time: the refreshing river 



none before, through the operation of the law of entropy. If we 

 return to the example given earlier of two vessels filled with gas at 

 different temperatures, and isolated from all other environment, we 

 know, of course, that with the passage of time they will come to 

 exact thermal equilibrium. When this point is reached it will certainly 

 not be possible to get any further work out of the system, but a 

 pattern has now appeared where it was not before. The system has 

 passed from asymmetry to symmetry.^ 



It is, of course, a far cry from this simplest possible case of sym- 

 metry to the extraordinarily complex patterns of symmetry produced 

 by living things, but it may be that this apparently jejune idea hides a 

 profound truth. Every stage in the thermodynamic primrose path to 

 the everlasting (but tepid) bonfire, has its own criteria of stability. 

 In the earliest stages when free energy was maximal, even the atoms 

 of the elements ^^re not stable. Later on the minerals of which the 

 earth's geography was built were stable for a long time before any 

 living protoplasm was stable. The fibrous proteins (essential for the 

 construction and maintenance of the higher forms of life^) can be 

 regarded as "degenerated" linear polymers of the globular proteins, 

 which themselves, as the work of the ultra-centrifuge school has 

 shown, are polymers of a small and relatively simple unit. Polymeri- 

 sation, too, is a notable feature of the carbohydrate group. Now 

 polymerisation is a process which goes on with a decrease of free 

 energy, just as crystallisation does, and since the most complex 

 morphological forms require the most highly polymerised substances, 

 BernaP has pointed out that this fact helps to explain for us the contra- 

 diction between thermodynamic order and biological organisation. 



From this point of view, life could be regarded as the 

 characteristic stable form of the proteins.* "Life," wrote 



^ So also — as showing the different possible definitions of order — an equalitarian 

 view might claim that when all the molecules had the same velocity the system had 

 attained greatest order. 



^ Cf. W. T. Astbury, Fundamentals of Fibre Structure (Oxford, 1933), and J. Needham, 

 Order and Life (Yale and Cambridge, 1936). 



^ J. D. Bernal, a paper to the Theoretical Biology Club, 1937. 



* Stable, of course, only in a wide sense, including within itself a vast range of 

 intermediate levels of stability. O. Meyerhof (Handbuch d. Physik, 1926, 11, 240) 

 gives an excellent description of the fundamental bases of life phenomena: "Ebenso wie 

 die Atomkerne durch Einfangen von Elektronen Eigenschaften gewinnen, die die 

 Elementarbestandteile noch nicht besitzen, die sich aber aus deren Eigenschaften herleiten , 

 so wiirden die verschiedenen Lebensausserungen — Wachstumsfahigkeit, Reizbarkeit, 

 Stoffwechsel, Regeneration, usw. — aus der hoheren Organisation der organischen, 

 Molekulen entspringen, aber diese Molekiile selbst schon Eigenschaften enthalten, aus 



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