266 Metabolie Iiifluenee of Underfeeding [Jan. 



exchange speedily reached its lowest level, having diminished by 

 fully 23 per cent, or by almost as miich as it did within the previous 

 seven weeks of underfeeding (25 per cent). The energy equivalent 

 of the respiratory exchange was only 350.4 cal. at the end of the 

 underfeeding experiment, whereas at the beginning it was 546.3 

 cal., and remained practically constant at 450 cal. during the inter- 

 vening period. The respiratory quotient during the latter part of 

 this experiment increased from 0.76 and 0.84, showing that the 

 supply of fat in the body had been exhausted and that the dog was 

 drawing on his protein. This inference is further sustained by 

 the Observation recorded in a former preliminary communication, 

 that the nitrogen elimination in the urine has actually increased at 

 the same time. 



It is generally believed that, although metabolism is reduced in 

 consequence of an insufficient supply of food, it shows no change 

 when referred to the unit of either body weight or body surface. I 

 cannot agree with this view, which is neither borne out by the facts 

 of my experiments nor is it physiologically correct in its inference. 

 By comparing the data of a number of respiration experiments, for 

 different periods, it was found that the minimum respiratory ex- 

 change undergoes first a very marked reduction with the beginning 

 of underfeeding but gradually increases again, and even exceeds the 

 normal. The smallest energy requirement of the dog, per kilo, was 

 39.3 cal., but it was 43.6 cal., or 11 per cent more, after the dog had 

 lost 42.35 per cent of its original weight. It is, however, preposter- 

 ous to juggle with mathematical fractions, kilograms or Square 

 meters, when the subject under consideration is a biological entity. 

 We are dealing in every instance with an organism, with an indi- 

 vidual, and whatever its physical condition, whether well nourished 

 or emaciated, it must be treated in its entirety. Facts disclosed by 

 a study of the basal metabolism of convalescence give more color 

 to this idea. On the basis of this conception the animal reacts to 

 underfeeding as a physiological unit, and its minimum energy re- 

 quirement, while continually diminishing, passes through three dis- 

 tinct phases : rapid decline, relative stability and, finally, renewed 

 abrupt decline. 



The essential data in this connection may be stated as f ollows : 

 The average basal metabolism of a normal dog was 546.3 cal., which 



