and we are immedi- ately
made conscious of this by reflecting on the differences
in in 1859 1860 1861 1866 1869 | between 1872 |
the breeds of our domesticated animals in different
countries,—more countries,—more 1866 1869 | countries,— 1859 1860 1861 1872 |
....... 1866 1869 | more 1859 1860 1861 1872 |
especially in the less civilized
countries where there has been but little artificial
selection. ↑1 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | With cattle susceptibility to the attacks of flies is correlated with colour, as is the liability to be poisoned by certain plants; so that even colour would be thus subjected to the action of natural selection.
|
Other Other 1861 1866 1869 | Careful 1859 1860 | Some 1872 |
observers observers 1859 1860 1861 1866 1869 | observes 1872 |
are convinced that a damp climate affects the growth of the hair, and that with the hair the horns are correlated. Mountain breeds always differ from lowland breeds; and a mountainous country would probably affect the hind limbs from exercising them more, and possibly even the form of the pelvis; and then by the law of homologous variation, the front limbs and even
the head would probably be affected. The shape, also, of the pelvis might affect by pressure the shape of the head
of the young in the womb. The laborious breathing necessary in high regions
would, would, 1859 1860 1861 1866 1869 | tends, as 1872 |
we have
....... 1869 | some 1859 1860 1861 1866 | good 1872 |
reason to believe,
increase increase 1859 1860 1861 1866 1869 | to increase 1872 |
the size of the chest; and again correlation would come into play. The effects
on the whole organisation on the whole organisation 1861 1866 1869 |
OMIT 1872 |
of lessened exercise with
abundant food
is is 1861 1866 1869 |
on the whole organisation is 1872 |
probably still more important; and this, as H. von Nathusius has lately shown in his excellent Treatise, is apparently one chief cause of the great modification which the breeds of swine have undergone. Animals kept by savages in different countries often have to struggle for their own subsistence, and would be
exposed to a certain extent to natural selection,
and individuals with slightly different constitutions would succeed best under different climates;
and there is reason to believe that constitution and colour are correlated.
A good observer,
also,
states that in cattle susceptibility to the attacks of flies is correlated with colour, as is the liability to be poisoned by certain plants; so that colour
would be thus subjected to the action of natural selection. But we are far too ignorant to speculate on the relative importance of the several known and unknown laws
of variation; and I have here alluded to them
only to show that, if we are unable to account for the characteristic differences of our
domestic domestic 1859 1860 1861 1866 1869 | several domestic 1872 |
breeds, which nevertheless we
generally admit
to have arisen through ordinary generation,
we
ought not to lay too much stress on our ignorance of the precise cause of the slight analogous differences between
species. species. 1859 1860 1861 1866 1869 | true species. 1872 |
I might have adduced for this same purpose the differences between the races of man, which are so strongly marked; I may add that some little
light can apparently be thrown on the origin of
these differences, chiefly
through sexual selection of a particular kind, but without here
entering on copious
details my reasoning would appear frivolous. |
The foregoing remarks lead me to say a few words on the protest lately made by some naturalists, against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very
many structures have been created for
beauty in the eyes of beauty in the eyes of 1859 1860 1861 1866 1869 |
the sake of beauty, to delight 1872 |
man, man, 1859 1860 1861 1866 1869 | man 1872 |
or, as already discussed, for the sake of or, as already discussed, for the sake of 1869 |
or for 1859 1860 1861 |
or, as already mentioned and discussed, for the sake of 1866 |
or the Creator (but this latter point is beyond the scope of scientific discussion), or for the sake of 1872 |
mere
variety. variety. 1859 1860 1861 1866 1869 |
variety, a view already discussed. 1872 |
|