No. 580] ORIGIN OF SINGLE CHARACTERS 



227 



or " elementary species" which is a subspecific stage 

 comparable to the ''mutation" of Waagen. 



7. De Vries's Observations on the Discontinuous and 

 Indefinite Origin of Characters 



The sudden origin of "characters," new, germinal, 

 saltatory, in every direction but of sufficient value to 

 come under the influence of selection— these are the es- 

 sential features of the famous imitation hypothesis of 

 De Vries. While I do not accept this hypothesis as a 

 demonstrated natural principle like that of Waagen, the 

 opinions of its distinguished author may be clearly set 

 forth as compared with the observations of Waagen 

 which have been repeatedly confirmed and verified: 



(1) De Vries's "mutants" differ from the "muta- 

 tions" of Waagen in appearing as fully formed "charac- 

 ters" and attracting our immediate attention and obser- 

 vation, instead of passing through a long series of initial 

 and rudimentary stages in which they arc barely dis- 

 cernible. (2) The "mutation-characters" observed by 

 De Vries differ from Waagen 's imitation-characters in 

 lacking any definite or determinate direction ; on the con- 

 trary, it is of their essence that they appear in any or 

 all directions. (3) They agree, however, with the "mu- 

 tation-characters" of Waagen and with the rectigrada- 

 tion-characters of Osborn in the fact that similar muta- 

 tions may arise independently at various times in 

 branches of the same stock, thus giving rise to homo- 

 morphic characters. (4) Let us note that the new sys- 

 tematic unit of De Vries, the "mutant" or "elementary 

 species," is a space or geographic phenomenon; it may 

 be contemporary with many other mutants of a single 

 Linnaean species. (5) The "mutation-character" of De 

 Vries is not a demonstrated equivalent to the "mutation- 

 character" of Waagen, which is a time or geologic phe- 

 nomenon character, observable only in a long series of 



Now as to the present state of evidence for the saltation 



