IV. THE SUPREMACY OF GENES 245 



molecules, nucleic acids may cause the polymerized product of the 

 protein molecules to become rigid and strong, thereby the polymerized 

 product is endowed with the ability to behave as strong assimilase. 

 In this hardening action DNA may be more effective than RNA, since 

 it is known that RNA is split by the action of solium hydroxide, 

 whereas DNA is more stable and resists this treatment. Application 

 is made of this difference for the quantitative determination of each 

 nucleic acid in the presence of both of them ; after the destruction of 

 RNA by sodium hydrooxide, DNA is precipitated by the addition of 

 proteins in acid solution (28). Presumably organisms make use of this 

 difference and allocate DNA to genes which require the strongest 

 pattern, and RNA to cytoplasmic particles to be subjected to the genes. 



In addition, owing to its rather weaker structure RNA may 

 readily split off the energy-rich phosphate bond which may provide 

 the energy necessary for the protein synthesis as will be discussed in 

 greater detail in Chapter IX in this Part. This may be the more im- 

 portant reason why RNA is allocated to cytoplasmic particles where 

 the protein synthesis may chiefly take place. 



There appear to exist substances other than nucleic acids which 

 may be able to exert hardening effect upon protein complexes. Di- 

 valent cations, such as Ca, and polysaccharides, for instance, may be 

 regarded as such substances, but it should merit attention that only 

 nucleic acids seem to contribute the template action of viruses or 

 virus-like agents including genes. This may be ascribed to the 

 ability of nucleic acids, unlike other hardening agents, to stabilize 

 the fine, specific pattern needed for the template action. It is claimed 

 that there is as great a variety of nucleic acids as proteins (29) ; and 

 again it is emphasized that the fundamental differences between 

 groups of virus are correlated with their nucleic acid composition 

 (30), and moreover that nucleotide composition of a viral nucleic acid 

 is characteristic of the species (31). If nucleiotides are arranged ac- 

 cording to the specific pattern of the protoplasm, nucleic acids with 

 the specific composition will be produced. According to Hershey et al. 

 (32), phage DNA can be distinguished by its hydroxymethylcytosine 

 content from normal bacterial DNA, which contains cytosine, indicating 

 that bacterial pattern changed by the virus is revealed in the pattern 

 of DNA. 



The analogies between genes and viruses have been discussed by 

 numerous workers. Distinct difference between them seems to lie in 

 that viruses can proliferate indefinitely in the cell, whereas genes 

 appear to multiply only in an orderly and restricted way. However, 

 the patterns of genes like those of viruses do multiply indefinitely in 

 the cell, that is, the directing influences of the genes can spread 



