142 LAWS OF VARIATION'. Chap. V. 
tioTis in transposing animals from one district to an¬ 
other ; for it is not likely that man should have suc¬ 
ceeded in selecting so many breeds and sub-breeds with 
constitutions specially fitted for their own districts: the 
result must, I think, be due to habit. On the other 
hand, I can see no reason to doubt that natural selection 
will continually tend to preserve those individuals which 
are 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 others: this is very strikingly 
shown in works on fruit trees published in the United 
States, in which certain varieties are habitually recom¬ 
mended for the northern, and others for the southern 
States; 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 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 
case, 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 
are destroyed by frost, and then collect seed from the 
few survivors, with care to prevent accidental crosses, 
and then again get seed from these seedlings, with the 
same precautions, the experiment cannot be said to 
have been even tried. Nor let it be supposed that no 
differences in the constitution of seedling kidney-beans 
ever appear, for an account has been published how 
much more hardy some seedlings appeared to be than 
others. 
On the whole, I think we may conclude that habit, 
