PLANT BREEDING 261 



the normal plants, it may take possession of the field and ex- 

 clude the others. When a variation in a plant makes it very 

 different from the original, it is commonly known as a sport, 

 or imitation. Thus a red-flowered form may suddenly appear 

 among plants that normally bear white or yellow flowers, 

 double flowers may spring up in the midst of single-flowered 

 specimens, or well-flavored fruits may be discovered among 

 inferior kinds. The Lucretia dewberry was derived from the 

 wild dewberry in this way, and many of our bush fruits have 

 had a similar origin. The Concord grape is another interest- 

 ing example of a sport derived from a familiar wild plant. 



Inducing variation. While one may occasionally find among 

 wild plants a desirable specimen that has arisen from seed or 

 bud variation, and transplant it to better quarters before the 

 common plants of the region have overwhelmed it, the task of 

 watching either wild or cultivated plants until such variations 

 occur is a tedious one. Fortunately for the plant breeder, it 

 has been found possible to hasten matters and to induce vari- 

 ation by manipulating the plants in various ways. Increasing 

 the food supply is one of the most efficient means of produc- 

 ing variation. It seems as if many qualities latent in the plant 

 are only brought out when food is abundant and all the other 

 conditions for growth are favorable. A change in location may 

 also cause plants to vary. When they have grown for any 

 length of time in one region, they become in a measure spe- 

 cially adapted to it and have little further need of change ; 

 removal to a different region calls for new adjustments, and 

 consequently favors variation. Farmers and gardeners often 

 send to other localities for a change of seed, and it is believed 

 that the practice of buying new seeds from the seedsmen each 

 year, instead of saving seeds from the previous crop, may 

 affect the character and variability of the new plants grown. 

 A difference in the amount of light received by the plant is 

 still another cause of variation. Pruning has a similar effect, 



