268 ORIGIN OF STRUCTURES AND FUNCTIONS 



combine with definite parts of the polynucleotide chain 

 during the process of the synthesis of proteins, the participa- 

 tion of a large number (up to 64) of specific enzymes was 

 required. He is now inclined to deny the necessity for such 

 far-reaching enzymic specificity. ^^'^ 



Unfortunately there is, as yet, very little direct factual 

 evidence on this problem upon which to base a definite con- 

 clusion. One should not forget, however, that in all cases 

 where the biosynthesis of any substance has been studied in 

 enough detail, it has been shown to be based on a chain of 

 strictly co-ordinated enzymic reactions. Moreover, the simple 

 consideration of the magnitude of the free energy of the 

 peptide bonds between different amino acid residues and 

 the energy of activation needed for the formation of these 

 bonds shows that the incorporation of different amino acid 

 residues in polypeptide chains must take place at different 

 rates. Thus the kinetic conditions, which are fundamentally 

 regulated by enzymes, must play an essential part in the 

 synthesis of proteins. 



Thus, while giving due weight to the importance, for 

 the synthesis of proteins, of spatial factors in the organisation 

 of protoplasm, one must not forget about its organisation in 

 time, the conjunctions of kinetic circumstances which deter- 

 mine a particular type of metabolism. In this connection 

 a very important place is occupied by the catalytic (enzymic) 

 systems. 



The significance of spatial localisation in all vital processes 

 and, in particular, in biosynthesis was recognised by the 

 biologist R. Altmann"* as long ago as 1886. In his book 

 Studien iiber die Zelle he very perspicaciously put forward 

 the idea that the synthetic processes do not occur diffusely 

 throughout the protoplasm but are associated with definite 

 structures in it, which he called ' granules '. This idea of the 

 localisation of the synthetic processes in formed elements of 

 the protoplasm was maintained by G. Lewitsky^*^ who worked 

 on plant preparations, by A. Guilliermond^^" on the basis 

 of his observations on mitochondria, and later by E. W. 

 MacBride and H. R. Hewer,^^^ E. S. Horning^" and many 

 other authors. 



Since then more and more facts have been collected which 



