34 ARON. 



ENERGY REQUIREMENT AND FOOD CONSUMPTION. 



Because the animals kept at constant weight during the experiment 

 lost energ}^ normally belonging to their bodies, we may conclude that the 

 energy given in the food was less than was required for maintenance alone. 



The energy requirement for the maintenance of a growing animal 

 is equal to that for an adult of the same size. According to the surface 

 law, we can find the amount of energy required for maintenance for dogs 

 of any weight by means of the following formula : 



3 



E = 1039Xll.3VW^ where E = energy and W = weight. 



Eubner has shown that a dog of about 6 kilos requires for maintenance 

 50 to 55 calories per kilo of body weight, a value 10 per cent below that 

 given by the above fonnula. 



In order to make the conclusion clear it will be necessary to compare 

 the energy requirements of those dogs the body weights of which remained 

 constant with the total number of calories actually given to them in their 

 food. 



The two dogs in experiment I, receiving from 80 to 8S calories, kept 

 their weight constant at from 1,800 to 1,850 grams. There can be no 

 d-oubt that these animals received considerably less than the required 

 amount of energy, which should be from 150 to 160 calories. In spite 

 of this fact they not only did not lose in weight, but even showed a 

 slight tendency to increase. However, this experiment was comparatively 

 short and we do not know how the animals would have behaved later on 

 the same food. 



In experiment III one animal, number XIV, of less than 1,000 grams, 

 received from 70 to 75 calories and increased slightly in weight. Its re- 

 quirement, according to the surface law, was from 115 to 120 calories. 

 This animal died in ninety days, probably of inanition. 



Dog XI of about 1,000 grams increased its weight slightly but con- 

 stantly, while receiving from 90 to 95 calories, the requirement being 

 from 125 to 130 calories. This animal began to lose weight, beginning 

 with about the ninetieth to the one hundredth day and continued to lose 

 when the energy intake was increased to 100 calories. 



In experiment II a dog (VI) of more than 3,250 grams body weight 

 received 140 calories, about one-half only of its requirement (250 calo- 

 ries), and within fifty days increased nearly 250 grams. As 270 calories, 

 were required for maintenance at this period, the intake was increased 

 to 150 calories; then the body weight approximately remained constant, 

 but still had a tendency to rise. In the next part of the experiment 135 

 and soon thereafter only 120 calories were given. Following this, the 

 body weight began to fall. The animal then died of inanition. 



The body weight in the last experiment remained at a standstill for 



