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THE AMEBIC AX NATURALIST [Vol. XLII 



Vries' doctrine of mutation as a substitution for the 

 Darwinian conception is, I believe, to accept a part for 

 the whole and to place before the farmer and stockman 

 a doctrine which, if generally accepted as a substitute for 

 the broad conception of Darwin, can not but be narrow- 

 ing and injurious. 



DeVriesian and Mendclian phraseology, in daily use, 

 may be to blame, but in reading many of the late exposi- 

 tions one is led to question whether the doctrine of con- 

 stancy of elementary species or constancy of unit char- 

 acters can be accepted by biologists and breeders with 

 any less damage to after progress than that which fol- 

 lowed the once complacent acceptance of the Linrcean 

 dogma of the constancy of species. 



DeVries, of course, argues for the acceptance of the 

 validity of evolution by mutations, and while one may 

 readily concur that such mutations occur, one who works 

 largely with cereal crops and lias always recognized that 

 the individual is the proper starting point for selection 

 work, is apt to be astonished in reading his new work on 

 "Plant Breeding," and falls to questioning whether 

 after all, a mutation may not be merely a "fluctuating 

 variation," big enough and stable enough to be recog- 

 nized. Is it possible that the nature of these changes is 

 different in kind or only in quantity and range of dura- 

 tion? Does accident play so large a part in plant de- 

 velopment and plant breeding as indicated by most 

 DeVriesian writers ? One need not object because of the 

 wonderful things said of elementary species, for good 

 Darwinians have always believed in the existence of 

 strains and subspecies which would admit of the name; 



