546 METABOLISM 



This is called the method of indirect calorimetry, and it has been clearly 

 established by numerous observations that the results agree exactly with 

 those secured by the method of direct calorimetry described above. For 

 most purposes the indirect method is quite satisfactory, and it is espe- 

 cially valuable in cases in which there are considerable and sudden 

 changes in body temperature. That the results by the two methods should 

 agree shows clearly that the law of the conservation of energy must apply 

 in the animal body, for it is evident that if any energy were derived from 

 outside the body other than that taken with the food, the results by the 

 direct method would be higher than those by the indirect. 



