32 evolution: the ages and tomorrow 



dium; coacervates and viruses could not synthesize, they 

 could only absorb. The true organism, on the other hand, 

 can synthesize or build up its protoplasm from simpler 

 chemical configurations. These syntheses are the work of 

 enzym.es, which the true organism possesses and which are 

 absolutely necessary to its development. 



We now have a degree of certainty that genes control 

 this biosynthesis. In certain primitive forms (the red bread 

 mold, for instance), N. H. Horowitz, H. J. Teas, and M. 

 Fling have shown that the synthesis of substances needed by 

 the organism is produced in a series of successive steps, each 

 step being the specific action of a gene. Even in the human 

 being, as A. E. Garrow and others were able to show, cer- 

 tain metabolizing failures are traceable to a simple gene de- 

 fect; and many other instances are available in the literature. 



In the origin of early living forms, the power to synthesize 

 became of paramount importance. Oparin assumed that the 

 first organisms found a large supply of organic substances 

 of all kinds in the waters. There had been a long period of 

 slow energy storage in the ancient seas, probably through 

 some 500,000,000 years. At first, organisms were able to 

 find all the chemicals required for their simple needs ready 

 at hand; but a time came when the supply was exhausted. 

 In fact, we assume that today the spontaneous generation of 

 pre-life substances is not likely since present-day living 

 forms are constantly, and with exceeding thoroughness, 

 searching out and devouring any organic material. When 

 the first supply of energy substances was exhausted, most 

 of the early organisms perished, and it is at this point that 

 something like a truly "living organism" appears. 



These living organisms had learned to synthesize their 

 own building blocks and with these to construct their 

 bodies. Horowitz has given us a possible way in which this 

 was accomplished. He was able to show that in the red 

 bread mold at least seven different genetically controlled 

 enzymes are necessary for the synthesis of an amino acid, 



