Although the net caloric intake has been shown on the individual body-weight curves, the average values for these 9 men are here given in blocks closely associated with the average body-weight curve. The difficulty of securing evidence regarding the net caloric intake at the maintenance weight level is more clearly brought out in this composite curve than with the individual curves, for one would expect a smoothing of the curve, indicating even more than is here shown that weight maintenance was obtained in December and again in the latter part of January. Even with the best possible food adjustment, which it will be recalled was specifically planned to maintain the weight at a constant level, we find that the average value for the 9 men shows considerable fluctuation. Yet we see no reason for altering our original statement that during December and the latter part of January these men were essentially at weight maintenance. As was pointed out in the earlier discussion, a change of 1 kg. may not be significant, owing to the large water content of the body, and it is by no means a certain indication of changes in organized body-tissue. The energy intake at the weight level is for the December period 2,200 calories and for the January period 1,950 calories. The average for these 9 men for these two periods is therefore 2,075 calories, which is but little above the average value for the entire squad, namely, 1,967 calories.

It is important to note that in this chart, as in the individual body-weight charts, the net energy intake for the first few days in October, which is here represented as 3,100 calories, should in all probability be nearer 4,000 calories, and would in consequence normally occupy a higher block and correspond more nearly to the general trend of the body-weight curve.

In spite of the striking changes in the net energy intake, as shown by the blocks at the bottom of the chart, the nitrogen in the food represents fluctuations by no means comparable to the total energy. The general contour of the series of blocks indicates that the nitrogen of the diet was not on a particularly low level, but averages about 10.5 grams. The section of the curve for the last few days of the experiment shows a distinctly high nitrogen intake, this being higher than at any other time during the observation, save for the first week of uncontrolled normal diet.

In striking contrast to the nitrogen in the food is the rather level curve for the nitrogen in the urine; that is, in spite of the relatively enormous alterations in nitrogen in intake, we find the nitrogen in urine remains reasonably constant, the lowest point of the curve appearing a few days following November 26. Here again it is well to emphasize the fact brought out in the study of both Squads A and B that the relative constancy of the nitrogen excretion in the urine under very marked change in intake is one of the surprising features of the research.

The comparison between the nitrogen of the food and the nitrogen in urine leads, of course, to the consideration of the large nitrogen losses. These are so significant and of such magnitude that we have deemed it advisable to plot them in the form of a curve showing the accumulative nitrogen loss, which is a curve that continues downward as the experiment progresses. This appears near the lower part of the chart and shows a final loss at the end of the experiment of not far from 175 grams of nitrogen for the average of 9 men. Sufficient attention has been called in the earlier text to the difficulties of accurately estimating the total nitrogen loss, owing to the uncontrolled days, on the one hand, and to the loss through the skin and perspiration on the other.

One of the most important physiological measurements showing general condition is the blood pressure, which is frequently reported with these men. The average blood-pressure curves show systolic, diastolic, and pulse pressure. All three curves have much the same trend, namely, a distinct falling off up to November 25, with a tendency for minimum values appearing shortly thereafter, then a slight rise in systolic and diastolic pressure to January 12, after which, although the systolic and diastolic pressure curves are parallel, the pulse pressure is in the opposite direction. Pronounced reductions of all three factors are worthy of special emphasis.

Pulse-rates were recorded frequently throughout the entire series under several conditions. The normal pulse-rate was observed with the subject lying in the morning in the post-absorptive condition. (See lower part of figure 124.) The curve shows a distinct tendency towards a fall in the first part of the experiment, a plateau at the low level in November, a sharp fall from a higher level following the Christmas recess, and a slight rise toward the end of the experiment.

The important relationship between the pulse-rate and muscular work is indicated by the records computed from Professor Johnson's data, with the subject lying 1 minute before work, 1 minute after work, and the percentage increase 1 minute after work. The pulse-rate 1 minute before work, although at a distinctly higher level, is obviously more or less comparable with the pulse-rate obtained in the morning with the subject in the post-absorptive condition. The form of the two curves is not unlike, the pulse-rate 1 minute before work showing a decrease in the early part of the experiment, followed by a pronounced rise, with a striking increase immediately after the diet restriction ceased. This great increase was followed by a distinct drop following more normal eating.

The pulse for 1 minute after work on the ergometer shows up to December 8 very much the same trend as do the other pulse-rate curves. On December 10 there is a large increase and immediately following the return from the Christmas recess there is a pronounced fall to the end of the restricted-diet period. The striking increase after the restricted diet ends, noted with the pulse 1 minute before work, is here even more accentuated.