ON PHYSICO-CHEMICAL METHODS AND PROBLEMS. 5 



as late as the eighteenth century great physicists such as 

 JOHANNES BERNOULLI attempted the solution of such 

 subjects as Dissertationes physico-mechanicae de motu 

 musculorum et de efjervescentia et jermentatione. 



In the first half of the nineteenth century the great 

 development of physics, more especially electricity, 

 favored the wonderful development of physical physi- 

 ology which began its career in Germany. 



But both these times physics were insufficient to exhaust 

 the problem of life, and the fully developed reaction to the 

 iatro-mechanical school finds counterpart in the reaction 

 of modern times, the participants of which are divided 

 between two camps. The belief of one of these, the 

 neovitalists, can be traced back to the "anima" of 

 GEORG ERNST STAHL. In this teaching vital force 

 which has been so often pronounced dead is born again. 

 The second group, not less dangerous than the first, 

 employs an atomic mechanics for the explanation of life 

 phenomena, and mistakes the death-dance of the mole- 

 cules for living reality. 



In this time of threatening retrogression the seeds of 

 modern physical chemistry fall upon that narrow field 

 of endeavor which we call our own. But if this new 

 and flourishing science is not also to prove a hindrance 

 to investigation by exceeding its natural limits, it is well 

 that we define first of all the boundaries within which its 

 laws hold in biological questions. 



Let us attempt first of all to get a conception of the 

 significance of the law of the conservation of energy as a 

 means of biological research. This attempt seems all 

 the more justified since OSTWALD, whose great services 

 in the development of physical chemistry demand the 



