228 EXPERIMENTAL GENERAL SCIENCE 



accounts for the appearance of a large number of sports such as 

 white flowers among red-flowered plants, yellow fruits on 

 plants that normally have red ones, and an immense number of 

 other variations of this kind. If the different connecting 

 links assumed by the Darwinian Theory really did exist, we 

 should be unable to distinguish either species or genera. But 

 while it is becoming increasingly apparent that the Mutation 

 Theory will explain most of the puzzles connected with the 

 origin of animals and plants, there is still a possibility that a 

 goodly number of forms may have arisen by gradual change, as 

 suggested by the Darwinian Theory, especially in those groups 

 most closely linked together. 



194. Elementary Species. The older naturalists, while 

 admitting the origin of living things through evolution, re- 

 garded the species once formed as something fixed and unvary- 

 ing, but the Mutation Theory has shown that such species are 

 probably a composite of a number of less conspicuous forms 

 which are known as elementary species. These are what we 

 commonly call varieties. Several plants are known that 

 rather constantly produce such elementary species or "mu- 

 tants," and it is probable that other species may be made to do 

 so. When a mutant is produced that is better adapted to its 

 surroundings than the species from which it came, it may ulti- 

 mately supplant the parent form in the locality; otherwise it is 

 soon swamped by the multitudes of the ordinary form. If 

 protected from extinction by cultivation, it may prove to be 

 much superior to the original form. The different varieties of 

 apples may be regarded as elementary species. All apples 

 belong to a single species of apple, yet each possesses character- 

 istics of its own which make it easily recognized by the 

 student. 



195. Plant and Animal Breeding. Nearly all the plants 

 used by man are superior to the plants of the same species 

 found in the wild condition. In some cases our improved 



