V. 



DO VARIETIES RUN OUT ? 



TATED in this way, the question must be 

 answered in the affirmative. Improved varieties 

 of fruits, grains and vegetables are being continu- 

 ally produced, yet the actual advance in quality 

 and productiveness is surprisingly slow. If every 

 new variety which has been brought into general 

 cultivation had been a permanent advance on all 

 that had been known before the standard of culti- 

 vated plants must by this time have been far 

 higher than it now is. It is impossible to doubt 

 this. If, on the other hand, we mean, as we gen- 

 erally do, by this question, that varieties necessar- 

 ily run out, without any visible cause, we are hardly 

 entitled to answer the question until we have 

 examined the possible causes of degeneration. 

 The most important cause to which this degener- 

 ation of varieties has been attributed is that of 

 propagation by grafts, buds, or division of the 

 plant in some manner, instead of by seed. Knight 

 believed that a variety propagated by grafts would 

 run out and become inferior in fruit and sickly in 

 tree at about the time the original tree reached its 



(66) 



