THE PLACE OF BIOLOGY, 29 



ground of physical and chemical observation into the 

 unknown ground within the living substance we are 

 investigating. The very presupposition of physiology 

 as a science is the assumption that life is a physical 

 and chemical process ; and for this reason it is justifiable 

 to speak of the " mechanism " of life, even though we 

 are not yet in a position to understand this mechanism. 



Now, it seems to me that this reasoning is radically 

 fallacious ; and I shall try to point out the source 

 of fallacy as clearly and shortly as I can. First of all, 

 I wish to emphasise a fact which few biologists seem to 

 realise — namely, that our present interpretation of the 

 inorganic world in terms of such conceptions as mass, 

 movement, atoms, energy, and even space and time 

 themselves, is only an interpretation or working hypo- 

 thesis. It has been arrived at gradually and laboriously 

 in the course of human history ; but we have no reason 

 to suppose that it is a final interpretation, though for 

 the present we cannot dispense with it, and though we 

 can be certain that any truer and deeper interpretations 

 of the physical universe must cover the facts which 

 our present interpretation covers, just as Lavoisier's 

 conception of chemical change covered all the facts 

 interpreted by StahPs phlogiston theory, to which such 

 able investigators as Priestley and Cavendish held 

 throughout. As a matter of fact, we are living in a time 

 when the ablest mathematicians, physicists and chemists 

 clearly perceive the limitations of the interpretations 

 in which they were brought up, and are striving after 

 deeper and truer interpretations. 



To those biologists, therefore, who argue that all the 

 facts which biological investigation reveals are, and can 



