THE MUTATION THEORY OF PROFESSOR DE VR1ES. 



B3 7 Chaklp:s A. White. 



During- the sixth and seventh decades of the century just closed there 

 occurred so great a change in methods of scientific thought and prac- 

 tice among biologists that it may he properly designated as a revolution. 

 It was caused mainly by the writings of Charles Darwin, in which he 

 promulgated his theory of the evolutional origin of species by natural 

 selection. No theory pertaining to natural science ever called forth 

 more bitter and uncompromising controversy among both scientists 

 and the people at large, and none was ever more earnestly advocated. 

 Some naturalists eagerly accepted it for all, and even more than, the 

 author claimed for it; but some of the older and ablest of those students 

 of nature were then willing to accept it only as a working hypothesis. 

 Although it has necessarily always remained purely a theory, unsup- 

 ported by any practical demonstrations or experimental observations, 

 it explained so many things pertaining to the genesis of organic forms 

 as natural phenomena, and explained them so much better than had 

 ever been done before, that during the last quarter of a century the 

 Darwinian theory may be said to have had universal acceptance. Still, 

 there has not been wanting from time to time the expression of more 

 or less plausible, and even valid, objections to portions of that theory 

 on the part of sincere and able naturalists, of which all honest investi- 

 gators have taken due cognizance. 



None of the objections referred to, however, has hitherto seemed to 

 materially modify the prevailing confidence in the Darwinian theory, 

 which confidence has doubtless been increased by the powerful influence 

 which that theoiy has exerted in the adoption of evolutional methods in 

 the study of all branches of natural as well as of social science. Still, 

 a revulsion of opinion concerning all mere theories is always liable to 

 occur, and while no true naturalist will ever desire the least diminution 

 of the fame of Darwin, and none will ever abandon the fundamental 

 principles of evolution, it is not improbable that the now prevailing 

 estimation of his theory of the origin of species by natural selection 

 will eventually be modified in some important respects. In the course 

 of the year 1901 there was published in the German language the first 

 volume, in separate parts, of an exhaustive work a which is evidently 



"Die Mutationstheurie. Yersuche unci Beobachtungen iiber die Kntstehung von 

 Arten ini Pflanzenreich. Von Hugo de Vries. Leipzig, 1901. 



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