A. Gray—Do varieties wear out, or tend to wear out? 111 
to be better, and so the old ones disappear. 
Or, finally, they may revert to an ancestral form. As Saag. 
lier generations, and the breeder has to guard against it by rigid 
selection. But the older the variety is—that is, the longer the 
Some of the new varieties supplant the old, that will not be 
ried i it wi 
Wants or fancies. 
Fy second question, and one upon which the discussion 
and there could ha y be a more trustworthy witness. 
. 
a fact,” he says, fifty years ago, “that certain varieties of 
+ Species of fruit which have been long cultivated cannot now 
made to grow in the same soils and under the same mode of 
