Art. XXI.—On Hybridism.
[Read before the Hawke's Bay Philosophical Institute, 26th October, 1900.]
The study of hybridism, when such can be systematically and successfully followed out, will no doubt be one of the great factors whereby we shall in a great measure obtain a more correct insight into the secrets of creation and the origin of species. By inference we can conclude that all vegetable and animal life having kindred affinities has descended to our time along the one ancestral line. Take the ruminants, for instance, whose internal conformation is so arranged that they are fitted to chew the cud, and so are enabled to hurriedly collect food-materials with which they retire to a secluded or favourite “camp,” where they contentedly put it all through the mill a second time: it is not possible for us of the present time to hold any theory admitting of a separately distinct creation of all the many species of ruminants; rather we assume they are all descended along the branches of the one ancestral tree. Admitting such descent along the same ancestral line, we are confronted by these problems: Why do closely allied species not breed together in a state of nature? At what stage did they lose the sexual instinct between a newly formed species and that from which it had immediately descended? Was it necessary for either species to be geographically divided? What influence— atmospheric, geographic, or otherwise—caused species to differentiate, and why do we now find all species stable, and incapable of throwing off a further distinct species?
At the present time species may vary within certain limits only—for instance, among the domestic sheep we find many
varieties, but they still remain sheep, and the numerous kinds are all mutually fertile, though in many instances differing greatly in size or appearance one from the other, and the fact of their mutual fertility proves them to be varieties of the one species and not the evolution of new species.
Considering the great advance made in all branches of science during the last fifty years, it is not safe to assert that the limit of any particular branch of study has been already attained; rather let us keep watch for any opening which may give us a clue to the object desired. The subject of hybridism is of great interest to the breeders of domestic animals; and, if the reason for the unfertility of such animals should be at a future time properly understood and removed, there is every probability that useful domestic animals other than those we now possess might be added to our possessions. At present the ordinary mule, obtained by crossing the mare with the ass, is the only useful hybrid in the service of man; but Professor Ewart, of Edinburgh, is at present engaged in experiments hybridizing the horse and the zebra, and some very useful animals have resulted, such as might, if in sufficient numbers, be of great service in South Africa, where the horse is specially subject to certain diseases.
The study of hybridism is as yet only in its infancy, and should embrace the breeding-together of more than two allied species. For instance, Darwin mentions that a hybrid ass and zebra produced offspring by the horse; and in the Zoological Gardens at Regent's Park the bull, the gyall, and the American bison have been joined in the one animal. But to carry out such experiments on a sufficient scale to insure success should be a national undertaking; the lifetime of one or two enthusiasts is far too short and persons having such tendencies seldom are supplied with sufficient capital.
It is noticeable how men of science are at times led astray by the writings of others, especially of those who lived in olden times and in foreign countries. Take the following extract from “Darwinism,” by Alfred R. Wallace (page 163): “Geoff. St. Hilaire was the first to mention, I believe, that in different parts of South America the ram is more usually crossed with the she goat than the sheep with the he goat. The well-known ‘pellones’ of Chili are produced by the second and third generations of such hybrids” (Gay, Hist. de Chile, vol. i., page 466—Agriculture, 1862). Hybrids bred from goat and sheep are called in French “chabin,” and “cabruno” in Spanish. In Chili such hybrids are called “carneros lanudos”*; their breeding inter se appears to be not always
[Footnote] * “Carneros lanudos” is Spanish for “wool-bearing sheep”—i.e., the alpaca—as a distinetion from the llama, which has no fleece. Compare with Latin carnis, flesh; lana, wool = woolly mutton.
successful, and often the original cross has to be recommenced to obtain the proportion of three-eighths of he goat and five-eighths of sheep or of three-eighths of ram and five-eighths of she goat, such being the reputed best hybrids.
