12 president's address. 



So far as I can see there are no more "obstacles" than there ever 

 were to a mechanical view of living process. There must always 

 be possible a " mechanical explanation " of the phenomena so long 

 as observation continues to reveal underlying mechanical arrange- 

 ments. And even Dr. Haldane does not suggest that we have 

 run up against a blank wall in the experimental investigation of 

 organism according to physical and chemical principles. He does 

 not doubt that "by the further application of these principles we 

 shall continue to extend our knowledge." And in the following 

 extrpct from a private letter of earlier date than the article under 

 consideration, he expressly disclaims the disposition to set bounds 

 to progress in the direction indicated. " I do not mean," he says 

 here, " that physico-chemical investigations will in any way cease 

 to make as much progress as before in the domain of life, for one 

 can see no limit to the progress of, say, physiological physics or 

 chemistry. Nevertheless, every year makes it clearer that with 

 all this progress we seem to get further and further from physico- 

 chemical explanations of any of the elementary phenomena of 

 biolog}', growth, development, nutrition, secretion, heredity, 

 excitability, &c." 



But when it is conceded that we do actually "make progress in 

 the domain of life " by means of physico-chemical investigation, 

 one is constrained to ask " does not the knowledge so gained, 

 just so far as it goes, amount to an actual and genuine scientific 

 explanation of the phenomena concerned " 1 



It seems to me radically wrong to assume, as Haldane appears 

 to me to do when he speaks of " getting further and further from 

 physico-chemical explanations of the elementary problems of 

 biology," that such an explanation, or, indeed, any explanation of 

 phenomena whatever, is to be conceived merely as an end-product 

 of thought, or a terminal goal of scientific investigation. The 

 explanation and interpx'etation of vital phenomena is always going 

 on. Solvitur ambulando. As we learn the physics and chemistry 

 of " living protoplasm," of those parts and substances which all 

 will admit to be in some sense the embodiment of function, as we 

 determine causes and effects of events in the way of process, and 



