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LETTER IN ENGLISH 



Fig. 1. 



mode of synthesis of protein. Regardless of their cause, knowledge of them 

 would place severe restrictions on our theories of synthetic cellular processes. 

 In recent years a number of workers have tried to elucidate relations among 

 amino acids by examining experimentally available sequences and frequencies 

 [3]. These attempts have been thwarted by some serious difficulties. The 

 known sequences are selected by the small size and ease of purification of the 

 proteins involved. The proteins are thus often unrelated as to source or func- 

 tion. The failure, in this limited range, to find constraints should therefore not 

 be taken as the final word on the problem. 



