THE NEW PHYSIOLOGY. 59 



impression. But in the domain of natural science we 

 have to examine arguments somewhat closely, and it 

 seems to me that his admissions, which are right and 

 unavoidable, carry him so far that his defence of the 

 mechanistic theory of life is wholly unconvincing. One 

 cannot get round the fact that the mechanistic theory 

 has not been a success in the past, and shows no sign 

 of being a success in the future. 



When we look broadly at biological phenomena, it is 

 evident that they are distinguished by one universal 

 characteristic. The structure, activity and life-history 

 of an organism tend unmistakably to maintain a 

 normal. Accident may destroy an organism, or even 

 a whole species, but within limits of external environ- 

 ment which are the wider the more highly developed 

 the organism is, the normal life-history of each indi- 

 vidual is fulfilled. 



If, now, we consider the advance of physiological 

 knowledge from the standpoint of the efforts which have 

 been made, not to ascertain the causes of vital activity, 

 but to track out its normal details, the past history of 

 physiology takes on a new aspect. It becomes a record, 

 not of disheartening repulse before a hopeless wire 

 entanglement, but of continuous progress. The new 

 physiology of which I wish to speak to-night is a physio- 

 logy which deliberately and consciously pursues this 

 line of progress, leaving on one side what one may call 

 the " causal " physiology handed down to us from the 

 last generation. This new physiology is in one sense 

 not new, but very old. It is only new in the sense of 

 consciously pursuing an aim which has nearly always 

 been instinctively pursued by physiologists, and par- 



