| How much of the acclimatisation of species to any peculiar climate is due to mere habit, and how much to the natural selection of varieties having different innate constitutions, and how much to both means combined, is
obscure question. That habit or custom has some
I must believe, both from
and from the incessant advice given in agricultural works, even in the ancient Encyclopædias of China, to be very
in
animals from one district to
is not likely that man should have succeeded in selecting so many breeds and sub-breeds with constitutions specially fitted for their own
the result must, I think, be due to habit. On the other
→I can see no reason to doubt that
natural
tend to preserve those individuals which
born with constitutions best adapted to
→their native countries. In treatises on many kinds of cultivated plants, certain varieties are said to withstand certain climates better than
this is
strikingly shown in works on
published in the United States, in which certain varieties are habitually recommended for the
and others for the southern
and as most of these varieties are of recent origin, they cannot owe their constitutional differences to habit. The case of the Jerusalem artichoke, which is never propagated
→in England by
seed, and of which consequently new varieties have not been produced, has even been
→advanced —
for it is now as tender as ever it
→was — as proving that acclimatisation cannot be effected! The
also, of the kidney-bean has been often cited for a similar purpose, and with much greater weight; but until some one will sow, during a score of generations, his kidney-beans so early that a very large proportion
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