444 ANNALS NEW YORK ACADEMY OF SCIENCES 



The sting of this vehement declaration is in the underlying implication 

 that the limitation placed upon the applicability of natural selection was 

 deemed necessary because of Mr. Darwin's inability to free his mind from 

 the belief that it could not act upon large and sudden variations as well as 

 upon small and unimportant ones. This point of view seems illogical 

 when we consider his repeated declaration that no qualitative distinction 

 could be established between the two kinds of variation, but it may be par- 

 tially accounted for by the fact that a slight confusion at times existed in his 

 mind concerning the general modus operayidi of natural selection, through 

 which he attributed to it a causal power as well as a mere sifting effect. Both 

 Lyell and Wallace took him to task for this double use of the term and, there- 

 fore, in the third edition of the "Origin" he attempted to clear up this point 

 by means of this statement: 



"Several writers have misapprehended or objected to the term natural selection. 

 Some have even imagined that natural selection even induces variability, whereas 

 it implies only the preservation of such variations as arise and are beneficial to the 

 being under its conditions of life." ' 



Nevertheless, almost side by side with this explanation, we find in the 

 last edition of the "Origin" the following sentences which were allowed 

 to come down from the first edition: "Natural Selection will modify the 

 structure of the young in relation to the parent, and of the parent in relation 

 to the young." ^ "Natural Selection .... will destroy any indi\iduals de- 

 parting from the proper type." ^ If Darwin had adopted the simile of a 

 sieve, so effectively used by de Vries, he would have drawn nearer to the 

 recognition of the fact of "selection between species," even if he had not 

 been prepared to assent to de Vries's counter proposition that there is no 

 "selection tuithin the species." He might also have escaped some of his 

 apprehensions concerning the fate of adaptation, which he thought to be 

 endangered by a belief in saltation ; for the fact is that adaptedness is only 

 another name for fitness, and this is a quality inherent in the organism and 

 precedent to selection — that is to say, natural selection merely sifts out for 

 preservation the adapted or fit, allowing the unadapted or unfit to perish. 

 Now, it is impossible to see why forms both adapted and unadapted to their 

 environment may not arise through mutation and thus be offered to the 

 operation of selection. In fact Mr. Darwin has supplied us with a good 

 illustration of a case under one of these heads in a rather naive passage 

 which has run through every edition of the "Origin," to the following effect: 



1 " Origin of Species," 3d ed., 1861, p. 84, 



2 Ibid., 6th ed., 1882, p. 67. 



3 Ibid., p. 81. 



