I. Introduction. 



It is a well recognized fact that the science of phys- 

 iology, and in fact all biological science, has not attain- 

 ed to that degree of exactness which is characteristic of 

 the sciences of physics and chemistry. To the question, 

 how may physiology be made a more exact science, there are 

 as many answers as there are methods of investigation: but 

 there is one line of attack, based upon simple logic and 

 upon the analogous development of those sciences which are 

 nearer the goal, which may rightly claim special attention. 



Ke who surveys the development of the sciences of phys- 

 ics and chemistry, and especially the rapid advances of 

 recent years, must be struck with one phase of this devel- 

 opment. With the formation of the atomic theory, both sci- 

 ences were able to make a great advance. They were now in 

 possession of a unit by means of which they could conceive 

 of the occurrence of phenomena, explain them, and make 

 conjectures and even predictions. And with the subsequent 

 intensive study of this unit of matter, the advances in 

 physics and chemistry were marvelously accelerated, and 

 their progress was roughly parallel to the progress in the 

 study of the atom. Deprived of the conception and knowlege 

 of the atom, modern chemistry and modern physics could 



(2) 



