IMPROVEMENT OF PLANTS 47 



have a new variety in which most of the plants will bear 

 several ears. This is improvement by selection. Even 

 plants such as potatoes, that do not generally produce 

 seeds, have been improved by selecting the best hills for 

 planting the next year. 



Select for one quality at a time. In improving a 

 variety, change can be made most rapidly by selecting 



FIG. 37. SOME RESULTS OF CROSSING TWO VARIETIES OF CORN OF 

 DIFFERENT COLORS 



chiefly for one thing at a time. That is, we must decide, 

 say with corn, whether we would rather increase the length 

 of ear, or the length of kernels, or the number of ears per 

 plant. We might desire all three of these qualities in our 

 new variety, but it would take many years to make the 

 desired improvement, if we chose one plant for number of 

 ears, another for length of ear, and a third for length of 

 kernel, and planted these seeds together. The better way 

 is to find some variety of corn already existing that is 



