president's address. 13 



distinguish the actual from the apparent, and true modes of 

 relatedness from false ; as we thus proceed, I hold that we are, 

 de facto, explaining living process in terms of mechanism, even if 

 in so doing we may not be saying the last word about its signifi- 

 cance. 



Dr. Haldane does himself admit that " perfectly satisfactory 

 physical explanations can, for instance, be given of the manner in 

 which contractions of the muscles and of the heart respectively 

 bring about the movements of the limbs and the circulation of 

 the blood." Again, "we can explain, on purely physical and 

 chemical principles, many isolated processes occurring in the living 

 body." But it is pointed out, with perfect justice, that, under- 

 lying these more obvious mechanisms, there lies the more subtle 

 operation of a cellular activity which does not yield to a physico- 

 chemical analysis. According to the vitalistic view, any function, 

 or any aspect of function, which is capable of being thus analysed 

 is non-vital. "If we look, howevei", at the phenomena which are 

 capable of being stated or explained in physico-chemical terms, 

 we see at once thut there is nothing in them characteristic of life." 



This is, in truth, a short and easy mode of disposing of the 

 miechanical interpretation of function ; l)ut if it be true that the 

 progress of physiology has largely consisted in the elucidation of 

 function-complexes by the recognition of elementary cell- 

 phenomena underl3ang the grosser mechanical aspect of the 

 processes, then we should appear to be justified in concluding 

 from this reasoning that it is only in the elementai'y physiological 

 activity of intracellular function that we can recognise any 

 genuine manifestation of vitality. 



I see nothing to be gained by the attempt to classify the 

 functions of an organism into those which are characteristic of 

 life and those which are not. Surely any and every process 

 carried on as a part of the life of an organism is characteristic of 

 life, whether it seem to be analysable into physico-chemical process 

 or not. 



Nor will it do to admit that explanations in terms of mechanism 

 are appropriate for certain of the operations of oi^ganism, and 



