PLANT BREEDING 47 



The work is not easy, requiring an exceedingly 

 keen perception of minute differences, great 

 accuracy, and extreme care in treating the or- 

 ganisms operated upon, and even with all the 

 inherent naturally acquired variations added to 

 those secured by scientific crossing and numerous 

 other means, the careful accumulation of slight 

 individual differences through many generations 

 is imperative, after which several generations 

 are often, but not always, necessary to thor- 

 oughly "fix" the desired type for all practical 

 purposes. 



The above applies to annuals, or those plants 

 generally reproduced by seed each season. The 

 breeder of plants which can be reproduced by 

 division has great advantage, for any valuable 

 individual variation can be multiplied to any 

 extent desired without the extreme care neces- 

 sary in fixing by linear breeding the one which 

 must be reproduced by seed. But even in breed- 

 ing perennials the first deviations from the ori- 

 ginal form are often almost unappreciable to the 

 perception, but by accumulating the most minute 

 differences through many generations the devia- 

 tion from the original form is often astounding. 

 Thus, by careful and intelligent breeding any 

 valued quality may be made permanent, and 

 valid new species are at times produced by the 



