8 PHYSIOLOGY 



we may not finally succeed in describing vital phenomena in the " conceptual 

 shorthand " * used by the physicist, involving his ideal world of ether, atom, 

 and molecule. At present we are far from such a consummation. The 

 principle of adaptation is the only formula which will include all the pheno- 

 mena of living beings, and it is difficult to see how this principle can be 

 expressed by means of the concepts of the physicist. 



This difficulty, which must be felt with greater force the more deeply the 

 physiologist endeavours to peer into the processes within the living cells, 

 has led some, even at the present day, to the assumption of some special 

 quality in living organisms which is designated as ' vital force ' or ' vital 

 activity.' Such views are classified together under the term vitalism. 

 From his beginning man has been accustomed to draw a sharp line of dis- 

 tinction between those phenomena which by their constant occurrence seemed 

 to him natural, and therefore explicable, and those phenomena of which he 

 could not see the determining antecedent, and which were to him, therefore, 

 anomic and capricious. To the latter he set up graven images, and not 

 perceiving his own springs of action, endowed them with a self-determining 

 personality such as he imagined himself to possess. This procedure, though 

 possessing certain advantages in allowing him to perform his common duties 

 free from the ever-lurking fear of supernatural interference, suffered from 

 the great drawback that it fenced off unknown phenomena as unknowable 

 and not to be known. It has therefore acted as a continual check on the 

 growth of man's knowledge and control of his environment. Such a graven 

 image is vitalism. As a working hypothesis it must be sterile. Just as the 

 hypothesis of special creation would impede all research into the relationships 

 of animals and plants, so vitalism would stay the hand of the physiologist 

 in his endeavours to determine the changes which occur within the living 

 organism. In many cases, however, the terms ' vitalism ' and its antithesis 

 1 mechanism ' are used unjustifiably. The production of energy within 

 the body is due to the oxidation of the food-stuffs. In certain functions it is 

 not yet fully established whether the changes involved take place at the 

 expense of the energy, hydrostatic pressure or otherwise, of the fluids outside 

 the cells, or whether energy is supplied to the process by the cells themselves 

 at the expense of oxidative or other changes occurring in their living sub- 

 stance. Both views are possible, but the adoption of either by a physiologist 

 does not justify the statement that he is a 'vitalist,' ' neo-vitalist,' or 

 ' mechanist.' The office of the physiologist is the determination of the changes 

 which occur in the living body and the establishment of the causal nexus 

 (i.e. the routine of sequences) between them. For such a man to describe 

 himself as a vitalist or mechanist is as germane to the subject as if he were 

 to call himself a Trinitarian or a Plymouth Brother. 



Throughout this chapter we have assumed no necessary dividing line 



between the different classes of phenomena 'in the conceptual universe, 



although in. the present state of our knowledge we are far from being able 



to include the whole of them under the same general laws. It might be 



* Karl Pearson, "Grammar of Science," p. 328 et seq. (2nd ed.) 



