132 PROPAGATION OF PLANTS. 



States, is a familiar instance of a tree being reduced to a 

 mere shrub through the influence of a poor soil and 

 other uncongenial surroundings. Under favorable con- 

 ditions this species grows to a tree thirty or forty feet 

 high, but where they are unfavorable, it is but a mere 

 shrub from two to six feet high, even when the plants 

 have reached what may be considered maturity. 



Instances of permanent changes having been effected 

 through various external causes are no doubt familiar to 

 every botanist and gardener, but the practical plant 

 grower should be on his guard, lest the sudden appear- 

 ance of some hereditary character, or direct reversion in 

 seedlings to some ancient type, mislead him into think- 

 ing that the variation observed is the result of his own 

 skill in cross-fertilization. 



All plants have a tendency to vary in different direc- 

 tions, the cultivated more than the uncultivated, while 

 every new internal element introduced, intensifies this 

 proclivity to depart from the normal type, and whenever 

 a departure has been made, it is likely to become heredi- 

 tary, consequently it is often difficult, if not wholly 

 impossible, to determine to what disturbing cause we are 

 indebted for certain results. 



BUD VARIATION. This is a prolific source of varieties 

 among plants, although by far the greater number are 

 raised from seed. When a bud on a tree or other plant 

 from some cause unknown, produces a sljoot or branch 

 differing from others on the same stock, it is attributed 

 to what is called " bud variation," and the branch or 

 shoot so produced is termed a " sport," to distinguish 

 varieties originating in this way, from those raised from 

 sed, or the direct product of sexual reproduction. These 

 sports, if removed from the parent plant and propagated 

 by division, will often remain permanent, but sometimes 

 they quickly revert to the original or parent form. In 

 propagating varieties originating from bud variations, it 



