September 8, 1923] 



NA TURE 



35. 



Suppose again that we shake a solution of oxygen 

 in water with zinc fihngs. Some hydrogen peroxide 

 and some zinc hydroxide are formed. Here again 

 we have an inorganic system and two coupled energy 



; transformations, (i) Oxygen + Water ^Hydrogen 



^eroxide, with increase of free energy and diminution 

 )f entropy ; (2) Zinc + Oxygen + Water — y Zinc 

 [ydroxide with decrease of free energy and increase of 

 entropy. 



Hundreds of such examples might be given. For 

 example, by a suitable coupling of voltaic cells we 

 can realise the pair of coupled transformations, (i) 

 H2 + I2 — >-2HI aq., with increase of entropy; (2) 

 2HCI aq. — >-H2 + CI2, with decrease of entropy. Thus, 

 a coupled transformation involving, when taken by 

 itself, a decrease of entropy, is no prerogative of the 

 living cell or organism. The latter is not a bit from 

 an " improbable " part of the universe, which is retard- 

 ing or reversing the operation of the second law of 

 thermodynamics in our particular part of the universe. 

 A living cell or organism does not, as it were, act 

 spontaneously. If we could photograph Mr. Home 

 in the act of " spontaneous levitation," we could 

 wager quite safely on the existence of a " coupled 

 degradation," even if we could not see it. The con- 

 tinued activity and existence of a living organism 

 depend on its utilisation of an environment which 

 is not in perfect thermodynamic equilibrium. The 

 totality of the actions involves a decrease of free 

 energy (increase of entropy), while a part will in 

 general involve a " storing of availability," i.e. an 

 increase of free energy and a decrease of entropy. 

 But this is a general characteristic of most complex 

 physico-chemical actions and reactions, including also 

 the physico-chemical actions and reactions of the living 

 organism and its environment. These facts are, of 

 course, well known. The late Prof. Benjamin Moore 

 often pointed out that the living cell acted as an 

 " energy transformer." What he really meant was 

 that it acted as a transformer of " energy potential," 

 running some energy up to a higher " potential," and 

 some down to a lower " potential," like an electrical 

 transformer. If such coupled transformations never 

 occurred in what we call the inanimate world, then 

 we might find here a real prerogative and characteristic 

 of vital activity. But the existence of such coupled 

 " up-and-down " transformations in the inorganic 

 world is the commonest of occurrences. The inorganic 

 world in its various transactions does not, in fact, 

 only " go down hill." The progress of the rake is 

 zigzag, and not wholly a piece of undiluted villainy. 



In trying to gain an understanding of the totality 

 of the actions of a living organism, it appears to the 

 reviewer that we may have to seek it in the intimate 

 NO. 2810, VOL. 112] 



actions or " behaviour " of particular individual 

 entities, rather than in the average statistical behaviour 

 of " crowds." A piece of radioactive material decays 

 according to the mathematical laws of continuous 

 change, but behind this apparent continuity there 

 lies a series of discontinuous changes or " mutations." 

 The apparently continuous activity manifested in an 

 ordinary chemical reaction, which can also be repre- 

 sented by the mathematics of continuity, is due in 

 reality to a hidden series of " critical " states and 

 " critical " transformations. Everywhere the " evolu- 

 tionary changes " of individuals appear to be of a 

 discontinuous, critical, or mutational type. Behind 

 or below the determinism of our statistical laws of 

 physico-chemical change there lies a deeper determin- 

 ism based on the transformations of particular in- 

 dividuals at particular moments. Modern physico- 

 chemical science has already obtained a large measure 

 of success in analysing this apparent " spontaneity " 

 and in discovering the intimate laws of action of 

 individuals. The City Actuary is being replaced by 

 the Harley Street physician. Meanwhile, the philo- 

 sopher with his llan of impatience (and ignorance) 

 hurls defiance at the harmless corpse of the older 

 determinism. 



Prof. Johnstone's book contains much more, however, 

 than his attempt to find a characteristic or criterion 

 of vital activity in statistical mechanics. It deals 

 with such subjects as perception, behaviour, mind, 

 memory, freewill, habit, etc., and attacks the doctrine 

 of determinism as applied to the dehberative actions 

 of animals. Thus the author says : "In most animals 

 there is some indetermination and spontaneity of 

 behaviour, and the more highly organised is the central 

 nervous system, the greater seems to be the degree of 

 indetermination that is exhibited." In much of this 

 discussion he reveals himself as a follower of Bergson. 



Finally, Prof. Johnstone, the philosopher (as dis- 

 tinct from the psychologist and biologist) allows him- 

 self the luxury of what he calls a " metaphysical 

 discussion," which, however, he relegates to an appendix. 

 We need not follow him into those " faery lands 

 forlorn." Philosophers {j,.e. the professional sort) live 

 by taking in each other's washing, and it is no part of 

 good manners to interfere with these detergent cere- 

 monies. 



The general impression which one gains from this 

 book is that the author is dissatisfied with the present- 

 day physico-chemical description of biological sequences. 

 But it does not appear that he has anything better to 

 offer. We have seen that his thermodynamical (or 

 statistical mechanical) discussion provides nothing new. 

 He brings in the modern physical theory of relativity 

 and seems to find some comfort in the reflection that 



K I 



