28 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



the figure obtained by Rubner, which imphes an increase in metabo- 

 lism of approximately 3 per cent per degree centigrade.^ We thus have 

 a probable increase in metabolism of this animal on the days outside the 

 respiration chamber of not far from 21 per cent or, roughly speaking, 

 one-fifth. With a basal daily requirement of 1,200 calories, this would 

 correspond to 240 calories per day. The four periods when excess 

 food was given numbered 66 days, of which 12 were in the chamber. 

 With an increase in the metabolism of 240 calories per day, there would 

 be a total increase in the metaboUsm of 240 X 54 = 12,960 calories, or 

 one-third of the excess computed by the above method. The excess 

 calories, which amounted to 39,334 — 12,960 = 26,374, if stored as fat, 

 would correspond to about 3 kg. of fat or 15 per cent of the body-weight 

 of the dog. It should be stated, however, that in a recent investiga- 

 tion by Zuntz^ a series of experiments carried out with a dog at a tem- 

 perature of 30° to 32° C. showed 44.4 calories per kilogram per 24 hours 

 and another series at 15° to 16° C. showed 50.2 calories. This differ- 

 ence corresponds more nearly to 1 per cent per degree than to Rub- 

 ner's figure of 3 per cent used in the above calculations.^ 



Since in our judgment the figures used in our recalculations for the 

 basal metabolism and the estimates of probable energy requirements 

 during repose are minimum rather than maximum, we believe that the 

 experiment of Grafe does not positively prove the main point of his 

 discussion, namely, that the dog, when given excess food, produced a 

 sufficiently excess metabolism to counterbalance it. 



A striking factor of Grafe's experiment must not be lost sight of in 

 that throughout the entire period of realimentation there was a very 

 great storage of nitrogen in the body. This storage, unaccompanied 

 by a marked increase in metabolism, is, we believe, fully in conformity 

 with the experience found by A. Mtiller^ with man, in which 210 grams 

 of nitrogen were stored without appreciable increase in the heat pro- 

 duction per kilogram of body-weight. Although personal conversa- 

 tion with Dr. Grafe gives no clue as to the probability of an increased 

 activity on the part of the dog when outside the chamber, it would 

 appear as if the estimates for the energy requirement on the days when 

 the animal was not in the chamber are too low. If this is the case and 

 if correction is made for the erroneous basal value obtained after a 

 period of prolonged inanition, we believe that the figures would not 

 positively prove Grafe's main contention. The addition of a large 

 amount of protein and certainly of some fat can hardly be accounted 



^ Rubner, Die Gesetze des Energieverbrauchs bei der Ernabrung, Leipsic, 1902. Hdri (Biochem. 

 Zeitschr., 1914, 66, p. 2) has pointed out that in many of Rubner'a experiments the 

 percentage difference per degree is 3 to 5 per cent. 



2 Zuntz, Biochem. Zeitschr., 1913, 55, p. 341. 



3 This difference is at least in part explained by the fact that 32° C. is considerably above the 



so-called critical temperature for most dogs. 

 * A. Miiller, Zentralbl. f. d. ges. Physiol, u. Pathol, d. Stoffw., 1911, N. F., 6, p. 617. See also 

 p. 29 of this monograph. 



