excessive consumption. It does not, therefore, seem justifiable 

 to us to assume an average intake of 16.62 grams of nitrogen for each 

 day not specifically noted in our tables between September 27 and 

 February 3. 



It may be seen, however, that any nitrogen balance which may be 

 made without taking into consideration the nitrogen intake of these 

 days will undoubtedly be defective in that the apparent intake of 

 nitrogen will be perceptibly lower than the real intake. On the other 

 hand, the record of the output of nitrogen when measured by the 

 nitrogen of the urine and feces is also deficient in that the urinary and 

 fecal analyses take no note of the loss through the skin, perspiration, 

 epithelial debris, growth of hair and nails, etc. Evidence with regard 

 to the loss through the skin with normal individuals has been some- 

 what extensively discussed elsewhere.' In this earlier study it was 

 found that on the average with men during complete muscular rest, 

 living a restricted life inside the respiration calorimeter, about 0.1 gram 

 of nitrogen per 24 hours was excreted through the skin. During severe 

 muscular work with free perspiration the experimental data showed 

 that there may be as much as 0.22 gram of nitrogen excreted per hour. 

 As may be seen from the record of the physical activity of the men in 



1 Benedict, Journ. Biol. Chem.. 1906. 1, p. 263. 



