THE INDIRECT JUSTIFICATION OF ENTELECHY 245 



We therefore leave the theory of oxidation and approach 

 the general subject of metabolism ; of this general subject 

 oxidation has proved to be but a part. 



" ASSIMILATION ' AND " DISSIMILATION ' 



Metabolism, i.e. the change of chemical specificities during 

 the differentiation, growth, and functioning of the organism, 

 is generally considered under the two headings of " assimi- 

 lation ' and " dissimilation." Few terms in science are 

 more ambiguous and problematic in meaning, and few 

 terms are used so freely and recklessly. Of course nobody 

 would mind if they were only used to signify that some 

 of the processes in the organism which lead to chemical 

 results proceed from the simpler to more complicated 

 chemical compounds, while the rest proceed in the opposite 

 direction. In that case one could only object that the 

 words synthetic and analytic, as commonly used by 

 chemists, would suffice for the needs of physiology also. 

 But, as a rule, something else and something more is meant 

 whenever the words " assimilation ' and " dissimilation ' 

 are used and this " something more " is extremely 

 problematic. 



We here must enter the realm of so-called physiological 

 chemistry, with which I must confess I am not at all 

 familiar ; but in spite of that I hope that the following 

 discussion, dealing with some very general and almost 

 purely logical questions exclusively, may serve to elucidate 

 a little what might be called the central point of 

 physiology. 



Whenever the words " assimilation " and " dissimilation ' 



