FOREWORD 



ALTHOUGH evolution, considered as a whole, constitutes 

 to-day the most firmly established of all the great scientific 

 hypotheses, it nevertheless presents some serious diffi- 

 culties in its systematisation and its philosophy. 



The principle of evolutionary theory, based as it is 

 on leading facts of the natural sciences, defies any 

 honest attempt at refutation. 



Nevertheless, there are, in the doctrine of trans- 

 formability as taught up to the present, weak points 

 and serious lacuna^ on which its enemies base their 

 hopes. No longer daring to attack it from the front, 

 they hope to turn its flank. 



It would be therefore, not only puerile, but also 

 dangerous from a philosophic point of view, to deny 

 or to dissimulate these weak points and defects. It is 

 well on the contrary to seek for their origin and their 

 explanation by placing them in full light. 



The objections to the evolutionary theory put 

 forward in this work are not, I repeat, objections to the 

 principle. They do not aim at the fact of evolution. 

 They are, however, serious because they displace the 

 two pillars on which transformability has been erected, 

 that is to say, the classical notions of ultimate cause and 

 manner of effect. 



The mechanism of evolution is now found to need 

 revision. This mechanism, as is well known, arose 

 from two great hypotheses those of Darwin and 

 Lamarck. 



The Darwinian hypothesis assigned an essential 

 function to natural selection, that is, the survival of the 

 fittest in the struggle for life; the fittest being- those 



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