EVOLUTION WITHOUT MUTATION.^ 



C. B. DAVENPORT. 



Professor de Vries having found in nature races that seem to 

 have arisen suddenly, fully formed, and having repeatedly 

 observed mutating individuals that breed true, declares, in his 

 " Mutationstheorie," for the universality of mutation as the 

 method of phylogenetic differentiation. He says (1901, p. 139): 

 a gradual origin of elementary species is not yet known but very 

 many cases are known in which species have suddenly made their 

 appearance. "Nach der Mutationstheorie sind die Arten nicht 

 durch allmahlige, wahrend Jahrhunderte oder Jahrtausende 

 fortgesetzte Selection entstanden sondern stufenweise, durch 

 plotzliche, wenn auch ganz kleine Umwandlungen." 



The mutation theory as a sufficient theory of evolution has 

 many supporters. Bateson has long urged a theory of this sort 

 as a result of his studies, particularly on the data collected in his 

 "Materials for the Study of Variation," 1894. In his recent book 

 "Evolution and Adaptation" Morgan adopts de Vries' views. 



Now it seems to be a common characteristic of men of science 

 when they have discovered a real and large truth to insist on its 

 universality. But, particularly in biology, this tendency is 

 fraught with danger on account of the complexity of the phenom- 

 ena involved. I am quite convinced (and have, indeed, for more 

 than a decade in my university lectures contended) that mutation 

 or sporting plays an important part in evolution. I yield to no 

 one in admiration for the work of the genial author of "Die 

 Mutationstheorie," a work that has placed experimental evolution 

 on a solid basis as a science and which has thus rendered a service 

 to biology with which Darwin's only compares. Yet, I think, the 

 acceptance of mutation as a method of evolution should not pre- 

 vent us from conceding the force of any evidence that selection of 



'Read before National Academy of Sciences, Chicago, November, 1903. 



