REMARKS ON FUNCTIONS 71 



reviewed recently. I shall list here only briefly what to me ap- 

 pears most significant. 



(a) The nucleic acids are ubiquitous and presumably indis- 

 pensable constituents of living matter. Autarkic entities (cells 

 and cell communities) appear to require the presence of both 

 types of nucleic acid, parasitic entities (viruses, phages) the 

 presence of one. It must be considered as highly important that 

 the transfer of biological information can be effected, or aided, 

 either by pentose nucleic acids (plant and, probably, animal 

 viruses) or by deoxypentose nucleic acids (bacteriophages). 

 Against the argument of omnipresence the objection could be 

 raised that this hardly distinguishes the nucleic acids from other 

 plastic components of living matter, e.g., the proteins or the 

 Upids, though it is doubtful whether the latter are required by 

 parasites. 



(b) The most direct evidence of an involvement of poly- 

 nucleotides of the deoxy series in the genetic apparatus of the 

 cell is due to the epochal work of Avery and his colleagues on 

 the phenomena of bacterial transformation. There can be little 

 doubt that our present understanding of the mechanisms that are 

 brought into play during transformation is at a most rudimentary 

 stage, but even less doubt that this discovery will be marked as 

 an important date in the history of biology. 



(c) The investigation of the mutagenic action spectrum of 

 ultraviolet radiation has yielded curves that closely resemble the 

 absorption spectrum of nucleic acids. Certain chemicals known 

 to react with nucleic acids exhibit mutagenic effects^^ and others 

 known to be cytostatic or cytotoxic have been shown to be in- 

 corporated into nucleic acids^^. 



(d) Boivin and his colleagues, pointed out that the deoxy- 

 pentose nucleic acid content of a diploid nucleus is constant for 

 a given species and twice the amount found in the corresponding 

 haploid nucleus^i. 



(e) Many lines of evidence suggest a role of pentose nucleic 

 acids in protein synthesis and in morphogenesis^. The relation- 

 ship has, however, remained purely formal and generic; no cor- 



References p. 75 



