PREVIOUS INVESTIGATIONS. 27 



dog on the last days of fasting, and has computed a value which shows 

 he considers that if the animal weighed 20 kg., it would have a mini- 

 mum caloric production of 822.8 calories. We believe that Grafe 

 (like Benedict and Carpenter^ of this Laboratory) has fallen into the 

 error of using fasting values as distinguished from post-absorptive 

 values for his basis of comparison. Benedict and Carpenter have 

 discussed in considerable detail the error in using true fasting days 

 for this purpose, since unquestionably the fast has, per se, a specific 

 influence upon metabolism.^ On this ground the basal value employed 

 by Grafe is altogether too low; according to our computation, the total 

 heat production of the dog would much more closely represent 1,200 

 calories per day during the period of heavy feeding. Since during this 

 time Grafe states that 2,580 net calories per day were available, the 

 excess would correspond to about 40,000 calories, ^. e., 2,580—1,200 

 X 29 = 40,020. 



In the period of 11 days, when feeding with 1,660 calories per day, 

 the maintenance requirement would, in all probability, be not less than 

 1,112 calories, as found by Grafe. Since this is a nuchtern value, dur- 

 ing the feeding period it would unquestionably be somewhat higher, 

 leaving the net surplus smaller. Disregarding this point, the net sur- 

 plus is 548 calories, or a total for 1 1 days of 6,028 calories. In the next 

 period of 19 days, the food was hardly above maintenance. Using the 

 actual values obtained on those days when respiration experiments 

 were made and the animal was without food in the stomach, the basal 

 value can be assumed to be 1,030 calories. Since the daily energy in- 

 take during this period was 1,120 net calories, the surplus energy above 

 maintenance would be only 90 calories daily, with a total excess for the 

 19 days of 1,710 calories. At the end of this period, therefore, we have 

 a deficiency of 17,404 calories in the first 21 days to be made up, and 

 available for this replenishment 56,758 calories. On this basis one can 

 assume that 39,354 calories were stored in the body. On the basis of 

 9.5 calories per gram of fat this would correspond to approximately 

 4,143 grams or 4 kg. of fat. 



We believe, however, that Grafe has made a fundamental error in 

 assuming that the heat output of his dog outside the respiration cham- 

 ber was the same as in the respiration chamber, since his own reports 

 show that the respiration experiments were made at 22° C., while a 

 very large part of the time the dog was in the cellar with a temperature 

 of 15° C., and probably during the night with even a lower tempera- 

 ture. While exact quantitative data regarding the influence upon 

 metabolism of temperature is still too scanty for most accurate compu- 

 tations, it has been the custom of physiologists for many years to use 



' Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 261, 1918, p. 72. 



* Grafe had good precedent for using the fasting value for a base line as in similar comparisons. 



Johansson, Landergren, Sond6n, and Tigerstedt (Skand. Arch. f. Physiol., 1897, 7, p. 



29) had previously used values obtained with a man during a fast of 5 days. 



