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 forms 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 
work which is being so assiduously carried on to-day under 
the title of experimental morphology. 
The great names in physiology since Miller are numerous, 
and perhaps it is invidious to mention particular ones; but, 
inasmuch as Ludwig and Du Bois-Reymond have been 
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