GO life's beginning on the earth 



of life, for, the entire animal world feeds on plant mate- 

 rial, either directly or indirectly. The bodies of all animals 

 and men are thus built up from the various carbon com- 

 pounds which are indirectly or directly derived from the 

 plants; and the plants take them from the air. 



However, not all of this material goes to build animals. 

 A considerable portion burns up in their bodies ; it burns in 

 a slow protracted "tireless" combustion quite different from 

 the burning in red hot flame. The term "burning of food 

 in the body" is used merely because the end products are 

 the same as those of a flame. Carbon is again combined 

 with oxygen and transformed into the gaseous carbon di- 

 oxide which is exhaled by the lungs. It is then distributed 

 in the air, blown around by the wind until it hits upon green 

 leaves in the sunshine, where it is transformed again into 

 plant substance, which is eaten and "burned." The cycle 

 of carbon is thus completed. 



How does the flameless and slow combustion of food in 

 the animal body operate? Here, as in the case of the trans- 

 formation of the gaseous carbon dioxide of the air into 

 plant materials, the process can be set into operation only 

 by the activating enzymes. However, the process is not 

 so simple; the food is not all simply burned up directly as in 

 a flame since, simultaneously with this combustion, there 

 occurs the above-mentioned process of transformation of 

 food material into the substance of which the body consists. 



One feature stands out clearly if we review the endless 

 chain of transformation of matter in life and its swing back 

 and forth from plant to animal: it is the presence of those 

 powerfully activating ferments or enzymes which keep the 

 transformation going. We may consider it as a great pro- 

 gressive step that we know of the existence of these en- 

 zymes. Moreover, our research chemists have extracted 

 some of them from plants or animals and prepared them in 

 pure form. But, we are not in a. position to make real 



