DO VARIETIES RUN OUT ? 71 



crossing from other inferior sorts it may in a short 

 time lose its acquired excellence. 



Practically, therefore, varieties, at least those 

 cultivated from seed, do run or wear out, but they 

 do not necessarily do so, but on the other hand 

 may be expected to continually improve if care is 

 taken in their cultivation and selection. The proper 

 course therefore, is not to drop the old varieties 

 entirely, and thus lose the advantage already gained, 

 but to continually improve them and use them as 

 the basis for better varieties. 