And take this extract from “The Angora Goat,” an American publication, by John L. Hayes (page 131): “The Alpaca and its Congeners.—When the Spaniards under Pizarro made the conquest of Peru in 1533 they found in the country four species of animals a little different from each other, to which from their coarse resemblance to the domestic sheep, they gave the name of 'sheep of the country’ (carneros de la tierra). Two of the species—the llama and the alpaca —had been in a state of domestication among the natives; … the two others—the guanaco and the vicuna—lived wild in the high mountains of the Andes.” Mr. Ledger says all four species are fertile together—the wild vicuna seeks the female alpaca at rutting-time.* At page 137 Mr. Hayes quotes from the old-time Spanish writer Pedro de Cieza de Leon as follows: “It appears to me that in no part of the world have sheep like those of the Indians been found or heard of. These sheep are among the most excellent creatures that God has created, and the most useful…. To supply this need the giver of all good things, who is God our Lord, created such vast flocks of these animals, which we call ‘sheep’, that if the Spaniards had not diminished their number in the wars there would be no possibility of containing them.”
Quoting from “On Colonial Wools,” by Thomas Southey (1848): “It is said that not only are hybrids between the goat and sheep common in Chili and Peru, but that in those countries goats and sheep are mated intentionally to produce them.” He also quotes Dr. Adam Smith (” Peru as it is,” 1839), to the effect that “in Chili it has been frequently found that by crossing the goat with the sheep the fleece has resulted of a long lank, lustrous, and consistent quality, and when woven has greatly imitated the finest camlets. The intention of this was originally to avoid the tedious process of plaiting the sheep's fleece on the skin to make it suitable for ‘pellones,’ or saddle-covers, and the experiment succeeded beyond expectation. The best and largest ‘ pellones’ come from Arauca, where the Indians, chiefly leading a pastoral life, take great care in selecting the best breeds for mixture, and in preparing them (by a peculiar method) for their own use and for the purposes of trade. The skins are large, light when dry, and the wool is allowed to grow to a great length
[Footnote] * Mr. Ledger imported these animals to Australia some fifty years ago, and made a special study of their habits in their native land.
(10 in. or 12 in. at times) before the animals are killed. The-colour is generally bluish. They are used as covers for the deep saddles of those countries, sometimes three or four skins-being thrown over one saddle, and in the sudden and violent rains which are common there these ‘pellones’ are found useful as a shelter for rider and horse.”
I think we may safely come to the conclusion that the sheep and goat hybrids here mentioned were the domesticated alpaca, which gave the required length of wool even in the time of the Peruvian Incas. The animals are ruminant, but are more allied to the camel than to the sheep, having two-toes on either foot, and not hoofs.
I read that the first marketable fabric from alpaca wool was made in Europe about 1832 by Benjamin Outram, of Greetland, near Halifax, England. In 1839 Mr.(afterwards Sir) Titus Salt was the only spinner of alpaca yarn in Bradford.
A further instance of mistakes made by old-time authors-is found by quoting Pliny, who says that in his time the Corsican goat interbred with the sheep. This is easily corrected. Here, without doubt, the wild sheep indigenous to the Island of Corsica, called the “mufflon” —a true sheep— is mistaken for a goat. If Pliny had not mentioned Corsica. his mistake would not have been so readily detected.
Mr. Low, in “Domesticated Animals of Great Britain, says, “It has been long known to shepherds, though questioned by naturalists, that the progeny of the cross-between the sheep and goat is fertile. Breeds of this mixed race are numerous in the North of Europe.” Dr. A. R Wallace remarks, “Nothing appears to be known of such hydrids either in Scandinavia or in Italy.”
That such sheep hybrids may occasionally occur is not to be denied. The naturalist Buffon (“Supplement,” tom. iii., p. 7, 1756) obtained one such hybrid in 1751 and eight in 1752. Sanson (“La Culture,” vol. vi., p. 372, published 1865) mentions one in the Vosges, France.
I may here remark that many persons, through ignorance and the remnant of some ancient superstition, consider that the breeding of hybrids is incestuous, and contrary to the laws of God—quite overlooking the fact that the ruler of all things himself can decide whether such things shall occur or not with or without the intervention of man. Possibly not one of such prejudiced, persons could quote the biblical command given to the Jews—“Thou shalt not suffer thine animals to gender with diverse kinds.” The most remarkable point in this command appears to be in the fact that to produce hybrids is a most difficult matter, and therefore hardly worthy of special legislation. In any case, such a superstition in the hands of
the ignorant, so far as my experience goes, is likely to cause any such lusus naturæ to be put to death.
