86 life's beginning on the eaeth 



gether of millions of cells ever create an animal. Every 

 living thing has developed as a distinct entity; it needs all 

 its own diversified material for maintenance, not only the 

 enzymes, but countless other materials which protect or 

 hold together or facilitate communication in the entire 

 organism. The understanding of the mode of action of 

 all these other components is even more difficult than a 

 thorough understanding of the action of enzymes. 



Many details of our explanations of the origin of life re- 

 main obscure, yet we feel that we have made a step forward 

 in our understanding of life. Its amazing variability and 

 diversity now appears less enigmatic. We realize that there 

 cannot be one single self-regenerating enzyme but hundreds 

 or perhaps thousands of them, each giving rise to a peculiar 

 type of chemical change. Some of these are capable of 

 initiating an evolution of living plants and others that of 

 animals. In this manner we are led to understand the great 

 diversity of the living world. 



There is also no reason to assume that the formation of 

 the self -regenerating enzyme is limited to the earliest periods 

 of the earth. Some of them may have formed only a rela- 

 tively short time ago — a few thousand years, or even a few 

 hundred. Such an assumption would explain the simul- 

 taneous existence of highly developed and primitive animals 

 (or plants) as we actually see them on our earth. On this 

 suggestive theory, man may derive from the earliest self- 

 regenerating enzyme, perhaps a billion years ago; whereas 

 primitive organisms like bacteria arise from comparatively 

 recent formations. Of course the possibility also remains 

 that some primitive forms of life have persisted over 

 a long period of time without undergoing any evolu- 

 tionary development . 



s 



