^ais 



aBBtpsaag gJ' A ww.wmtw. 



352 



NA TURE 



[Septemb; 



923 



immediately before the War the annual output in 

 horse power of both the light and heavy type in this 

 country was about equal, to-day the aggregate annual 

 power output of the light high-speed type is at least 

 ten times that of all other types, and in numbers 

 probably nearer twenty times." 



We welcome this book, and we congraiuhitj the 

 author upon its production and upon his distinguished 

 share in the campaign towards yet further develop- 

 ments. Those who take their stand with the outposts 

 in this campaign and endeavour thence to discern 

 what yet lies in the lap of time will share with Mr. 

 Ricardo his enthusiasm for one of the most stimulating 

 of adventures in the world of applied science. 



H. E. W. 



The Secret of Life. 



The Mechanism of Life in Relation to Modern Physical 

 Theory. By Prof. James Johnstone. Pp. xii-h248. 

 (London : Edward Arnold and Co., 1921.) 155. net. 



THE professor of oceanography in the University 

 of Liverpool is well known as an eminent 

 biologist with strong philosophical leanings and an 

 unusual knowledge of physico-chemical science. So 

 the title of this book and the name of its author lead 

 one to expect something of more than ordinary interest. 

 It may be said at once that this expectation is fully 

 justified, for Prof. Johnstone's book is uncommonly 

 stimulating and represents a real and determined effort 

 towards scientific synthesis. 



In the first eight chapters, the subjects of which 

 are the nature of animal life, the sensori-motor system, 

 the principles of energy, the sources of energy, on vital 

 production, brain and nerve, the special nervous 

 mechanisms, and the analysis of behaviour, the author 

 gives the reader an excellent and readable outline, 

 well illustrated with diagrams, of some of the funda- 

 mental aspects of physiology and the theory of energy 

 (including the second law of thermodynamics). It is 

 fairly obvious that these chapters are written for the 

 purpose of preparing the uninstructed reader to under- 

 stand what is to follow, for it is in the last three chapters, 

 on the mechanistic conception of life, the meaning of 

 perception, and the nature of life, that we come to 

 the kernel of the matter. 



In the first of these chapters the author describes 

 the mechanical system of Descartes. Having disposed 

 of Descartes, he then proceeds to demolish Jacques 

 Loeb, in other words, he finds the modem physico- 

 chemical " mechanisms of hfe " equally unsatisfying, 

 equally mechanical. But the last paragraph of this 

 chapter, like the concluding sentence of one of those 

 serial instalments of " blood and passion " that appear 

 NO. 2810, VOL. 112] 



in certain magazines, shrewdly whets our appetite: 

 "Anyhow, om ^n (if the (organism has come 



again to :■■ 11, t <,; " -'•'^hanical 



explanat: . and ih.i; . biology 



resorted to a physico-chemical explanation, which was 

 also insuliicient, sin- ■» • -f-s and chemistr)' are again 

 becoming mechan king about for the new 



conception that biology has now again to borrow from 

 physics, we have little difficulty in finding it, and it 

 would appear a~ ii it were really something new. The 

 concept is given to us in the physical notion of statistical 

 mechanics and to this we shall return presently." 



This sounds exciting, tho; not quite evident 



at first sight why statistical mtcliunics should be any 

 better than mechanics. However, the secret comes 

 out in the last chapter, whi'h treats of "The Nature 

 of Life." Here the author deals in a ver>' interesting 

 way with the laws of thermodynamics, his discussion 

 being based on the statistical methods of Boltzmann 

 and Smoluchowsky. It is pointed out that the universe 

 " becomes a cyclic order, such that the most probable 

 phases are those in which entropy tends towards its 

 maximum value, and the least probable ones are those 

 in which the entropy tends towards its minimum value. 

 As such it is a permanent universe, self sufficient, 

 without beginning and without end." 



Proceeding from this basis, the author arrives at 

 the following result. In inorganic processes and 

 tendencies available cncrcry runs down and entropy 

 increases ; whereas in '" vital " processes and tendencies 

 available energy accumulates and entropy decreases. 

 Summing up, he states that " In living processes the 

 increase of entropy is retarded. This is our ' vital 

 concept '." His exact meaning will be rendered clearer 

 by the following quotation. Discussing '^^-^ T.Kr,to- 

 synthetic action of the green leaf, he sa} rch 



accumulates in the green leaf exposed to sunlight, 

 but the whole system is the green leaf + t^^f fn. and 

 HgO + the 'degrading' sunlight. In the iius 



defined entropy increases very slowly. The system is 

 one in which there are coupled energy transformations, 

 (i) the degrading sunlight ; and (2) the photosynthetic 

 process. If there were no coupling, the solar energy 

 would degrade, with a maximum entropy increase ; 

 if there is a coupling the entropy increase becomes 

 minimal. The coupling is always the mark of life 

 activity." 



Suppose we illuminate some oxygen at room tempera- 

 ture with the right sort of ultraviolet light. Some 

 ozone is formed. In this inorganic system we have 



two coupled energ)- transformations, (i) Oxygen >- 



Ozone, with increase of free energ}' and diminution 

 of entropy ; (2) " degrading " ultraviolet hght, with 

 diminution of free energ%- and increase of entropy. 



