THE PLACE OF BIOLOGY. 49 



the special field of biology it enables us to unify our 

 observations, and to predict, just as the conceptions of 

 mass and energy do in another field. I have tried to 

 show you that this conception is necessary to biologists, 

 though it is also inconsistent with the physico-chemical 

 conception of the universe. The inconsistency exists 

 for the present ; but there is no reason why, with the 

 advance of both biology and the physical sciences, a 

 common meeting-ground should not be found. I, for 

 one, believe that it will be found, though I am equally 

 certain that it will never be found through attempts to 

 reduce biological phenomena to physical and chemical 

 phenomena as the latter are generally interpreted at 

 present. I am a firm believer in evolution as a scientific 

 working hypothesis ; but to me it seems that in tracing 

 the present into the past we are illuminating the past 

 just as much as the present. If we ever succeed in 

 tracing life back to what we at present regard as inorganic 

 conditions, we shall have altered radically and completely 

 our present ideas of what inorganic conditions are ; only 

 then shall we have found that meeting-ground which can 

 never be found so long as our present conceptions of the 

 inorganic world remain. 



This brings me to a further point, which I can only 

 briefly touch upon. When we analsye the conception 

 of organism we find that it includes both structure and 

 activity as the expression of organism. Organic struc- 

 ture is structure actively present ; and the element of 

 constancy in organic activity is organic structure. Even 

 from the purely physico-chemical standpoint organic 

 structure is nothing but a molecular stream. Inasmuch 

 as the conception of organism expresses observations 



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