XIV 



MAKING NEW PLANTS 



177 



a slow process. Mr. Burbank spent twenty-six 

 years over his lily experiments a very long time ! 

 The reason was that after he had crossed his lilies 

 he had to wait till they flowered before he could see 

 the result, and lilies grown from seed do not flower 

 for some years. Once they got to flowering size 

 he did not need to sow seed again, for he could use 

 the little bulbs, but 

 he had to wait a 

 long time till they 

 did flower. 



All this simply 

 means that when 

 plants are annuals 

 and are multiplied 

 by seed, they can 

 be improved com- 

 paratively quickly, 

 but the improve- 

 ments are not always constant the process of 

 selection has to be kept up. When plants are 

 reproduced vegetatively, and are perennials, it takes 

 longer to improve them, but the improvements are 

 more constant. 



In the improvement of fruit trees, which often 

 only grow very slowly to maturity, the process of 

 grafting has played a great part. Grafting is 

 certainly old, but it is now carried on on an 



N 



FIG. 41. How Grafting is effected. 



