BEGINNINGS OF LIFE 3I 



and later became self-reproducing or autocatalytic. Such 

 self -reproducing catalysts or enzymes are well known to 

 the chemistry of today. In the early seas the first autocata- 

 lytic substance would have had a very great advantage and 

 would have soon dominated the situation. In modem or- 

 ganisms, including man, the self-duplicating chromosomes 

 with their many hereditary determiners, the genes, are still 

 carrying on this autocatalytic activity. It was W. M. Stan- 

 ley in 1935 who first succeeded in crystallizing a virus, the 

 tobacco mosaic. He obtained a chemically pure nucleopro- 

 tein, which can be stored indefinitely and yet will produce 

 the tobacco mosaic disease if placed on the tobacco leaf. 

 Viruses have also been photographed by the new electronic 

 microscope. Although we know viruses now only as para- 

 sites, that does not exclude the possibility that there may be 

 free-living forms. We simply have no way at present of 

 determining them except by their effects (disease produc- 

 tion). One very remarkable characteristic of all viruses is 

 their high mutability; they undergo apparently spontaneous 

 molecular rearrangement or chemical change of some sort 

 (mutation) which alters their effects. In their mutations, 

 ultramicroscopic size, and general chemical nature, they are 

 like the genes of heredity; the similarity is most striking. 



One can assume that the first primitive cells were the re- 

 sult of the assembling of genes to form aggregates, later 

 differentiation and mutation leading to an hereditary con- 

 trol through the formation of independently existing chro- 

 mosomes. Some of today's most primitive bacteria are at this 

 stage. The addition of protoplasm and the retention of the 

 chromosome in a nuclear body would produce the first 

 complete cell, the process being controlled throughout by 

 the mutating genes. This assumption is strongly supported 

 by the study of modern bacteria and of the hereditary 

 determiners of all organisms from the most primitive to 

 man. Before the advent of the first primitive cells, nature 

 was dependent entirely on the "food material" in the me- 



