BIOLOGICAL INFORMATION CHEMICALLY CONVEYED 103 



than in that of its catalytic components, which latter probably are 

 a symptom rather than a cause. But there is a giant step from the 

 establishment of sequential specificity in proteins, nucleic acids, 

 polysaccharides to the formulation of the manner in which the 

 "information" stored in them is not only preserved, but also 

 transferred from one class of components to the other. The 

 polysaccharides and lipids cannot at all be fitted into what little 

 we know. As regards the nucleic acids and proteins, however, 

 it would appear to me safer, instead of postulating a hierarchy, 

 to envisage a triangular relationship, e.g., as follows: 



1 

 DNA 



/ \ 



PNA Protein 



2 3 



No arrows have been placed in this diagram, for their direction 

 may conceivably be different in different systems; so that, for 

 instance, in a plant virus the relation is between 2 and 3, in 

 bacteriophage duplication and in bacterial transformations 

 between 1 and 3, in autarkic systems between 1, 2 and 3. It is, 

 moreover, quite conceivable that the transfer of information often 

 can proceed in either direction and that the prevailing impression 

 that it invariably flows from the nucleic acids to the proteins is 

 mistaken. We may not yet have learned how to isolate suitable 

 protein preparations; I should not be surprised if it were found 

 eventually that both halves of a plant virus, the PNA and the 

 protein, may be "infective". It was, therefore, not without pur- 

 pose that I used the plural above in speaking of "life and its 

 origins". 



One could, however, ask: Is th^e cell really nothing but a system 

 of ingenious stamping presses, stencilling its way from life to 

 death? Is hfe itself only an intricate chain of templates and 

 catalysts and products? My answer to these and many similar 

 questions would be No; for I beHeve that our science has become 

 too mechanomorphic, that we talk in metaphors in order to 

 conceal our ignorance, and that there are categories in biochemis- 



References p. 108 



