of the Permanence of Varieties. 193 
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 has been called seem, on both 
sides, to have overlooked this matter. 
But, first of all, the question needs to be more specifically 
stated if any good is to come from a discussion of it. There 
are varieties and varieties. ‘hey may, some of them, disap- 
pear or deteriorate, but yet not wear out—not come to an end 
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 fashion. The question, however, is not so much 
about reversion to an ancestral 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 size or product of any 
organ, for our good, and not for the good of the plant or ani- 
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 increased liability to disease, which may practically 
annihilate the race. But then the race, like the burst boiler, 
could not be said to wear out; while if left to ordinary condi- 
tions, and allowed to degenerate back into a more natural, if 
less useful state, its hold on life would evidently be increased 
rather than diminished. 
As to natural varieties or races under normal conditions, sex- 
ually propagated, it could readily be shown that they are neither 
more nor less likely to disappear from any inherent cause than 
the species from which they originated. Whether species wear 
out, ¢.e. have their rise, culmination, and decline from any 
inherent cause, is wholly a geological and very speculative 
problem, upon which, indeed, only vague conjectures can be 
offered. ‘The matter actually under discussion concerns culti- 
vated domesticated varieties only, and, as to plants, is covered 
by two questions. 
First, will races propagated by seed, being so fixed that they 
come true to seed, and purely bred (not crossed with any other 
sort), continue so indefinitely, or well they run out in tiéme—not 
die out, perhaps, but lose their distinguishing characters? Upon 
this, all we are able to say is that we know no reason why they 
