110 <A. Gray—Do varieties wear out, or tend to wear out? 
to prove that varieties were bound to die out in the course of 
time. But if the case were fully re-argued now, it is by no 
means certain that the nays would win it. The most they 
could expect would be the Scotch verdict, “not proven.” An 
this not because much, if any, additional evidence of the actual 
wearing out of any variety as turned up since, but because a 
presumption has been raised under which the evidence would 
take a bias the other way. ‘There is now in the minds of scien- 
tific men some reason to expect that certain varieties would 
die out in the long run, and this might have an important 
influence upon the interpretation of the facts that would be 
brought forward. Curiously enough, however, the recent dis- 
cussions to which our attention Ae been called seem, on both 
sides, to have overlooked this matter. 
But, first of all, the question needs to be more spe 
stated if any good is to come from a discussion of it. The 
are varieties and varieties. They may, some of them, diss 
pear or deteriorate, but yet not wear out— not come to an en 
from any inherent cause. One might even say, the younger 
they are the less the chance of survival unless well cared for. 
They may be smothered out by the adverse force of superior 
numbers; they are even more likely to be bred out of exist 
ence by ‘unprevented cross-fertilization, or to disappear from 
mere change of fashi e question, however, is not so muc 
about reversion to a reuea, state, or the falling off of a high- 
bred stock into an inferior condition. Of such cases it is enough 
to say that, when a variety or strain, of animal or vegetable, 
is led up to unusual fecundity or of size or product of any 
organ, for our good, and not for the good of the plant or alr 
mal itself, it can be Kept so only by high feeding and excep 
tional care; and that with high feeding and artificial appliances” 
come vastly ee ee to disease, which may practi 
annihilate the race. But then the race, like the bursted boiler, 
could not be aid to wear out, while if left to ordinary condi- 
neage and allowed to degenerate back into a more natural, 1 
seful state, its hold on life contd evidently be increased 
rather “hat diminished. 
u 
more nor less eh oe to disappear from oye cause than 
i 
by two questions, 
