ASPECTS OF KINETIC EVOLUTION 3 1 3 



cones we have every reason to expect that indications of them 

 would remain, either in species with such numbers or in occa- 

 sional individual variations. The facts of mutation may help 

 us to be reconciled to the probability that millipedes with five, 

 six, seven, eight or nine cones may never have existed, but they 

 do not warrant the general inference that evolution goes for- 

 ward by the origination of species sideways by mutation. 



The difficulty is not that the mutations of domesticated plants 

 and animals are not as different and as readily to be described 

 and distinguished from each other as natural species. Nor is 

 it impossible that some of the species named and described in 

 formal botanical and zoological classifications represent mutative 

 variations from narrowly segregated wild types. The differ- 

 ences are not formal or theoretical, but physiological and prac- 

 tical. The conditions under which the mutations of cultivated 

 plants and animals arise are not those under which the construc- 

 tive evolution of nature has gone forward, and the mutations are 

 deficient in the primary requirements of vigor and fertility. 



That discontinuous variations may contribute to the evolu- 

 tionary progress of species in nature is no part of the mutation 

 theory of De Vries, which definitely rejects and denies an)' grad- 

 ual evolution, any continuous change and accumulation of char- 

 acters. Species once formed by mutation are just as stationary 

 and immutable, according to De Vries, as Linnaeus said they 

 were. All the evidences of gradual evolutionary divergence of 

 organic groups accumulated by Darwin and his successors are 

 ignored in the mutation theory, because no evolutionary changes 

 were detected in the original CEnotheras which Professor De 

 Vries kept in his garden for eighteen years. 



The kinetic theory is not thus at odds with the facts of 

 science. It provides an evolution of species by a thor- 

 oughly gradual, continuous process, more broadly continu- 

 ous, indeed, than any suggested before. It recognizes that 

 new variations are prepotent, and are able to accumulate and to 

 transform the species in which they appear. Species are nor- 

 mally in motion and do not depend upon the intermittent inter- 

 ference of selection, nor upon mutation, for the development 

 of new characters. Instead of finding the motive power or 



