THE 



AMERICAN NATURALIST 



Vol. XL May, 1906 No. 473 



APPLICATION OF DE VRIES'S MUTATION rilKOin' 

 TO THE MOLLUSCA 



FRANK COLLINS BAKER 



Probably no work since the publication of Darwin's Origin 

 of Species has produced such a profound sensation in the biological 

 world as the work entitled Die Mutationstheorie, by Hugo de Vries. 

 A perusal of that work (or, perhaps better for those not having the 

 time, the shorter work Species and Varieties; their Origin hif 

 Mutation) leads the zoologist to ponder upon the ([ucstion as to 

 how far these theories may be used in connection with animal 

 forms, especially with the invertebrates. Much expcrinicntarion. 

 covering a long period of time, must be done, however, before 

 anything definite can be accomplished. De Vries spent twenty 

 years raising and studying primroses. The zoologist must do 

 likewise and study some common forms for a long period, breeding 

 them under conditions conforming as closely as possible to the 

 natural environments of the organisms. The question of ele- 

 mentary species and varieties is one which would seem to have a 

 meaning in botany somewhat different from the use of the same 

 terms in zoology, in fact, in some of the Invertebrata (the Mollusca, 

 for example) there would seem to be no distinction between an 

 elementary species and a variety, the terms being synonymous. 

 However this may be, it would seem that to the Mollusca the 

 de Vries theory might be applied with some intercstini: result^. 

 The writer would ask the question: Are not many of tlic varia- 

 tions of the Mollusca produced in the manner ouilined by tln> 

 new aspect of evolution? The writer does not feel warranted 



