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SCIENCE. 



[N. S. Vol. XXIV. No. 603. 



tinct varieties or species, and between pure 

 monomorphic forms, all intermediate stages 

 may exist." ^^ Even Darwin considered that 

 species, in the early stages of their history, 

 were connected ' by intermediate gradations.' ^' 

 Bicknell*" has well said, 'The current ruling, 

 more especially in vertebrate zoology, which, 

 in view of * * * intermediates reduces to 

 subspecies widely diverse organic forms, may 

 well be suspected of being artificial and of 

 attaching a fictitious importance to the mere 

 evidences of origin which chance, perhaps, 

 has allowed to remain unobliterated.' 



Farlow concludes his paper on species by a 

 sage remark : " I think we shall agree that in 

 discussing the work of botanists in other de- 

 partments than our own, it would not be wise 

 to exact a rigid conformity to our individual 

 conceptions of species, etc." It is another 

 critic of mutation who tells us*^ that ' at the 

 peripheries or borders ' of f aunal areas ' inter- 

 grades ' between species*^ occur. 



One who says that " de Vries has failed en- 

 tirely to take notice of this fundamental [ !] 

 principle," surely can not have read that " new 

 species and new varieties are seen to be quite 

 free from their ancestors, and not linked to 

 them by intermediates," *^ and that the links 

 between elementary species " often apparently 

 overlap and can only in rare cases be deter- 

 mined on the sole ground of field observa- 

 tions," but that ' pedigree-culture is the 

 method required,' etc.** Has the critic read: 

 " Transitions are wholly wanting, although 

 fallaciously apparent in some instances," as 

 they appeared to be to Merriam,*^ " owing to 

 the wide range of fluctuating variability of 



°^ Vernon, I. c, p. 41. 



^' Darwin, I. c, p. 426. 



""Torreya, 6: 94, 1906. Cf. also Science, 

 February 16, 1906, p. 257, where Cook reduces 

 three species and three varieties of Utethesia to 

 one species because of the intergradations. 



*^ Merriam, I. c, p. 256. 



^^ Or should we say 'subspecies'? 



■*' ' Species and Varieties,' p. 18. ' Elementary ' 

 species plainly from the context. 



" ' Species and Varieties,' p. 18. 



"Merriam, I. c, p. 243. 



the forms concerned, or the occurrence of 

 hybrids and subvarieties." *" 



If it is stated that de Vries " has failed 

 * * * to show that his elementary species 

 and his mutations " {other mutations, we sup- 

 pose is meant) " are not connected by inter- 

 mediate forms with each other," then we can 

 not believe the writer has read the lucid defi- 

 nition : " any form which remains constant 

 and distinct from its allies in the garden is 

 to be considered as an elementary species," " 

 and that ' their limits often apparently over- 

 lap,' but may be determined by the method of 

 pedigree-culture, though seldom ' on the sole 

 ground of field observations.' The experi- 

 mental facts were the source of the definition. 



' Such intermediate forms are (indeed) re- 

 corded by de Vries himself,' together with his 

 clear explanation of their significance. Bate- 

 son wrote over ten years ago : " We are con- 

 cerned not with the question whether or no 

 all intermediate gradations are possible or 

 have ever existed, but with the wholly differ- 

 ent question whether or no the normal form 

 has passed through all these intermediate con- 

 ditions." ** One of the greatest values of de 

 Vries's work lies in the fact that he was pres- 

 ent when the transition took place, and gives, 

 not a theory at all, but the record of a fact 

 observed again and again. 



If one is unable to see how de Vries can 

 maintain that the mutations have bred true, 

 as is stated on page 539 of ' Species and Varie- 

 ties,' he has only to repeat the experiment 

 himself to be convinced; and if it is implied, 

 as it clearly is,*° that all the mutants " were 

 throwing off, in each generation, additional 

 mutants," then the facts as recorded by de 

 Vries are ignored. That mutation, however, 

 may be a constant character,^'' just as truly as 

 the shape of a leaf that constantly varies 



*' ' Species and Varieties,' p. 249. 



" ' Species and Varieties,' p. 12. 



*" ' Materials for the Study of Variation,' p. 42. 



*" Ortmann, p. 747. 



°" During the mutation period of the species, if 

 the theory of mutation periods ( ' Species and 

 Varieties,' Lecture XIV.) shall finally become es- 

 tablished, and excepting, of course, the ' stray mu- 

 tations ' ('Species and Varieties,' pp. 704-706). 



