44 LIFE AND DEATH. 



Such was the state of things during the first years 

 of the nineteenth century. It lasted, thanks to the 

 founders of contemporary physiology — Claude Bernard 

 in France, and Brlicke, Dubois-Reymond, Helmholtz, 

 and Ludvvig in Germany — until a separation took 

 place between biological research and philosophical 

 theories. This delimitation operated in physiology 

 properly so called — i.e. in a branch of the biological 

 domain in which as yet joint tenancy had been the 

 rule. An important revolution fixed the respective 

 divisions of experimental science and philosophical 

 interpretation. It was understood that the one ends 

 where the other begins, that the one follows the other, 

 that one may not cross the other's path. There is 

 between them only one doubtful region about which 

 there is dispute, and this uncertain frontier is con- 

 stantly being shifted and science daily gains what 

 philosophy loses. 



§ I. Vital Phenomena in Constituted 

 Organisms. 



A displacement of this kind had taken place at the 

 time of which we speak. It was agreed, that as far as 

 concerns the phenomena which take place in a con- 

 structed and constituted living organism, it would no 

 longer be permissible to allow to intervene in their 

 explanation forces or energies other than those 

 which are brought into play in inanimate nature. 

 Just as when explaining the working of a clock, 

 the physicist will not invoke the volition or the art 

 of the maker, or the design that he had in view, but 

 only the connection of causes and effects which he 

 has utilized ; so, for the living machine, whether the 