Mr.S. C. Cronwright Schreiner, in “The Angora Goat,” published at the instance of the South African Goat-breeders’ Society in 1898, says, “Crossing between the goat and sheep is not unknown in Cape Colony. I have seen four animals represented as being the hybrid progeny of such a cross—three exhibited at Port Elizabeth shows and one at the Queenstown show—all, I believe, purporting to be crosses between the Angora goat and the Cape (Africander) sheep. That exhibited at Queenstown was said to be such a cross. I examined it closely, and am quite satisfied it was a hybrid between an Angora and a sheep, probably an Africander sheep. It was a-well-grown animal, about six or eight months old, not having yet cut its teeth”—(i.e., its two middle teeth of the mature-mouth, indicating the age of eighteen months or thereabout, as is the case in both sheep and goats)—“and was fat and healthy. Looked at not too critically from a few yards-distance it would be mistaken for a sheep, owing mainly to the shape of the horns, which were curled close to the skull, imparting to the head a sheep-like appearance, and to the fleece, which had an even ‘top’, and showed no ringlets. When examined closely, however, the face, though covered with soft down and quiet in expression, more resembled a goat's, and the compact fleece when opened was found to be mohair, peculiar looking and crimped somewhat like wool, but undoubtedly mohair, about 2 in. in length—the inch length nearest the skin being bright lustrous-yellow, the colour due, no doubt, to the exudation of some natural secretion of the skin. The animal's legs were not woolled.”
This description of the Angora-Africander sheep hybrid would at first sight seem to be clear and sufficient, but when we remember that the Angora and Africander sheep carry no wool or down on the face, and that the latter has no wool on any part of its body, the question arises, From which parent is the face covered with soft down inherited? Somewhat of that style of face might be found among high-class merinos, but all or most other breeds of sheep have the face covered in short hairs, excluding the tuft or topknot between the ears, which in certain breeds is a fair wool, and in others is entirely wanting. Possibly Mr. Schreiner wrote the description of this animal from memory, some time after seeing it.
Of the genus Bos, or oxen, nearly all the different species are mutually fertile with each other andinter se, excepting the Indian buffalo and the European bison, sometimes called the “Aurochs.” This latter animal, I believe, has never been successfully tamed or subdued by man. A cross between the Indian zebu, or humped ox, and our domestic oxen is said to
have been the original foundation of most of the large herds of oxen now inhabiting Tasmania. Various species ofBos may have originally been domesticated by primitive man, obtained in lands wide apart, so far back as the Neolithic or Polished Stone age. These different species have, no doubt, in many cases been accidentally interbred one with the other as man migrated from place to place, according to the exigencies of the time in which they lived; and so new breeds of oxen were originated of whose origin we have now no record.
I consider that the laws of hybridism should be systematically studied, and that before long scientists will understand that hybridism can be worked among kindred races of animals on similar lines to those of hand fertilisation, now successfully carried out by the horticulturist among plants, but that among animals the service of one female will require to be transferred to a female of the kindred race.
I may here mention my own experiment in endeavouring to produce hybrids between the sheep and the Angora buck goat by placing twelve ewes (all of which, excepting one crossbred Lincoln-merino, were pure merino) in a well-fenced paddock (field) with two twelve-month-old Angora bucks. To insure their remaining with the sheep, one of the young bucks was fastened by a dog-coupling chain and collars to one of the strongest ewes, which caused his mate, the other buck, to become accustomed to feed with the sheep, and there appeared every chance of some hybrid offspring resulting; but when the season for lambing came round none of the ewes dropped a lamb. Keeping these same animals together, and adding to them twelve other ewes (making a total of twenty-four), a similar trial was made during the following season, and from the activity of the buck running free every expectation of a successful result was entertained; but later on a merino ram was turned into the paddock, and each ewe produced a late lamb from the merino ram.
