NUCLEIC ACIDS, DECODING, ETC. 165 



will know that the distinction between the AT types and the 

 GC types of DNA was first made here at Columbia, just as was 

 the introduction of such much used terms as the hypochromicity, 

 the denaturation, the heterogeneity of nucleic acids and many 

 other things. 



Now for some of the problems posed by the chemical structure 

 of a single- or double-stranded polymer as it is assumed to exist 

 in DNA; and much of what I have to say appUes also to RNA. 

 Glancing at an arbitrary segment from such a very highly poly- 

 merized macromolecule, we see that the nucleotides are linked 5' 

 to 3', that their arrangement is arrhythmic, but that the com- 

 plementariness regularities are maintained. The lowest estimate 

 of molecular weight of such a polymer is about 6-10^, except 

 for a few small viruses; the highest estimate has no limit: the 

 latest quotations on the market were around 180-10^. Even with 

 only ten thousand nucleotides per strand there are 10^^^^ isomers. 

 We deal with four or five components; but the "alphabet" is not 

 as meager as it may appear, for these few letters spell out 

 "words" that are very long indeed: ten thousand letters or more. 

 There could, therefore, be plenty of information for the unhappy 

 cryptographer. But what is impUed in such a statement as "DNA 

 is the repository of biological information"? This is, of course, 

 a very convenient slogan and may be taken as another example 

 of the motorized anthropomorphism that disfigures much of our 

 biological reasoning at present. The concept postulates the exist- 

 ence of a chain of information in the cell which is thought to be 

 represented by a series of signals, as it were, emanating from a 

 specific DNA and transmitted by a specific RNA messenger of 

 matching composition to the unspecific ribonucleoproteins of the 

 ribosomes, thus instructing the latter to proceed to the manufac- 

 ture of specific proteins. A simple-minded chemist could, of 

 course, ask himself whether this was more than a terminological 

 scaffold conceaUng our ignorance, something of the order of an 

 allegory, pretty but awfully vague. 



But there can be little doubt: sequential specificity of high 

 polymers of cellular origin is, as we have learned in the recent 



