On several of the uncontrolled Sundays the subjects admittedly ate very large amounts of food.1 Furthermore, as was shown in the discussion of the body-weight measurements (see p. 210), all of the subjects increased in weight perceptibly during the Christmas vacation and were on a rather free diet. The influence upon the basal metabolism of these excess feeding periods may be sharply noted in practically all instances on the return of the men to college in January 1918. In a number of instances the gaseous metabolism was also perceptibly increased on the Monday mornings following a Sunday with uncontrolled diet.

An examination of the values obtained in the morning respiration experiments with the respiratory-valve apparatus shows the effect of the excess food on the metabolism. The oxygen consumption may be used alone for this purpose, as the changes in the respiratory quotient are such as not to affect materially the heat production. Thus, on December 3, after the Thanksgiving recess, Pea had an average oxygen consumption in two periods of 209 c.c. per minute, as compared with an oxygen consumption of 192 c.c. on November 22, and of 195 c.c. on December 13. (See table 123, page 508.) With Pec, on October 29, after the uncontrolled Sunday of October 28, the oxygen consumption was 242 c.c, the highest value for the oxygen consumption obtained for this subject with the respiratory-valve apparatus in this research. Prior to this experiment the oxygen consumption was (October 24) 206 c.c. Before the reduction in diet, the one value obtained with Pec on the respiratory-valve apparatus (October 3) showed but 219 c.c.

1 The occasional Sundays when the diet was more or less uncontrolled we regarded as a necessary expedient. Some relaxation from the routine and the usual environment was almost a psychological requirement. The men looked forward with a good deal of pleasure to the occasions when they could eat food of their own choice. This made it more possible to keep the men contented and to extend the period of experimental observation. In this connection the introspection of Moy is pertinent. On May 21 he said: " It does seem in looking back over the experiment that we could have gotten on without the uncontrolled Sundays and the Thanksgiving recess, but these occasions were then greatly appreciated and we would have made an awful kick if they had been curtailed. You simply can not understand the matter. One's point of view is altogether different when he is in the experiment and when he is out of it".

The great increase in the oxygen consumption after the men returned to college in January is, however, of still more significance. The values for the oxygen consumption for the men in Squad A before and after the Christmas holidays have been collected and tabulated in table 135, in which it is seen that in every instance there was a very considerable increase in the oxygen consumption after the Christmas recess. The maximum increase was found with Gar of 35 c.c. per minute; the minimum was with Kon of 10 c.c. per minute.

It is also of interest to compare these increments in the oxygen-consumption level after the return from the Christmas vacation with the initial oxygen values. The latter are given in the last column of table 135. With one subject, Moy, the oxygen consumption on the return to college is actually higher than it was at the beginning of the year, being 229 c.c. after Christmas as against the initial value of 209 c.c. With Tom the difference was only 6 c.c. per minute. With all others the post-Christmas value was at least 15 c.c. less than the initial oxygen measurement. It is clear, therefore, from this table that the period of free eating during the Christmas holidays, possibly in conjunction with other factors, such as freedom from college activities and anxieties, -contributed materially towards increasing the oxygen consumption. The gaseous metabolism curves show, however, that the oxygen consumption rapidly decreased after the rise following the Christmas period.

The stimulus to the metabolic activity as a result of these periods of excess feeding was thus greatly increased. It is regrettable that a control of these subjects was not possible during this period, or, in the absence of strict dietetic control, at least an exact knowledge obtained of the total output of nitrogen in the urine.

Table 135. - Effect Of Overeating Upon The Oxygen Consumption Of Squad A