PRESIDENTS ADDRESS. V 



to speak with some authority on behalf of that school of biologists 

 to which the term " neo-vitalist " has been applied. 



I am the more anxious to take note of the interesting essay 

 referred to on account of the fact that in my last year's criticism 

 of the neo-vitalist position it was Dr. Haldane's exposition of that 

 position that I mainly relied upon, quoting at some length from 

 a published essay of a good many years ago. It was thus with a 

 great deal of interest that I perused the re-statement of the same 

 position in his recent article. 



A brief examination of the argument of this article may serve 

 to bring the points at issue into prominence. 



After pointing out that mechanical doctrines respecting 

 the phenomena of life became dominant during the last fifty 

 years in coincidence " not only with great advances in phj'sics 

 and chemistry, but also with the appearance of plausible 

 physical and chemical theories to explain some of the most 

 fundamental jDhysiological processes," the writer follows up "some 

 of the main lines in the development of the physico-chemical 

 movement of recent times." And he endeavours to show in the 

 case of the instances chosen —and they might be easily added to 

 — that theories which treat cell-growth and nutrition as mere 

 mechanical or chemical aggregation; or secretion, absorption, and 

 excretion as simple cases of mechanical processes of filtration, 

 osmosis, and dilFusion, completely break down when tested by 

 accurate experimental investigation. " To any physiologist," he 

 continues, " who candidly reviews the j^rogress of the last fifty 

 years it must be perfectly evident that, so far from having 

 advanced towards a physico-chemical explanation of life, we are 

 in appearance very much further from one than we were fifty years 

 ago." Thus he disposes of the first reason cited in favour of the 

 rejection of vitalism in biology, viz., that there has been steady 

 progress in the direction of explaining life in terms of physics 

 and chemistry. The second objection to the vitalist position, viz., 

 that it is without meaning as a positive hypothesis, is next passed 

 in review. " This argument in its widest sense," he says, " is 

 undoubtedly based on the metaphysical assumption that the 



