x INTRODUCTION. 



there are biologists so startled by the progress 

 made through physical methods in explaining 

 phenomena once deemed, inexplicable, save by re- 

 ference to an agency interfering with physical laws, 

 that they think they have a glorious revelation 

 before them when they account life to be nothing 

 more than a chance result of the operation of those 

 laws to which the manifestations of physical energy 

 are no doubt as subject within the body as in the 

 inorganic world. Such an attitude is natural in 

 the enthusiasm of discovering that so much is ex- 

 plained which was formerly set aside as inexplicable 

 because vital. The argument runs much in this 

 fashion : Vitality not only gave no explanation of 

 any of the operations within the body, but its 

 alleged virtues prevented the search for explanation; 

 but physical research has explained much, and we 

 may expect it to explain much more. So far well. 

 But they add that it must explain everything ; and 

 in this they go too far. I trust to show that this 

 notion, often put forward with much dogmatism and 

 with unnecessary rancour, must be set aside because 

 there are phenomena, such as morphological plan, 

 which cannot possibly be referred at any future time 

 to physical laws, but indicate spirit. 



To those working habitually with physical 

 methods, no doubt spirit seems a vague and intan- 

 gible entity because unsubject to those methods. 

 The very word spirit brings down to us from olden 



