While the statistics for Gul show no consistently lower output of nitrogen, save perhaps subsequent to November 22, nevertheless even this change was not profound, and it seems advisable to consider how the low diet affected the squad as a whole. It has already been shown that the intake of nitrogen was not in all cases alike. In general, however, the average intake was not far from the same for the entire squad, both in total calories and in total nitrogen. This is shown more in detail in certain other tables.1

Although this is not the specific place to discuss the relationship between the intake and output of nitrogen, with special reference to the nitrogen balance, several features of the first 12 days of the experiment justify our reproducing here the figures for the total nitrogen in urine for this period and likewise for a period of 12 days from December 5 to 18, when the squad was essentially on maintenance diet at the lower level. (See tables 41 and 43.) The nitrogen in the food for the first 10 days in the experiment and for December 5 to 18 are also given in tables 40 and 42. Considering the nitrogen in the urine during the first 12 days of the experiment (table 41), we find that fluctuations occur not only between different men, but that the same man shows differences from day to day. The lowest nitrogen output is almost invariably shown by Tom. The total nitrogen output per day for the 12 men averages not far from 145 to 150 grams for this period.

1See tables 46 to 68. pp. 312 to 341.

Table 40. - Total Nitrogen In Food During First 10 Days Of Experiment - Squad A

Samples were not obtained of the diet on September 28 and 29.

Table 41. - Total Nitrogen In Urine Per 24 Hours During First 12 Days Of Experiment - Squad A

Table 42. - Total Nitrogen In Food During 13 Typical Days After Long Diet Restriction - Squad A

Table 43. - Total Nitrogen In Urine Per 24 Hours During 12 Typical Days After Long Restricted Diet - Squad A

1 The urine samples for December 16 were frozen in transit, and it was thus impossible to obtain the nitrogen output for this day.

The total nitrogen intake at this time (table 40) is of special interest, since it gives us an indication of the first reduction in diet, which took place on October 4. Prior to this, although the subjects were requested to eat as freely as they normally would, we find that the nitrogen intake was surprisingly uniform with all men on October 1, 2, and 3, when the men were on an unrestricted diet. It is clear that any difference in intake for these 10 days must have been in the nonprotein food materials, for these men had essentially the same protein intake. Indeed, the daily intake for the individual men is almost exactly the same save on October 1. This comparison of data presents an interesting physiological study, however, inasmuch as we have here 12 men, each of whom took practically the same daily amount of nitrogen as the others for a period of approximately 10 days, and yet the nitrogen excretion varied somewhat widely for the corresponding days. Thus, on October 9 Pea and Tom, with essentially the same nitrogen intake, i. e., 12.21 and 12.05 grams, respectively, have a nitrogen output in the urine of 15.53 grams for Pea and 10.73 grams for Tom. The striking fall in the nitrogen intake for the whole squad on October 4, amounting to over 60 grams, was accompanied by a fall of 16 grams in the total nitrogen in the output. On the whole the nitrogen output for the 12 days is reasonably constant, although the nitrogen intake was greatly decreased after the first 3 days for which we have a record of the food.

Another point which should be brought out is the fact that the nitrogen of the intake was by no means definitely fixed each day, but depended somewhat upon the character of the food served generally to the men. Thus, we find a marked rise from an average of 9.33 grams on October 7 to 13.82 grams on October 8. This is a good illustration of the lack of positive control of nitrogen intake; in other words, the nitrogen intake was not predetermined.

If we examine the nitrogen excretion in the 12 days from December 5 to December 18 (table 43) we note again rather striking irregularities, which are even greater than those noted for the October excretion, minimum figures of about 6 grams appearing in several instances. On the other hand, we have but to examine the nitrogen intake on the corresponding dates (see table 42) to find somewhat wide variations, which may, in part, account for some of the variations in the nitrogen in the urine. These two sets of tables, however, give a fairly good picture of the differences in nitrogen intake and nitrogen excretion observed with Squad A prior to the reduction in the diet and again at the lower level when they had approximately a maintenance diet.

Disregarding the individual variations found on the different days and taking the averages for the group, we may consider the total nitrogen excretion per man per 24 hours as illustrated in these specimen tables. On the first 12 days of the experiment, that is, from September 28 to October 10, inclusive, we find the average nitrogen excretion to be 12.19 grams of nitrogen per day (see table 41). The averages for the individual days do not vary widely from this total average, the highest daily average being 13.15 grams on October 3 and the lowest average, singularly enough on September 29, 10.53 grams, this being the last day on which the diet was uncontrolled, for the feeding at the diet table was not begun until the morning of October 1. Taken as a squad, therefore, the urinary excretion is surprisingly uniform.

The average daily excretion of nitrogen for the squad in the later period of the experiment, namely, from December 5 to December 18, inclusive, when the subjects had approximately a maintenance ration, at least so far as caloric intake was concerned, is shown in table 43. The average nitrogen excretion for the entire 12 days was 10.92 grams per man per day. The variations in daily averages are somewhat larger than in the earlier part of the experiment, for here they range from 9.80 grams on December 14 to a maximum of 12.21 grams 3 days later, but are reasonably uniform, the average value, 10.92 grams, being a little over 1 gram less than the average value found for the first 12 days of the research. In other words, we see clearly that we deal with no large variations in the daily excretion of nitrogen, considering the squad as a whole.