THE NEW PHYSIOLOGY. 73 



thought or in deed, it simply disappears from our mental 

 vision. A living organism made up of matter and energy 

 is like matter and energy made up of pure time and space : 

 it conveys to us no meaning which we can make use of 

 in interpreting the facts. 



But is there not matter and energy in a living organ- 

 ism ? Do we not assume this at every step in physiology? 

 We make use of the ideas of matter and energy in biology, 

 just as the physicist makes use of the idea of extension 

 in the investigation of matter. To the biologist, however, 

 the structure and activity of an organism are no mere 

 physical structure and activity, but manifestations of 

 life, just as to the physicist the extension of matter is 

 no mere mathematical extension, but a manifestation 

 of the properties of matter, with a physical and not a 

 mere mathematical meaning. This is the answer to 

 those who point to the dependence of physiology on 

 physics and chemistry, and conclude from this that 

 physiology cannot be anything but a department of 

 physics and chemistry. By a similar chain of reasoning 

 physics would be nothing but a branch of mathematics, 

 and mathematics itself would melt away into that 

 universe of unconnected " impressions ' which David 

 Hume imagined, but Immanuel Kant showed to be non- 

 existent. 



The limits of time prevent my giving further examples 

 of the light which the conception of the normal throws 

 on the details of every part of physiology, and I must 

 now try to probe more deeply. It may be pointed out 

 that although it is useful in matters of detail to bear in 

 mind that a living organism tends to maintain a normal 

 of both structure and activity, and to pass through a 



