INTRODUCTION ix 



physico-chemical constellations capable of independent 

 existence, and capable of indefinite growth by dis- 

 sociation. They are parts of the organism, which, 

 having received the impulse of life, an impulse which 

 soon becomes exhausted, exhibit for a time some of the 

 phenomena of the organism. What Physiology did 

 attain in such investigations was an analytical descrip- 

 tion of some of the activities of the organism. It did 

 not describe life, but rather the physico-chemical 

 reactions in which life is manifested. The description, 

 it should be noted, is all-important for the human race 

 in its effort to acquire mastery over its environment ; 

 and there is no other way in which it may be carried 

 further but by the methods of physical Science. Given- 

 ness is one, though we arbitrarily divide it into the 

 domains of the organic and the inorganic, and there 

 can be only one way of describing it. That is the 

 mechanistic method. 



Nevertheless all this is only a description, and our 

 Philosophy must be the attempt to understand our 

 description. The mechanistic biologist, in the attempt 

 to identify his Philosophy with that of a former genera- 

 tion of physicists, says that he is describing a physico- 

 chemical aggregate — an assemblage of molecules of a 

 high degree of complexity — actuated by energy, and 

 undergoing transformations. But our scepticism as 

 to the validity of this conclusion is aroused by reflect- 

 ing on its origin. If it was borrowed from the Philo- 

 sophy of a past Physics, and if the more penetrating 

 analysis of the Physics of our own time has made a 

 new Philosophy desirable, should not Biology also 

 revise its understanding of its descriptions ? For 

 Biology has not stood still any more than Physics, 

 and the Physiology of our own day has become different 

 from that of the times when the mechanistic Philosophy 



