662 EVENING DISCOURSE. 



the passage of inorganic anions, though water and oxygen can pass freely in and 

 out. Between the red cells and the external blood plasma in which they are submerged 

 there exists a whole series of delicate exchange equilibria, such as water or osmotic 

 equilibrium, ion-distribution equilibria, etc. The entrance of oxygen, which combines 

 with the haemoglobin, converts it into a stronger acid and ejects carbonic acid from 

 the bicarbonate ions within the cell. Any disturbance of one of these equilibria 

 produces compensating changes in the others. The whole series of equilibria can be 

 written down in a set of precise mathematical equations. Thus two of the moat 

 important elementary phenomena of many forms of life, namely, respiration and the 

 exchanges of the red blood cells, have been analysed, subjected to exact measurement 

 and described by exact mathematical equations. The laws of physics and chemistry 

 have agair. been found to hold good. The beautiful story of this blood equilibrium 

 we owe to the labour of many distinguished physiologists, but chiefly to Lawrence 

 Henderson and van Slyke in America and to A. V. Hill and Barcroft in England. 

 That is the second example I wished to mention. These two will suffice for my 

 present purpose. What is the lesson to be drawn from them ? No less than that 

 the elementary phenomena of life are deterministic, that is to say, that events compen- 

 sate or succeed each other just as in the physico-chemical world of inanimate things, 

 and that their compensations and successions can be exactly measured and expressed 

 in the form of precise mathematical equations. Determinism exists just as much 

 or, if you please, just as little, in the elementary phenomena of the living as in those 

 of the non-living systems familiar to physics and chemistry. Claude Bernard main- 

 tained that this was so. To the imperishable lustre of his name be it said that fifty 

 years of exact research have borne witness to the truth of his faith. Do not mis- 

 understand me here. True science should have no dogmas. It would have been 

 a wonderful and a fine thing if recent research in general physiology had led to a 

 non-deterministic sequence of phenomena in the elementary condition of life. During 

 the last fifteen years theoretical physics, which has been undergoing a period of 

 unexampled and daring advance, has dropped many a hint of the existence of 

 apparently non-deterministic systems. The audacious springs of the electron within 

 the atom from one energy level to another have often appeared to be ruled by con- 

 siderations of relative probability rather than by any exact determinism in the 

 ordinary sense of this word. But we cannot as yet be sure of anything in modern 

 theoretical physics. Just as we now hear little of the jumping frog of Calaveras 

 County, so modern wave mechanics has overwhelmed the discontinuously jumping 

 electron, and seems to offer more promise of determinism than did that uneasy ghost. 

 Thus determinism in the rigorous sense of the term is no infallible dogma of science. 

 It would not be surprising if it did not exist in the minute phenomena of the world, 

 since the apparent determinism of events on a greater scale is often only the result 

 of a very high degree of statistical probability. Be that as it may, the investigations 

 of general physiology, so far pursued, indicate that the elementary phenomena of 

 life are quite as fully deterministic as phenomena on a corresponding scale of magnitude 

 in the inanimate physico-chemical world. 



Let us now make the daring supposition that general physiology, following 

 the lead of Claude Bernard, has eventually succeeded in quantitatively analysing 

 every side and ever}' aspect of the elementary condition of life. Would such a 

 supposedly complete and quantitative analysis give us a synthesis of life ? That 

 is one of the most fundamental and difficult questions of biological science. A 

 living being is a dynamically organised individual, all the parts of which work 

 harmoniously together for the well-being of the whole organism. The whole appears 

 to us as something essentially greater than the sum total of its parts. This aspect 

 of the living individual was fully recognised by Claude Bernard. It has been 

 emphasised recently by General Smxits in his remarkable book on Holism and 

 Evolution. Life, as seen by General Smuts, is constantly engaged in developing 

 wholes, that is to say, organised individualities. We may indeed learn how the 

 regulative and integrating action of the nervous system, so beautifully and thoroughly 

 investigated by that great physiologist, Sir Charles Sherrington, serves to organise 

 and unite together in a harmonious whole the varied activities of a complex multi- 

 cellular animal. We may learn, too, how those chemical substances, the hormones, 

 discovered by Bayliss and Starling, are secreted by the ductless glands and, circulating 

 in the milieu interieur of an animal, act as powerful means for harmoniously regulating 

 and controlling the growth and other activities of the various organs and tissues. 

 Nevertheless, in spite of these great discoveries, the harmonious and dynamic correla- 



