Plant Breeding. 275 



productiveness and large fruit of the Worden, with the 

 color and delicious flavor of the Delaware. This we may 

 almost certainly acomplish if we continue our trials a 

 sufficient time. In other words, we may often combine 

 the good qualities of two varieties into a single variety 

 by securing a number of cross-fecundations between 

 the two (440), and rearing plants from the seeds thus 

 formed. 



439. The Selection of Subjects for Crossing. If 

 the object of crossing is simply to secure variation, as 

 is sometimes the case with wild fruits, the parents 

 should differ from each other as widely as posibble, 

 provided only that they are capable of crossing freely. 

 Crosses between allied species (hybrids (23)), when this 

 is possible, will be more likely to accomplish the object 

 sought than between plants of the same species. 



If the object is the improvement of present varieties, 

 the parents should be chosen with reference to the 

 qualities desired in the new variety. For example, if 

 it is desired to produce a hardy, late-keeping apple, 

 of first quality any hardy variety that keeps well, what- 

 ever its quality, may be crossed with any other hardy 

 apple of first quality, whether it keeps poorly or well, 

 though of two apples of first quality, the better keeper 

 should be chosen. 



The plant breeder should first have a definite idea of 

 the qualities he desires to secure in his proposed vari- 

 ety, and should then study with much care the qualities 

 of the varieties that he proposes to use as parents. The 

 two varieties that contain the largest number of the 

 desired qualities should be chosen. 



