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THE AMERICAN NATURALIST [You XLIII 



Huxley, with his tendency to reach conclusions quickly, 

 which, he confesses, sometimes led him into mistakes, 

 saw intuitively, let us say, that the beginning of varietal 

 differences might be by a sudden leap. While Darwin, 

 who reached conclusions only after careful examination 

 of all possible contributing data, although realizing that 

 the origin of species from variations, by natural selection 

 had not been proved, thought that they furnished the 

 most favorable material for natural selection to work 

 upon. At the same time, I think that I have shown by 

 means of numerous quotations from the ' ' Origin of 

 Species" that the very slight changes which DeVries has 

 shown to mark the beginning of some varieties, while 

 recognized by Darwin, were thought of by him as of the 

 same order as ordinary (now called fluctuating) varia- 

 tions. This view is justified, I think, by his frequent 

 use of the word step. Possibly this explains why Huxley 

 found the book such a hard one to understand thoroughly. 

 It also throws some light on the unsatisfactory condition 

 in which Darwin is supposed to have left the question 

 of the origin of varieties. To my mind, instead of this 

 being a blemish on Darwin's work, as it seems to be held 

 by some recent writers, it is, when the state of biological 

 knowledge in his day is taken into account, in harmony 

 with his known caution and sagacity. To blame him for 

 not making a sharp distinction between fluctuating 

 varieties and mutations would be like finding fault with 

 Copernicus for not knowing what Kepler and Newton 

 discovered, or criticizing Newton harshly because his 

 theory of light left much for subsequent workers before 

 the electro-magnetic theory was possible. 



