Plant Breeding. 267 



444. The Selection of Crossed Seedlings is a most im- 

 portant operation in producing new varieties by crossing. 

 If none of the seedlings of the first generation exhibit 

 the desired qualities, those of a succeeding generation 

 may exhibit them. The plants nearest the ideal should 

 be selected, and all the seeds from these preserved for 

 planting. When the ideal plant is found, it may be 

 readily fixed by means of cuttings or grafts in plants 

 generally propagated in this way. In those propagated 

 by seed, several generations of culture and selection may 

 be necessary before the progeny will uniformly resemble 

 the parent. 



FIG. 175. Diagram illustrating the selection of seedlings from a cross. 



The variations in the seedlings from two crossed vari- 

 eties, and the kind of selection needed to fix the desired 

 variation, are illustrated by the following diagram (Fig. 

 175). Let a represent the seeds from two crossed flowers 

 A and B. The plants from these seeds will probably be 

 quite variable, as is indicated by the divergent lines. 

 Let us suppose the variation marked i to be nearest the 

 ideal form. The plants grown from i will again be quite 

 variable in the second generation &, but probably less so 

 than in the first generation. No plants of the second 

 generation may be nearer the ideal type than those of 

 the first generation, but we select the plant nearest to our 

 ideal, and plant the seeds from this. Each succeeding 

 generation may be expected to produce less of variability 



