METHODS OF ANIMAL PROPAGATION 



353 



treated, are saved and planted. When these new plants produce 

 fruit, only the best seeds are selected. Frequently, the young 

 plants are grafted upon other 

 trees to hasten the growth. Hy- 

 bridization is but the beginning 

 of breeding. Careful selection 

 must be continued, so that a pure 

 type is established. 



Methods of animal propaga- 

 tion. If a mutant with a desir- 

 able character is found, it is bred. 

 In case the new character is dom- 

 inant, it will appear in the FI 

 generation, but the animal of this 

 generation will be hybrid. This 

 hybrid is then mated with an 

 animal which shows the same 

 desired character. Sufficient 

 matings must be made to get 

 the character in a pure form. 

 This sometimes necessitates close 

 breeding. By close breeding is 

 meant mating individuals closely 

 related, as grandparent with off- 

 spring of the second, third, or 

 succeeding generations. The fact 

 that animals frequently take a number of years to mature is 

 a serious difficulty met with in animal breeding. Close breed- 

 ing does not necessarily reduce the vigor, but, if there are unde- 

 sirable characters present, they may be doubled and the offspring, 

 then, cannot be used for breeding purposes. In case the new 

 character is recessive it will not appear until the F 2 generation. 

 Then, if two individuals of different sex of this generation pos- 



The Beach plum grows in clusters. It is a 

 small plum, smaller than the American plum. 

 When these two plums are crossed, an im- 

 proved plum, much larger than either parent, 

 is produced growing in bunches like the 

 parent Beach plum. 



