350 THE FIRST ORGANISMS 



and the ' purposefulness ' of their internal structure. Not 

 only are the many tens and hundreds of thousands of chemi- 

 cal reactions which occur in protoplasm, and which together 

 constitute its metabolism, strictly co-ordinated with one 

 another in time, harmoniously composed into a single series 

 of processes which constantly repeat themselves, but the 

 whole series is directed towards a single goal, towards the 

 uninterrupted self-preservation and self-reproduction of the 

 living system as a whole in accordance with the conditions 

 of the surrounding medium. 



Here the term ' purposefulness ' should, of course, not be 

 taken in an idealist sense as the ' fulfilment of some higher 

 design '. The word is used to denote the appropriateness of 

 the organisation of the whole system to its self-preservation 

 and self-reproduction, and also to denote adaptation of the 

 structure of its separate parts to the most efficient and 

 co-ordinated fulfilment of those functions necessary to life 

 which these parts subserve in the system as a whole. 



The high degree of adaptation of the separate organs to 

 the carrying out of their functions and the general ' purpose- 

 fulness ' of the whole organisation are extremely evident 

 even from a superficial knowledge of higher living things. 

 They were noticed by mankind a very long time ago and 

 were expressed by the 'entelechy ' of Aristotle. The essential 

 nature of this purposefulness appeared to be mystical and 

 supernatural until Darwin gave a rational and materialistic 

 explanation of the way in which this ' purposefulness ' could 

 arise as a result of natural selection. 



However, ' purposefulness ' of structure is not confined to 

 higher beings, it extends downwards through the whole 

 world of living things, right to the bottom, to the most ele- 

 mentary forms of life. It is essential for any living body but 

 is absent from the objects of the inorganic world. The only 

 exceptions are machines, but the purposefulness of their 

 structure, their adaptation to the performance of particular 

 tasks, is determined by the creative intention of those who 

 build them. Machines cannot arise of their own accord by 

 purely physical and chemical means. It is therefore pointless 

 to seek an explanation of them in purely physical and 

 chemical terms. The origin of the organisation of protoplasm 



