PLANT BREEDING AND EVOLUTION 211 



survival of the fittest; but it is not the survival of the fittest 

 individuals, but that of the fittest species^by which it guides the 

 development of the plant and animal kingdoms." 



SUMMARY 



Whether we accept the theory of Darwin or that of De Vries, it 

 will be evident to the student that the production and survival of 

 improved races of plants has proceeded along the same general lines 

 in culture and ID wild nature. Variations, either of the nature of 

 fluctuating variations or of constant mutations, are necessarily the 

 starting points for the origin of a new species or variety. Selection 

 of the best-adapted plants for a given human purpose, or to fit the 

 conditions of a given environment, are then made by man, or by 

 nature, through competition and struggle. 



The survival of the fittest, in nature, means that certain plants 

 possess characters, produced by variation, which enable them to 

 live in certain habitats in competition with their neighbors, while 

 other plants of the same species or kin are unable to do so. The 

 survival of the fittest, in culture, means that those plants live and per- 

 petuate their kind which most nearly meet the needs and desires of 

 man in different countries and regions. They are not necessarily 

 the plants best adapted to wild life in any given environment, since 

 man creates a new environment for the plants of his choice by irri- 

 gation, by fertilizers, and by cultivation. In other words, man 

 adapts the environment to the plants of his choice. 



The double roses, chrysanthemums, and peonies are not the fittest 

 plants to survive in their native habitats. They survive under cul- 

 ture because they are propagated and cultivated in an artificial 

 environment created by the horticulturist and the plant breeder. 

 Despite these discrepancies in the final results, evolution in nature 

 and plant improvement in culture are based upon the same general 

 laws of variation and heredity, and are dependent upon the same 

 general principle of selection. 



