264 Priyiciples of Plant Culture. 



tween tJie 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 

 dififer from each other as widely as possible, provided 

 only that they are capable of crossing freely. Crosses 

 between allied species (hybrids (23)), when this is pos- 

 sible, 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, whatever its quality, 

 may be crossed with any other hardy apple of first qual- 

 ity, whether it keeps poorly or well, though of two ap- 

 ples 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 variety, 

 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 de- 

 sired qualities should be chosen. 



440. Cross-Fecundation is accomplished through cross- 

 pollination of the flowers (152); i. e., by placing pollen 

 from the anthers of a flower of one of the varieties we 

 desire to cross upon the stigma of the other variety. 



441. Preparing the Flower for Crossing. To prevent 

 self-pollination (152) in perfect flowering plants (154), 

 we emasculate (e-mas'-cu-late) the flowers, i. e., remove 



