, 1876-07-29

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Il i, not easy to determine how TAR
'hc notifications induced by changed
md Inherited habits OF life are due 10
mere custom, and how far to the selcc.
ton of individuals which have varied IN
u desired manner. Sporting dogs, for
example, will not touch the bones of
gamc birds, whereas most other dogs de-
your them with greedincss but this is
distinction which breeders would seek to
emphasize. The domestic hog is fond
of barley, the wild boar Ia said TO dis.
dian It, and this disdain would seem to
bc inherited, for some Wild pigs bred in
captivity showed an aversion for this
grain while Others of the same litter rel
ished it, The period of CESSATION and
maturity as well rs the season and the
act of breeding Are strongly affected by
domeslicn,ion. Thus the wild drake
pairs with one female, but his domestic
confrere is po!ygamous. Iii well known
thu. certain breeds OF fowls have lost the
habit of incubation, With plants, too,
the period OF vegetation is easil,
changed, and the deviation is inherited
"a in the case OF summer and winter
wheat. Under a new climate, annual
plants occasionally become perennial,
and some deciduous bushes become ever
green in hot countries. IL is to be noted
that such radical alterations in the phc.
nOmcna of life, whether due to habit, TO
the direct action of selection, or to so.
called spontaneous variability, would be
apt TO entail notifications Of structure.
To this category belongs the much dis
puted subject of acclimatization. by
many naturalists the attempt to acClima-
tie either animals or plants has been
pronounced chimeraa With plants
propagated from buds, at all events,
habituation to novel climatic conditions
rarely produces any effect. Thus the
Jerusalem artichoke, produced from tu-
bers, is said to be as tender in England
rs when first introduced, and this ap.
pears TO be the case with the potato,
which, until recently, was seldom multi
Piled by seed. Darwin comedies that
even with seedlings aud with animals
there will be little or no accl;matization
unless the harder individuals are either
Intentionally or uncons'iously preserved.
But as no single instance has been re.
corded either with animals or plants
"of har,lier individuals having been long
and steadily selected, though such selec-
tion is admitted to be indispensable tor
the improvement. Of any other character,
it is not surprising that man has done
little in the acrlimatization OF domesti-
Gated animals and cultivated plants.'
1t may well be, however, that under ma
tuve races and species being obliged to
shift for themselves, would become
adapted to widely different climates
through spontaneous variation regulated
by the operation Of the survival OF the
tittest."
Notifications OF structure from ar
rested development. amounting to mon.
strosities, may be passed over; but the
rudimeutary organs which, even with
species in state of nature, are extreme
ly common, claim some attention. It is
noticed that such organs are peculiarly
liable to variation, for being useless, they
are not influenced by natural selection.
When par. has become wholly super
auous, NO doubt the principle Of econo-
my Of growth comes into play, since it
would be an advantage to an organism
exposed to severe competition to save
the development OF any useless part.
Blu. as Mivart has pointed out, whore the
rudiment has been very much reduced,
the saving from its further reduction
would bs utterly insignificant, and this
maniiestly holds good if the part be
formed Of mere cellular tissue entailing
little expenditure OF nutriment. Never
theless the long-continued crossing OF
individuals furnished with an organ
which "fuctuates in greater degree
toward decrease than increase" should
slowly but steadily lead to its diminu-
tiou and ultimate disappearance. With
animals and plants reared by man, ON
the other hand, where there is NJ recur-