PRACTICAL APPLICATIONS 



243 



In the second place, since 

 all possible combinations of 

 parental characters may be 

 looked for in the F 2 genera- 

 tion, it is evident that the 

 more seeds we plant of the F t 

 generation (these seeds would, 

 of course, contain the embryos 

 of the F 2 generation) the 

 greater would be the chance 

 that all possible combinations 

 would come to expression. 



In the third place, in order 

 that the possible combinations 

 of the different parents may 

 be worked out without dis- 

 turbance, self-pollination 

 must be assured in the F 

 and succeeding generations. 



Finally, when a desired 

 combination of characters ap- 

 pears it may at once be 

 multiplied vegetatively by 

 cuttings, budding, grafting, 

 etc.; but if propagation is to 

 take place by seeds the indi- 

 vidual bearing the combina- 

 tion must be tested to see if 

 it comes true, that is, whether 

 it is homozygote for each 

 character in the combination. 

 To make this test the selected 

 individual is self-pollinated, 



FIG. 135. Illustration of all possible 

 combinations of characters appearing 

 in the offspiing of the hybrid shown 

 in Fig. 134. 



