210 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



we do not call the sum of our facts a real proof of vitalism, 

 it is only because we feel unable to formulate the analysis 

 of what happens in such a manner as to make a machine 

 as the basis of all reactions absolutely unimaginable and 

 unthinkable. There might be a true machine in the organism 

 producing immunity with all its adaptations. We cannot 

 disprove such a doctrine by demonstrating that it would 

 lead to a real absurdity, as we did in our analysis of 

 differentiation of form ; there is only a very high degree 

 of improbability in our present case. But an indirect 

 proof must reduce to absurdity all the possibilities except 

 one, in order to be a proof. 



Mechanistic explanations in all branches of functional 

 physiology proper, so much in vogue twenty years ago, can 

 indeed be said to have failed all along the line : the only 

 advantage they have brought to science is the clearer 

 statement of problems to which we are now accustomed. 

 But we are not fully entitled to say l that there never will 

 be any mechanistic explanation of physiological functions 

 in the future. It may seem as improbable as anything 

 can be ; but we wish to know not what is improbable but 

 what is not possible. 



Now of course you might answer me that after we have 

 indeed shown that the production of form, as occurring on 

 the basis of harmonious-equipotential systems, is a fact that 

 proves vitalism, the acts taking place on the basis of that 

 form after its production would have been proved to be 

 vitalistic also, or at least to be in some connection with 

 vitalistic phenomena. Certainly they would, and I myself 



1 Here again I should like to except from this statement the discoveries 

 of Pawlow. See page 204, note 1. 



