LIFE, CARBON'S OUTSTANDING PROPERTY 85 



structures of much greater size than any self-regenerating 

 enzyme or filterable virus, and it seems more likely that 

 the first cells came after the self-regenerating enzymes. 



It is quite possible to form an idea about the development 

 of cells from self-regenerating enzymes. As modern re- 

 search chemists have found, the behavior of enzymes and 

 particularly the crystallizable viruses is readily modified by 

 variation of the conditions; for instance, by subjecting them 

 to moderate heat. (Temperature high enough to boil water 

 destroys all enzymes.) One may assume that certain types 

 of the earliest self-regenerating enzymes were modified in 

 such a manner that the product of their action was not only 

 the enzyme itself but also some other non-enzymatic or in- 

 active material. This material may have surrounded the 

 enzyme, thereby protecting it from various deleterious 

 influences. 



A substance like starch may have been one of these pro- 

 tecting materials. The formation of a primitive cell from 

 starch thus formed is not surprising since we have seen that 

 ordinary starch forms crystals resembling cells (Figure 

 19a). In the subsequent development, more and more of 

 this material may have been formed, thus leading to the 

 development of more and more involved organisms. 



In the center of living cells proper, numerous molecules 

 of enzymes are found, mostly in the so-called nucleus, as 

 "genes." Each cell contains millions of enzyme molecules, 

 all imbedded in the protecting inactive material around 

 them. Many million cells, in turn, are needed to make up 

 an animal or plant. On account of the incompleteness of 

 our knowledge, we can only visualize the development of 

 the present existing plants or animals in a hazy outline. 



It should be clear, however, that the mere putting to- 

 gether of millions of molecules of self-regenerating enzymes 

 does not make a cell. We might just as well say that a pile 

 of apples makes an apple tree. Nor would the putting to- 



