28 



PRESIDENTS ADDRESS. 



marsupial pouch and an inflected mandibular angle, is to be 

 interpreted simply as a common family character, transmitted by 

 descent, and deriving its whole meaning from the fact of this 

 transmission ; and not as an instance of any recondite conformity 

 to an immanent ideal " type." 



Thus the supposed parallel or contrast between the progress of 

 morphology and physiology will not help the vitalist argument. 

 For in reality, morphology, just as much as physiology, has been 

 advancing by the aid of hypotheses which are conceived as eveiy 

 bit as mechanical as those which have achieved no small measure 

 of success in physiological science. 



In neither case can we affoi'd to dispense with that category of 

 explanation which alone is appropriate to the investigation of the 

 operation of an}'' material system, extended in space, and mani- 

 festing its phenomena as a series of events in time. 



A final quotation from the article under criticism will suffice to 

 summarise the question at issue. 



" All that is really shown by the partial success which has 

 attended the application of physical and chemical principles of 

 explanation in physiology is that in the course of investigation it 

 is often possible to ignore for the time the distinctive features of 

 life. For certain scientific purposes we may treat some part of 

 the body as a mechanism, witliout taking into consideration the 

 manner in which it is controlled and maintained: and in this way 

 results of great value have been attained. But in doing all this 

 we are deliberately ignoring or abstracting from all that is chai-ac- 

 teristic of life in the phenomena dealt with. The action of each 

 bodily mechanism, the composition and structure of each organ, 

 the intake and output of energy from the body, are all mutually 

 determined and connected with one another in such a way as at 

 once to distinguish a living organism from anything else. As 

 this mutual determination is the characteristic mark of what is 

 living, it cannot be ignored in the framing of fundamental working 

 hypotheses." 



With nearly the whole of this statement I am in substantial 

 agreement. For, "certain scientific purposes," I should put, "for 



