Massachusetts, produced a male lamb, which, from singular length of body and shortness of legs, attracted attention. It was amongst the sheep much what a Skye terrier is amongst dogs. The peculiarity of its shape incapacitated the animal from leaping fences, and therefore it was considered desirable that the same shape should be given to all the members of a flock. Wright determined to try whether this could not be effected by breeding with this ram, and in the first year he succeeded in obtaining two lambs of the same peculiar conformation. In subsequent years the numbers increased, and by causing them to breed with one another, a strongly marked variety of sheep, before unknown to the world, was thus established. It was first called the otter breed, and from the curvature of the forelegs, which had the appearance of elbows when the animal was walking, Dr. Shuttack gave the variety the name of the ancon sheep. So strongly was the transmission of this peculiarity by inheritance shown, that a common ewe has been known to produce, by an ancon ram, one lamb of the usual shape, and one a marked specimen of the long-backed and short-legged variety.

In one or two particulars, certainly, this is not a common case. It is a rare thing for a striking variety to spring as suddenly as this into existence, and it is singular that the peculiarity should be preserved unmixed in the cross or half-breed; but in other respects the story is common-place enough, and only represents what men do every day with their cattle, poultry, horses, and dogs, and what is done by every nursery gardener in rearing plants. Whenever a breeder sees any peculiarity appear amongst his animals which he considers valuable, he carefully preserves the individual that shows it, and by pairing with other individuals that manifest a tendency towards it, and selecting such of the offspring as have most perfectly inherited it, he succeeds in perpetuating and greatly improving it.

That such is the case to a certain extent every one knows: the very talk about thoroughbred horses and dogs, and pedigrees, and the reports of cattle shows, all prove it. But the extent to which it is true, and the enormous power of changing the organization of an animal which results from a careful selection in breeding, few people who have not had much personal experience can fully appreciate.

"Youatt, who was probably better acquainted with the works of agriculturists than almost any other individual, and who was himself a very good judge of an animal, speaks of the principle of selection as that which enables the agriculturist, not only to modify the character of his flock, but to change it altogether. It is the magician's wand, by means of which he may summon into life whatever form and mould he pleases.' Lord Somerville, speaking of what breeders have done for sheep, says: It would seem as if they had chalked out upon a wall a form perfect in itself, and then had given it existence.' That most skilful breeder, Sir John Sebright, used to say, with respect to pigeons, that he would produce any given feather in three years, but it would take him six years to obtain head and beak.' In Saxony the importance of the principle of selection in regard to merino sheep is so fully recognised, that men follow it as a trade the sheep are placed on a table and are studied, like a picture by a connoisseur; this is done three times at intervals of months, and the sheep are each time marked and classed, so that the very best may ultimately be selected for breeding."-p. 31.

The same thing may be quite unconsciously but as efficaciously done, simply by the preference that every one naturally gives to the best animals or plants, by which, without any direct intention of modifying or improving the breed, the better sorts are alone permitted to reproduce. No amount of cultivation suddenly bestowed upon a wild plant would produce our garden fruits or flowers. It is the continued influence of care on many generations, and the preference for the best specimens for preservation, that have produced such an impression upon our domesticated plants, that in a vast number of cases their wild parent stocks cannot be recognized.

Of domestic animals those of which the varieties are the most remarkable, both on account of the immense number and strikingly divergent characters of the variations, and from the universal occurrence of the rule that like produces its like, are dogs and pigeons. What can be more unlike than a Newfoundland, or Mount St. Bernard, a common and Italian greyhound, a Skye terrier and a King Charles's spaniel or a Blenheim? Yet there is no perceptible tendency in one sort of dog to produce young resembling those of another breed. On this a very strong argument could be founded, if we were assured that all domestic dogs sprung from the same wild stock; but this is an instance in which Mr. Darwin shows his superiority to ordinary theorists, and the trustworthiness we may attribute to the facts he adduces in favour of his system,

for he tells us that it is his belief "that our dogs have descended from several wild stocks." (p. 254.) At any rate the changes that have taken place in them since they first became man's companions, must be very great, for no wild dog resembles a bloodhound, a terrier, or a spaniel, more nearly, or perhaps as nearly, as it does the wolf, or even the fox.

