On the Origin of Species By Means of Natural Selection: Or, the Preservation of Favoured Races in the Struggle for Life — John Shaqi
On the Origin of Species By Means of Natural Selection: Or, the Preservation of Favoured Races in the Struggle for LifeDarwin, Charles
Science
On the Origin of Species By Means of Natural Selection: Or, the Preservation of Favoured Races in the Struggle for Life
Darwin, Charles
Evolution (Biology); Natural selection
excite astonishment and even laughter. The turbit has a very short and
conical beak, with a line of reversed feathers down the breast; and it
has the habit of continually expanding slightly the upper part of the
oesophagus. The Jacobin has the feathers so much reversed along the
back of the neck that they form a hood, and it has, proportionally to
its size, much elongated wing and tail feathers. The trumpeter and
laugher, as their names express, utter a very different coo from the
other breeds. The fantail has thirty or even forty tail-feathers,
instead of twelve or fourteen, the normal number in all members of the
great pigeon family; and these feathers are kept expanded, and are
carried so erect that in good birds the head and tail
touch; the oil-gland is quite aborted. Several other less distinct
breeds might have been specified.
In the skeletons of the several breeds, the development of the bones of
the face in length and breadth and curvature differs enormously. The
shape, as well as the breadth and length of the ramus of the lower jaw,
varies in a highly remarkable manner. The number of the caudal and
sacral vertebræ vary; as does the number of the ribs, together with
their relative breadth and the presence of processes. The size and
shape of the apertures in the sternum are highly variable; so is the
degree of divergence and relative size of the two arms of the furcula.
The proportional width of the gape of mouth, the proportional length of
the eyelids, of the orifice of the nostrils, of the tongue (not always
in strict correlation with the length of beak), the size of the crop
and of the upper part of the oesophagus; the development and abortion
of the oil-gland; the number of the primary wing and caudal feathers;
the relative length of wing and tail to each other and to the body; the
relative length of leg and of the feet; the number of scutellæ on the
toes, the development of skin between the toes, are all points of
structure which are variable. The period at which the perfect plumage
is acquired varies, as does the state of the down with which the
nestling birds are clothed when hatched. The shape and size of the eggs
vary. The manner of flight differs remarkably; as does in some breeds
the voice and disposition. Lastly, in certain breeds, the males and
females have come to differ to a slight degree from each other.
Altogether at least a score of pigeons might be chosen, which if shown
to an ornithologist, and he were told that they were wild birds, would
certainly, I think, be ranked by him as well-defined species. Moreover,
I do not believe that any ornithologist would place touch; the
oil-gland is quite aborted. Several other less distinct breeds might
have been specified.
the English carrier, the short-faced tumbler, the runt, the barb,
pouter, and fantail in the same genus; more especially as in each of
these breeds several truly-inherited sub-breeds, or species as he might
have called them, could be shown him.
Public-domain text, read in full here on John Shaqi.
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