870 NUTRITION AND HEAT REGULATIOX. 



ing metabolism, which results finally in the oxidation of the great 

 mass of the food material and which is essential for the production 

 of body heat, and, second, the tissue metabolism proper that is, 

 the synthesis and disassimilation of the living substance itself. 

 This latter metabolism varies probably in the different tissues; 

 it is concerned with the building up and breaking down of the living 

 machinery and is attended by the absorption as well as the liberation 

 of heat, and the energy necessary for effecting these reactions is 

 obtained from the heat energy liberated by the oxidation processes. 

 In this last thought there is contained a suggestion which may 

 serve as an explanation of the fundamental value of the physiolog- 

 ical oxidations to the body. It may be supposed that these oxida- 

 tions furnish the energy necessary for the anabolic or synthetic 

 metabolism of living matter. In those organisms or cells that 

 lead an anaerobic existence that is, an existence in the absence of 

 free oxygen the energy necessary for the process is obtained per- 

 haps from hydrolytic changes alone. 



