74 AGRICULTURE 



selection. Suppose that in a field of beans you find four plants 

 bearing beans a little different from the remainder. One plant 

 bears beans that mature a day or two earlier ; the second has pods 

 a little larger than the others ; the third has better-flavored beans ; 

 the fourth has more pods than the others. Suppose you save seed 

 from these plants and keep and cultivate them in four plots. The 

 second year you again select seed, choosing from the first the earliest 

 beans, from the second the largest, from the third the best-flavored, 

 and from the fourth the one bearing most pods. If you do this 

 year after year, you will have four distinct varieties. By reason- 

 able care you can keep them distinct, thanks to the strength of the 

 law of heredity. 



Effect of Cultivation. Suppose that in each case half your seed 

 is planted on fertile, well-tilled soil and that the other half is 

 planted on poor, badly- cultivated soil. You will find that on 

 the fertile soil the improvement is great and the- variations 

 decided. On poor soil, the plants will have to use most of their 

 energies to live and grow, and have little left for improvement 

 or variation. 



Three Methods of Improvement. What you learn from this 

 experiment is what others before you learned by observation and 

 experience and applied to the improvement of plants. The three 

 chief ways in which plants are improved are by seed or bud selection, 

 by cultivation, and by crossing and hybridizing. Crossing and 

 hybrid iz ing give us new varieties and even new species. A cross 

 is a plant obtained by fertilizing one variety with pollen from a dif- 

 ferent variety, as one kind of pear with another. A hy'brid is the off- 

 spring of two plants of different kinds, as a blackberry and a 

 raspberry. 



Plant Breeders. Plant breeders, by selection and reselection 

 of seeds, grafts, and cuttings, and by crossing and hybridizing 



