172 



TILLERS OF THE GROUND 



CHAP. 



scale that it can be supplied to many people. 

 One great advantage of such plants as the lilies is 

 that once a desirable kind has been produced, it 

 may be increased by means of its bulbs, instead of 



FIG. 39. One of the improved prickly pears with large fruits pro- 

 duced by Mr. Burbank. The plant is four years old, eight feet 

 high, and bears over 400 pounds of fruit. Half of one leaf 

 put in the ground in April produced over sixty leaves by the 

 middle of September. 



only by seed. This is a great advantage, because 

 improved plants which can only be reproduced by 

 seed show a great tendency to " run back " to the 

 original stock. On the other hand, when they 

 can be reproduced by a part of the original stock, 

 such as a bulb, a cutting, a tuber, as in the 



