151 



therefore is independent of environment, its direction is not 

 governed by circumstances."* Or, in "Species and Varieties" 

 (p. 696), " the ordinary external conditions do not necessarily 

 have an influence on specific evolution." 



If the statement (p. 322) that, "The evolution is in the 

 species, the power of deflection in the environment," by contrast 

 with the quotation on the same page from de Vries that " By this 

 means natural selection " (said, in the same paragraph, to be 

 "not a force of nature, no direct cause of improvement") "is 

 the one directing cause of the broad lines of evolution," is meant 

 to point out a difference in the two theories, the close propinquity 

 of the two sentences seems quite unfortunate. 



Possibly, also, the statement that, according to de Vries, new 

 characters, in order to be preserved, must be environmentally 

 useful (p. 281), would not have been written if notice had been 

 taken of de Vries's declaration that, " Harmless or even slightly 

 useless ones (mutations) have been seen to maintain themselves 

 in the field during the seventeen years of my research . . . ." 

 And on page 281, the cart and horse are surely reversed, when 

 it is stated that, according to de Vries, " new species have to be 

 made, in order to originate and preserve new characters." 



If evolution, " represents the working of no special .... 

 mechanism" (p. 323), it is difficult to understand how "The 

 final and ultimate explanation of evolution must await an under- 

 standing of the constitution of living matter" (p. 323), or what 

 the positions of "granules derived from a given ancestor" have 

 to do with evolution. We cannot escape mechanisms by writing 

 atoms and molecules, or granules, instead of chromosomes. 



De Vries is said (p. 362) to " especially insist " on the tenet that 

 the idea of species is " founded on identity of form and structure," 

 and is quoted six lines below as saying that "purely uniform 

 species seem to be relatively rare." If the term species is used in 

 each of these cases with the same meaning, the discrepancy between 

 the interpretation and the quotation is quite evident, and even 

 more so when we recall de Vries's statements in " Species and 

 Varieties," that, in species, "All sorts of variability occur, and no 

 individual or small group of specimens can really be considered 



* De Vries, Hugo. Science, II. 15 : 727. 1902. 



