THE RISE OF PHYSIOLOGY 193 



the study of the chemical changes going on within the living 

 matter. 



The union of these two chief tendencies into the physico- 

 chemical aspects of physiology has established the modern 

 way of looking upon vital activities. These vital activi- 

 ties are now regarded as being, in their ultimate analysis, 

 due to physical and chemical changes taking place within the 

 living substratum. All along, this physico-chemical idea has 

 been in contest with that of a duality between the body and 

 the life that is manifested in it. The vitalists, then, have had 

 many controversies with those who make their interpretations 

 along physico-chemical lines. We will recollect that vitalism 

 in the hands of the immediate successors of Haller became 

 not only highly speculative, but highly mystical, tending to 

 obscure any close analysis of vital activity and throwing 

 explanations all back into the domain of mysticism. Johannes 

 Miiller was also a vitalist, but his vitalism was of a more 

 acceptable form. He thought of changes in the body as 

 being due to vitality — to a living force; but he did not deny 

 the possibility of the transformation of this vital energy into 

 other formiS of energy; and upon the basis of Miiller's work 

 there has been built up the modern conception that there is 

 found in the human body a particular transformation-form 

 of energy, not a mystical vital force that presides over all 

 manifestations of life. 



The advances in physiology, beginning with those of 

 William Harvey, have had immense influence not only upon 

 medicine, but upon all biology. We find now the successful 

 and happy union between physiology and morphology in the 

 w^ork which is being so assiduously carried on to-day under 

 the title of experimental morphology. 



The great names in physiology since Muller are numerous, 

 and perhaps it is invidious to mention particular ones; but, 

 inasmuch as Ludwig and Du Bois-Reymond have been 

 13 



