July 20, 1906.] 



SCIENCE. 



(fluctuating variation), is clearly brought out 

 by the author of the mutation theory. And 

 if, in speaking of ' de Vries's contention that 

 mutations are species,' one has in mind the 

 units of the systematist, then it must be in- 

 sisted that such is not de Vries's contention 

 at all, nor can such a statement be wrested 

 from the book, ' Species and Varieties,' if the 

 context is always considered. 



" However, if de Vries had claimed that 

 species might be made out of mutations, noth- 

 ing could be objected to this view." '"'^ Exactly ! 

 Then why the dissenting critique? Read, on 

 page 13 of ' Species and Varieties,' the fol- 

 lowing : 



Linnaeus himself knew, that in some cases all 

 subdivisions of a species are of equal rank, to- 

 gether constituting the group called species. No 

 one of them outraiiks the others; it is not a 

 species with varieties, but a group consisting only 

 of varieties. A closer inquiry into the cases 

 treated in this manner by the great master of 

 systematic science, shows that here his varieties 

 were exactly what we now call elementary species. 



And this on page 558 : " The first law ^of 

 mutation] is, that new elementary species 

 appear suddenly, without intermediate steps." 



Finally (page 459), "Hence we have dis- 

 tinguished between elementary species and 

 varieties proper. The first are combined 

 INTO species " (of the systematist), etc. Could 

 a clearer statement be conceived? 



There is, indeed, a sense in which this is 

 ' no new idea,' " but the recognition of it, and 

 of its bearing upon theories of descent seems 

 to be not only new, but difficult at the present 

 day of being clearly recognized and under- 

 stood. De Vries does not claim the credit of 

 originating the idea. He proposes to found 

 his theory, in part, upon " a critical survey of 

 the facts of agricultural and horticultural 

 breeding, as they have accumulated since the 

 time of Darwin.'"' 



Says our critic : " The breeding of domestic 

 races has always ( ! !) been regarded as a proc- 

 ess analogous to the one in nature by which 

 new species are produced." When, we may be 



^^ Ortmann, p. 747. 



°^ Ortmann, I. c, p. 747. 



^ ' Species and Varieties,' p. 9. 



allowed to ask, previous to the appearance of 

 the ' Origin,' had such an idea been seriously 

 or at all generally held. If we have not access 

 to the original, we may even learn from ' Spe- 

 cies and Varieties,' if we read carefully, that 

 Linnaeus looked upon species as the result of 

 special creation."* 



The failure to take some of his statements 

 at their face value, or at least to distinguish 

 clearly when he is recording a fact and when 

 he is elaborating a theory, is a peculiar feature 

 of the criticisms of de Vries, as in the present 

 critique, where it is stated that he ' finally 

 obtained more or less pure strains.' °° An 

 equally peculiar and persistent feature of 

 these criticisms is the insistence with which 

 the author's carefully defined terms, represent- 

 ing equally careful and long-needed distinc- 

 tions, are entirely ignored, thus giving to his 

 statements a wholly different color than they 

 possess in the original. E. g., " Before he 

 [de Vries] began this process of selecting and 

 segregating, the mutations were by no means 

 species, but only varieties." Where, from 

 cover to cover, of ' Species and Varieties,' is 

 any other claim made? The point is that the 

 author very carefully states what kind of 

 varieties they are, and applies to this kind the 

 term ' elementary-species.' 



Thus again, in the next sentence, " de Vries 

 further maintains that it is the mutations 

 and not the variations, that give rise to new 

 species, and he thinks [sic] that there is a 

 fundamental difference between them." A clear 

 conception of the mutation theory would have 

 resulted in some such changes as the follow- 

 ing in that sentence : " de Vries further gives 

 experimental evidence that it is the muta- 

 tions, and not the other types of variation, 

 that give rise to new species, and hetiueen 

 these kinds of variation there is a fundamental 

 difference." The critic might have added 

 here, also, the statement, ' but this no new 

 idea,' and might have quoted from Bateson: 



The existence of discontinuity in variation is, 

 therefore, a final proof that the accepted hypothesis 

 is inadequate. If the evidence went no further 

 than this the result would be of use, though 



" ' Species and Varieties,' p. 34. 



^^ Ortmann, I. c, p. 747. Italics mine. 



