CHAPTER II 



PHYSICAL AND CHEMICAL METHODS- 

 CRITICISMS AND DIFFICULTIES 



We now come to the third class of methods: chemical and 

 physical methods. Let us listen once more to Claude 

 Bernard.^ 



*The knowledge of the definite and elementary conditions 

 of phenomena can only be attained in one way, namely by 

 experimental analysis. Analysis dissociates all the complex 

 phenomena successively into more and more simple 

 phenomena, until they are reduced if possible to just two 

 elementary conditions. Experimental science considers 

 only the definite conditions which are necessary to produce 

 a phenomenon. Physicists try to picture these conditions 

 ideally, so to speak, in mechanics and mathematical 

 physics. Chemists successively analyse complex matter, 

 and in thus reaching either elements or definite substances 

 (individual compounds or chemical species) they attain the 

 elementary or irreducible conditions of phenomena. In 

 the same way biologists should analyse complex organisms 

 and reduce the phenomena of life to conditions that cannot 

 be analysed in the present state of science. Experimental 

 physiology and medicine have no other goal.* 



All the functions of life are a remote consequence of the 

 chemical functions of the molecules which enter into the 

 constitution of each cell. Thus, one of the main problems of 

 the modern biologist is the -discovery of the relations existing 

 between the structure and the properties of the elementary 

 cellular substances, humours and tissues of a living organism, 

 and the integral phenomenon which we call Life. 



This affirmation admits an identity' between the determinism 



* Introduction a V etude de la medecine experimentalei 4th ed., 1920 

 (Delagrave), p. 113. 



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