44 GENERAL PHYSIOLOGY 



contents, certain chemical transformations take place differently 

 from their customary manner in mass. 



Another consideration, which renders the assumption of a spe- 

 cial vital force still more untenable, is the following. The 

 calorimetric researches of the present time show that in the adult 

 animal which is in complete metabolic equilibrium, i.e., which 

 gives off from its body as excretions exactly as many atoms as it 

 takes in as food, complete dynamic equilibrium also exists, i.e., 

 exactly the same quantity of energy that enters the body with the 

 food as chemical tension leaves the body during the vital activity 

 of the animal. Hence all the energy that is transformed by the 

 body in the performance of its work must be derived solely from 

 the energy that comes in with the food. If this were not so, we 

 would be led to absurd conclusions ; for, if the activities of the 

 body were supplied from a fund of special energy, a " vital force," 

 we would be obliged to assume, not only that the latter is con- 

 tinually constructed in the body out of nothing in order continually 

 to maintain the work of the body, but also that the potential of 

 the food being superfluous is continually disappearing in the body. 

 At the present day no true man of science can agree with such an 

 idea. Johannes Mliller was a vitalist, and, although the law of 

 the conservation of energy was unknown to him, he felt and 

 endeavoured to avoid this difficulty by assuming that vital force 

 works according to chemico-physical laws. By such an assumption 

 a specific force, different from chemico-physical forces, is in 

 principle laid aside, for vital force is then only a collective term 

 for the complicated chemico-physical relations upon which vital 

 phenomena depend. In fact, many scientists conceive the term 

 in this sense only, and, if Mtiller had been acquainted with the 

 law of the conservation of energy, he would surely have avoided 

 the expression " vital force." 



Since the middle of the present century the old conception ot 

 vital force has disappeared completely from physiology. Hence it 

 appears strange to hear at the present time here and there 

 the catch-words of that doctrine. A careful examination of this 

 reappearance shows, however, that the old words are now employed 

 in a very unfortunate connection, that their sense has been com- 

 pletely changed, and that, when " vitalism " and " neovitalism " 

 are now spoken of, something wholly different from the old doctrine 

 of vital force is meant. In general, among the phenomena of the 

 newer vitalism two groups may be distinguished, which may be 

 termed mechanical and psychical vitalism. 1 



Mechanical vitalism is the view that vital phenomena depend at 



bottom upon the agency of physical and chemical forces ; but that 



in living organisms these forces are linked together into such a 



peculiar and thus far unexplored complex that for the present it 



1 Cf. Verworn ('96, 2). 



