HORTICULTURE AND PLANT IMPROVEMENT 13 



better adapted to the rigors or the shorter seasons of these 

 northern localities. 



22. Life forms not fixed. In many other ways plants are 

 varying constantly. It must ever be borne in mind that the 

 forms of life are not fixed, that all forms are to a certain 

 degree plastic, and that within certain limits they can be 

 changed by the efforts of skilled manipulators. The improve- 

 ment of plants is one of the great and interesting problems 

 of horticulture. 



23. Modern conditions demand the best. A merchant 

 must have on his shelves an up-to-date stock if he is to com- 

 pete on successful terms with progressive rivals. A railroad 

 company must look to the condition of its engines and cars 

 and buildings. The horticulturist is also a business man, and 

 his stock in trade is the plants he cultivates. He will take 

 risks, as does every other business man. He will have disease 

 to combat, and insect pests to control, irrigation ques- 

 tions to solve, and problems of every sort to face. Com- 

 petition has always been keen, and is keen today. It 

 is essential, therefore, that his stock be up-to-date, that 

 his trees and plants represent the best that can possibly be 

 secured. 



24. The goal. The possibilities of plant improvement 

 are so great that no matter how much has been accomplished 

 or how much may yet be undertaken, the goal will always be 

 ahead. There is plenty of room for achievement. Plant 

 improvement is of vast importance to the human race. To 

 the individual horticulturist and the scientist, it opens an 

 inspiring field for his endeavor. 



The elements in practical plant-breeding are these: (1) to 

 produce or discover a desirable variation; (2) to stabilize 

 and perhaps to improve the variation by continued selection. 

 The operator should understand the laws of heredity, that 

 he may know what is possible of accomplishment and thereby 

 direct his effort intelligently. 



