538 STRUCTURE AND LIFE HISTORIES 



biological world with a new method of study. It has 

 demonstrated that the method of evolution may be studied 

 by experimentation, and this demonstration is, probably, 

 de Vries's greatest service to science. The mutation 

 theory should also be of great service to breeders. It 

 has helped to establish plant and animal breeding on a 

 more scientific basis, has pointed the way to correct 

 methods where men were formerly groping in the dark, 

 and has showed that results of commercial value do not 

 require a life time, but may be obtained within two or 

 three seasons. By the application of modern methods it 

 has been possible, within a few seasons, to obtain new 

 strains of oats yielding as much as 14 bushels per acre 

 more than the variety from which they were derived, and 

 to produce new strains of corn not only giving a larger 

 yield, but maturing nearly two weeks earlier than the 

 parent variety. 



459. Classification. — Mere information is not science. 

 A ''book of facts" is not a scientific treatise, for it is 

 composed of bits of unrelated information, presented on 

 some artificial basis of sequence, as for example, alpha- 

 betically. Scientific knowledge, in addition to being as 

 accurate as possible, is characterized by having an orderly 

 arrangement in one's mind, and this order is based on a 

 logical, fundamental relationship between the facts and 

 ideas. Only by such an arrangement of our ideas are we 

 able to understand their relation to each other, their rela- 

 tive importance, and their real significance. Classifica- 

 tion, therefore, is essential to all science. The very 

 existence and use of such words as oaks, maples, roses, 

 indicate that men have grouped or classified their ideas 

 of certain plants {e.g., red oaks, white oaks, black oaks, 



