IMPORTANCE OF THE MUTATION THEORY IN PRACTICAL 



BREEDING. 



By GEORGE HARRISON SHULL, Cold Spring Harbor, N. Y. 



The time is long past when the practical man who is looking for 

 immediate economic values is inclined to ignore the work done by the 

 devotee of pure science. Conversely, the scientist appreciates as never 

 before, the reciprocal relation existing between his work and that of 

 the man who would turn every available resource to the production of 

 something useful to man. 



Nowhere is this improved relation between the theoretical and the. 

 practical better exemplified to-day than among breeders, and 'the es- 

 tablishment of the American Breeders' Association is a noteworthy 

 indication of the existence of this improved condition. At the same 

 time this organization fosters and promotes the reciprocity that shall 

 increase the volume and the value of both scientific and economic 

 breeding. 



It is now a truism that all economic breeding must be in as great 

 degree as possible scientific, and that all scientific breeding is likely 

 to prove in the long run economic. Much of the scientific work being 

 done, seems rather remotely if at all economic, and it is not always 

 easy to indicate wherein any specific result is of practical value. Ex- 

 perience has shown, however, that all science is so closely and so com- 

 plexly interrelated, that few scientific researches are conducted, whose 

 economic bearings do not sooner or later become manifest, though 

 their true economic worth may not be recognized for years. 



While it is not fair to the scientist to insist that he shall be able 

 to point out the economic value of all of his results in the search 

 for truth he must not be so hampered it is fair to ask of science 

 that, when any of its results have a large and important bearing upon 

 economic problems, these results shall be made as available as possible 

 for the use of those who can turn them to immediate practical account. 



The mutation theory, formulated by de Vries and supported by a 

 great mass of data which he had gathered during twenty years of 

 careful and energetic work, has this large bearing. It struck a funda- 

 mental key in biological science, and is now one of the principal foci 

 about which biological research and controversy are centering. Al- 

 most daily some new scientific support for the theory is given from 



