M Database Inspector (cheetah)
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|01 - Variations Under Domestication||01-03 - correlation of Growth||20||
Professor Wyman has recently communicated to me a good illustration of this fact; on asking some farmers in Virginia how it was that all their pigs were black, they informed him that the pigs ate the paint-root (Lachnanthes), which coloured their bones pink, and which caused the hoofs of all but the black varieties to drop off; and one of the "crackers" (i.e. Virginia squatters) added,
"we select the black members of a litter for raising, as they alone have a good chance of living."
Hairless dogs have imperfect teeth; long-haired and coarse-haired animals are apt to have, as is asserted, long or many horns;
pigeons with feathered feet have skin between their outer toes; pigeons with short beaks have small feet, and those with long beaks large feet.
Hence if man goes on selecting, and thus augmenting, any peculiarity, he will almost certainly modify unintentionally other parts of the structure, owing to the mysterious laws of correlation.
|01 - Variations Under Domestication||01-07 - Origin of Domestic Varieties from one or more Species||70||
It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species; but by crossing we can only get forms in some degree intermediate between their parents; and if we account for our several domestic races by this process, we must admit the former existence of the most extreme forms, as the Italian greyhound, bloodhound, bulldog, &c., in the wild state.
Moreover, the possibility of making distinct races by crossing has been greatly exaggerated. Many cases are on record, showing that a race may be modified by occasional crosses, if aided by the careful selection of the individuals which present the desired character; but to obtain a race intermediate between two quite distinct races, would be very difficult. Sir J. Sebright expressly experimented with this object and failed.
The offspring from the first cross between two pure breeds is tolerably and sometimes (as I have found with pigeons) quite uniform in character, and everything seems simple enough; but when these mongrels are crossed one with another for several generations, hardly two of them are alike and then the difficulty of the task becomes manifest.
|01 - Variations Under Domestication||01-08 - Breeds of the Domestic Pigeons, their Differences and Origin||10||
Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons.
I have kept every breed which I could purchase or obtain, and have been most kindly favoured with skins from several quarters of the world, more especially by the Hon. W. Elliot from India, and by the Hon. C. Murray from Persia.
Many treatises in different languages have been published on pigeons, and some of them are very important, as being of considerable antiquity.
I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs.
The diversity of the breeds is something astonishing.
Compare the English carrier and the short-faced tumbler, and see the wonderful difference in their beaks, entailing corresponding differences in their skulls.
The carrier, more especially the male bird, is also remarkable from the wonderful development of the carunculated skin about the head; and this is accompanied by greatly elongated eyelids, very large external orifices to the nostrils, and a wide gape of mouth.
The short-faced tumbler has a beak in outline almost like that of a finch; and the common tumbler has the singular inherited habit of flying at a great height in a compact flock, and tumbling in the air head over heels.
The runt is a bird of great size, with long massive beak and large feet; some of the sub-breeds of runts have very long necks, others very long wings and tails, others singularly short tails.
The barb is allied to the carrier, but, instead of a long beak has a very short and broad one.
The pouter has a much elongated body, wings, and legs; and its enormously developed crop, which it glories in inflating, may well excite astonishment and even laughter.
The turbit has a 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, 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 tailfeathers, instead of twelve or fourteen- the normal number in all the members of the great pigeon family: 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 be specified.
|01 - Variations Under Domestication||01-08 - Breeds of the Domestic Pigeons, their Differences and Origin||20||
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 caudal and sacral vertebrae vary in number; 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 the wing and tail to each other and to the body; the relative length of the leg and foot; the number of scutellae 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, and in some breeds the voice and disposition, differ remarkably.
Lastly, in certain breeds, the males and females have come to differ in a slight degree from each other.