As there seems no reason to doubt the descent of all our domestic pigeons from the same wild stock, and as their variation from the ancestral form, and from one another, is wonderfully great, they form a very interesting group, and Mr. Darwin has most judiciously chosen it for accurate examination. This is his account of these birds.

"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; soine 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 very long beak, has a very short and very 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 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 esophagus. 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 be 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

The

of the lower jaw, varies in a highly remarkable manner. number of the caudal and sacral vertebræ vary; as does the num ber 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 œsophagus; 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 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.

"Great as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under this term several geographical races or subspecies, which differ from each other in the most trifling respects. As several of the reasons which have led me to this belief are in some degree applicable to other cases, I will here briefly give them. If the several breeds are not varieties, and have not proceeded from the rock pigeon, they must have descended from at least seven or eight aboriginal stocks; for it is impossible to make the present domestic breeds by the crossing of any lesser number: how, for instance, could a pouter be produced by crossing two breeds unless one of the parent-stocks possessed the characteristic enormous crop? The supposed aboriginal stocks must all have been rockpigeons, that is, not breeding or willingly perching on trees. But besides C. livia, with its geographical sub-species, only two or three other species of rock-pigeous are known; and these have not any of the characters of the domestic breeds. Hence the supposed aboriginal stocks must either still exist in the countries where they

were originally domesticated, and yet be unknown to ornithologists; and this, considering their size, habits, and remarkable characters, seems very improbable; or they must have become extinct in the wild state. But birds breeding on precipices, and good fliers, are unlikely to be exterminated; and the common rock-pigeon, which has the same habits with the domestic breeds, has not been exterminated even on several of the smaller British islets, or on the shores of the Mediterranean. Hence the supposed extermination of so many species having similar habits with the rock-pigeon seems to me a very rash assumption. Moreover, the several above-named domesticated breeds have been transported to all parts of the world, and, therefore, some of them must have been carried back again into their native country; but not one has become wild or feral, though the dovecot-pigeon, which is the rock-pigeon in a very slightly altered state, has become feral in several places. Again, all recent experience shows that it is most difficult to get any wild animal to breed freely under domestication; yet on the hypothesis of the multiple origin of our pigeons, it must be assumed that at least seven or eight species were so thoroughly domesticated in ancient times by half-civilized man, as to be quite prolific under confinement. "An argument, as it seems to me, of great weight, and applicable in several other cases, is, that the above-specified breeds, though agreeing generally in constitution, habits, voice, colouring, and in most parts of their structure, with the wild rock-pigeon, yet are certainly highly abnormal in other parts of their structure; we may look in vain throughout the whole great family of Columbidæ for a beak like that of the English carrier, or that of the short-faced tumbler, or barb; for reversed feathers like those of the Jacobin; for a crop like that of the pouter; for tail-feathers like those of the fantail. Hence it must be assumed not only that half-civilized man succeeded in thoroughly domesticating several species, but that he intentionally or by chance picked out extraordinarily abnormal species; and further, that these very species have since all become extinct or unknown. So many strange contingencies seem to me improbable in the highest degree."-pp. 21-24.

It was well worth while to extract the whole of this passage, although lengthy, as it supplies us with a key to Mr. Darwin's entire system. That which we see occurring, consciously or unconsciously, amongst men, and with domesticated animals, he supposes must also happen in nature. A pigeon with a crop slightly distended may have attracted the attention of its owner, and by a careful choice of mates, and a selection amongst the young of the birds more remarkable for the same peculiarity, by degrees, and after the lapse of a long term of years, the breed of pouter pigeons has been established.