Enzymic Reactions in Stationary Open Systems 453 



of Le Chatelier's principle. It only holds good within definite limits of alteration 

 of the external conditions ; (5) it must be noted that continual exchange of sub- 

 stances with the external medium is necessary for the very existence of an open 

 system. 



It is easy to see that all these new laws apply to any living organism, because 

 they are common to all open systems. Thus, in the course of evolution, catalysed, 

 chemical, open systems may be regarded as a necessary stage in the prebiological 

 period of development, preparing in advance, as it were, some of the properties 

 of the Hving organism, although these chemical open systems still did not have 

 the full ability to reproduce themselves. 



At this Symposium we have heard a ntmiber of papers describing the gradual 

 increase in complexity of substances during the history of the Earth, starting 

 with the simplest organic substances and going on to proteins, nucleic acids 

 and nucleopro teins. Three sessions of the Symposium have been devoted to 

 this. Unfortimately the other side of the problem, namely the formation and 

 development of the open systems, within the framework of which complicated 

 macromolecules were assembled and functioned, has received far less ventilation 

 in the Symposium. None the less, in our view, life could not have developed on 

 the basis of isolated macromolecules of whatever degree of complexity. Only 

 the emergence of organized exchange of substances within an open system con- 

 structed on the basis of complicated macromolecules of protein, rucleoprotein 

 and other complexes could have led to the reproduction of such a system and 

 thus to the origin of life [5]. This stage is decisive for the problem of the origin 

 of Hfe in that, from that time, the evolution of metabolism in forms of life which 

 were growing more compUcated had already begun. 



In what circimistances did there occur the formation of open systems of 

 integrated chemical reactions with the elaboration of the macromolecules and 

 molecular structures entering into their composition ? Two circumstances must 

 be noted here. In the first place, the elaboration of macromolecules facilitated 

 coacervation and the spatial demarcation from the surrounding medium which 

 is a prerequisite for the existence of open systems. Secondly, we notice a close 

 connection between structures and processes in an open system. Of course, a 

 change in structure or, even more, the introduction of new, compHcated macro- 

 molecules, could produce a sharp alteration in the processes of exchange, i.e. 

 the whole distribution of the kinetic parameters in the system. It has now been 

 established that the structures of nucleoproteins and, in particular, of the deoxy- 

 ribonucleic acids of chromosomes, viruses, etc., is of great importance in the 

 handing on of hereditary traits, though all these structures can function only in 

 particular living organisms, i.e. within a framework determined by pre-existing 

 open systems. In normal processes of inheritance, the reproduction of these 

 structures, although its mechanism is not yet clear, takes place simultaneously 

 with the reproduction of the system as a whole. When it remains in existence 

 for a long time such a system cannot be anything other than an open system. 

 From this point of view, study of the properties of catalysed open systems, 

 along with a study of the complicated, specific, molecular structures associated 

 with them, is absolutely necessary for the elucidation of the conditions under 



