THE PRINCIPLE OF SELECTION 35I 



which characterises living organisms, biological metabolism, 

 is understandable only on the basis of the same principles 

 which govern the origin of the ' purposefulness ' of the struc- 

 ture of higher organisms, that is to say, on the basis of the 

 interaction between the organism and the environment and 

 on the basis of the Darwinian principle of natural selection. 

 This new biological law arose during the actual process of 

 the establishment of life and later took a leading part in the 

 development of all living matter. 



But can this law be applied to any system other than the 

 living organism? As we have already seen (cf. p. 261) the 

 attempt to apply the principle of natural selection to the 

 evolution of separate molecules cannot be held to be satis- 

 factory. However, we shall adopt a different approach if 

 we try to imagine the possibility of the evolution of those 

 systems which we postulated in the previous chapter as being 

 the starting point on the road to the development of living 

 systems, that is, to the evolution of the drops of complex 

 coacervates which have the properties of open systems and 

 the network of interdependent reactions characteristic of 

 such systems. 



In the very origin of such individual multimolecular 

 formations there was already inherent the necessity for their 

 further progressive development. During the time when 

 organic material was completely merged with its environ- 

 ment, while it was dissolved in the waters of the primaeval 

 seas and oceans, its evolution could be considered as a whole. 

 However, as soon as it became concentrated at definite points, 

 in colloidal multimolecular systems, as soon as these forma- 

 tions became separated from the surrounding medium by a 

 more or less clearly defined boundary and attained a certain 

 individuality, new and more complicated conditions were at 

 once created. The later history of any individual coacervate 

 drop might differ substantially from that of another coexistent 

 system. The fate of such a drop depended not only on the 

 general conditions of the external medium, but also on the 

 specific internal organisation in space and time of the system 

 in question. The details of this organisation were peculiar 

 to the particular drop and may have been somewhat different 