After several years’ trial I raised fertile hybrids between the common European domestic duck, which no doubt are the result of domestication from the wild duck or mallard of Europe (Anas boschos), and the male of the New Zealand grey-duck (A. superciliosa). These I have bred together (inter se) for some fifteen years, and they still remain fertile. They are intermediate in size between the two pure breeds, and so far have shown no inclination to interbreed with the wild grey-duck, though (as at the present time) there are usually six to nine of the wild birds on the same small pond which come and go at will. If the hybrid drakes were taken away I have little doubt that some of the grey-drakes would mate with the hybrid ducks. At the same time I feel assured that if
the common domestic duck were allowed on the pond they would intermix with the hybrids readily. The grey-ducks, being smaller than the hybrids, are made to keep their distance by the larger birds, though still passing backwards and forwards among the hybrids on the pond
In trying to breed for the light-green speculum seen on the wing of the grey-duck in preference to the green-blue of the domestic duck, the result has been that the top coverts of the wing-bar are white, while the pen-feathers are becoming grey-brown edged with white in place of the green-blue; so that by further selection a white speculum might be obtained, or, on the other hand, the speculum would be obliterated, the entire wing becoming similar to the colour of the rest of the bird's plumage.
Among these hybrids two instances of very old ducks becoming barren and assuming the plumage of the male have been noted. The first showed full male plumage, even to the curled tail-feathers, excepting that the neck and head still retained their original colour. The duck now alive never gets the speckled white breast or back-feathers perfect; her head and neck inclines to green, and the tail and tail-coverts are blackish as in the mallard, and she has also the curled feathers. In both ducks the bill retained its colour of yellow and black, and did not become green, as in the perfect drake. The bill and legs of the A. superciliosa are blackish, and it is notable that the hybrid ducklings have dark down with black legs and bill, although when mature their legs become orange yellow. From nine to eleven young are hatched out by these hybrids after inbreeding for many years; but they seldom nest a second time during the one season.
The drakes have the breast, thighs, and back of speckled white feathers; neck and head, the green of the mallard. I have tried to breed out the white neck-ring and the chestnut breast which occasionally appears. The tail and coverts are blackish. The ducks are of two shades of yellow-brown, each feather beautifully marked by dark lines or spots. The lighter-coloured ducks seemingly correspond with the chestnut-breasted drake. Why there should be a number of ducks uniform in colour of a light shade, and others equally uniform of a darker shade and with somewhat different markings on each feather, I am at a loss to decide. There are none of various or intermediate colours—just the two shades of colour, and of the two the light-coloured ducks are somewhat larger than the others.
Comprised in the small museum of curios collected in the entrance-hall of the Tavistock Hotel, Waipukurau, Hawke's Bay, is a very handsome specimen of a female hybrid of the third generation from the domestic duck crossed with the
New Zealand grey-duck, and the progeny again bred to the grey-duck. This bird I lost when travelling to my present location some twelve or more years ago. It is of a white colour, slightly shaded about the breast with yellowish-grey, but very lightly—scarcely perceptible; speculum or wing-bar green, as that of the grey-duck; bill and legs blackish. The mother of this bird was very similar to the wild grey-duck, both in size and colour, and her second laying of eggs always produced these white shaded birds, but only two were ever reared to maturity—this duck and a small-sized drake of similar but rather more rufous shading on the breast; speculum also a like shade of bright-green.
The following newspaper-cutting is of interest: “Mr. De Lautour, the present curator of the Masterton Fish-hatcheries, alleges that the indiscriminate use of male fish in impregnating trout-ova in the past has resulted in the production of ‘mules’, and that male fish suitable for breeding are scarce inconsequence. Spawning for present season is nearly completed at the Masterton Fish-hatcheries. So far 410,000 brown-trout eggs have been secured, and 10,000 are hatched; 185,000 rainbow eggs, and 25,000 hatched to date. The largest fish secured for stripping by the curator, from the Ruamahunga River, was a female fish weighing 11 ¾ lb.; the largest male fish secured weighed 9 ¾ lb.” Judging from the remarks here made I would suppose that these “mule” fish were perfectly barren and unable to produce milt, whilst the female “mules” would in like manner be deficient in spawn. This would indicate that in hybrid fish of the same genus the fiat “Thus far and no further” was clearly defined.
I have two plants in my garden, growing very much greenery and 6 ft. in height, just coming into flower—biennial. They are from a radish fertilised naturally from one of the cabbages, but, like plants grown seven years ago, they will have no seed.