Chapter IX: Section I: The Breeding of Stock

_Cross Breeding._--For many years past feeders have zealously occupied themselves in the improvement of their stock, and the result of their labors is observable in the marked superiority of the breeds of the present day over their ancestors in the last century. The improvement of animals designed as food for man is effected by keeping them on a liberal dietary, by selecting only the best individuals for sires and dams, and by combining the excellencies of two or more varieties of a species in one breed. A species consists of a number of animals which exhibit so many points of resemblance, that they are regarded by the great majority of naturalists to be the descendants of a single pair. If we except the believers in the hypotheses relative to the origin of existing varieties of animals and plants, propounded by Lamarck, Darwin, and other naturalists of the "advanced school," there is a general belief in the immutability of species. The individuals of an existing species, say dogs, can never acquire the peculiar features of another species; nor can their descendants, if we except hybrids, ever become animals in which the characteristics of the dog tribe are irrecognisable. By various influences, such as, for example, differences in food and climate, and domestication, a species may be split into _varieties_, or _breeds_, all of which, however, retain the more important characteristics of the primordial type. There appears to be no limit to the varieties of dogs, yet one can perceive by a glance that there is no specific difference between the huge Mont St. Bernard dog and the diminutive poodle, or between the sparse greyhound and the burly mastiff. All the varieties of our domestic fowl have been traced to a common origin--the wild Indian fowl (_Gallus bankiva_). Even Darwin admits that all the existing kinds of horses are, in all probability, the descendants of an original stock; and it is generally agreed that the scores of varieties of pigeons own a common ancestor in the rock pigeon (_Columba livia_).

As certain individuals are grouped by naturalists into species, so particular species, which in habits and general appearance resemble each other, are arranged under the head of genus. The horse, the ass, and the zebra are formed on nearly the same anatomical plan; they are therefore classed together, and designated the genus _Equus_, a term derived from the Latin word _equus_, a horse--that animal being regarded as the type, or perfect member of the group. Thus the horse, in the nomenclature of the naturalist, is termed _Equus caballus_; the ass, _Equus asinus_; and the zebra, _Equus zebra_. By a further extension of this principle of classification, very closely allied genera are united under the term of _family_.

The different varieties of the same species breed, as might be anticipated, freely together; but it frequently happens that two individuals of different species pair, and produce an animal which inherits some of the properties of each of its progenitors. These half-breeds are termed _hybrids_, or _mules_, and we have familiar examples of them in the common mule and the jennet. As a general rule, animals exhibit a disinclination to breed with other than members of their own species; and although the interference of man may overcome this natural repugnance, he can only effect the fruitful congress of individuals belonging to closely allied species, being members of the same genus. Hybrids in the genus _Equus_ are very common. A cross has been produced between the he-goat and the ewe; the camel and the dromedary have bred together; and Buffon succeeded in producing a hybrid in which three animals were represented--namely, the bison, the zebu, and the ox. On the other hand, attempts to effect a cross between animals belonging to different families have generally failed; nor is it at all probable that a cross will ever be produced between the pig and the sheep, between the horse and the cow, or, most unlikely of all, between the dog and the cat.

It is the general belief that hybrids are sterile, or, at least, that they are incapable of propagation _inter se_. This may be true with respect to the hybrids of species not very closely allied; but that there are exceptions to the rule is quite clear from Roux's experiments with hares and rabbits. This gentleman, who is, or was, the president of a French agricultural society, but who makes no profession of scientific knowledge, has succeeded, after several failures, in producing a fruitful cross between the rabbit and the hare. This hybrid has received the name of leporide (from the Latin _leporinus_, pertaining to a hare), and it is different from former crosses, in being five parts hare, and three parts rabbit. M. Roux has bred this hybrid during the last eighteen years, and has not observed the slightest appearance of decay of race manifest itself up to the present, so that, for all practical purposes, the leporide may be regarded as an addition to the distinct species of animals. The leporide fattens rapidly, and with but little expenditure of food. Sold at the age of four months, it realises, in France, a price four times greater than that commanded by a rabbit of the same age; and at a year old it weighs on an average ten pounds, and sometimes as much as sixteen pounds. It breeds at four months, continues thirty days in gestation, and yearly produces five or six litters of from five to eight young. To produce this hybrid is by no means difficult. A leveret, just old enough to dispense with the maternal nutriment, should be placed with a few doe rabbits of his own age, apart from other animals. He will soon become familiar with the does, and when they attain the age of puberty, all the rabbits save one or two should be removed. Speedily those left with the hare will become with young, upon which they should be removed, and replaced by others. After this the hare should be kept in a hutch by himself, and a doe left with him at night only. As the hare is naturally a very shy animal, it will only breed when perfect quietness prevails. The half-bred produced in the first instance should now be put to the hare, and a cross, three parts hare, and one part rabbit, obtained. The permanent breed should then be obtained by crossing the quadroon doe leporide, if I may use the term, with the half-bred buck.

I have directed attention to the production of the leporide because I believe that the problems in relation to it, which have been solved by M. Roux, have an important bearing upon the breeding of animals of greater importance than hares and rabbits. Here we find a race of animals produced by the fusion of two species, which naturally exist in a state of mutual enmity, and which differ in many important respects. The hare and the rabbit are respectively of but little value as food, at least they are of no importance to the feeder; yet a cross between them turns out to be an excellent meat-producing animal, which may be reared with considerable profit to the feeder. It is thus clearly shown that two kinds of animals, neither of which is of great utility, may give rise to an excellent cross, if their blood, so to speak, be blended in proper proportions. A half-bred animal may be less valuable than its parents, but a quadroon may greatly excel its progenitors. The goat and sheep are so closely related that they are classed by naturalists under one head--_Capridae_. Some kinds of sheep have hair like goats, and certain varieties of goats have fleeces that closely resemble those on the sheep. There are sheep with horns, and goats without those striking appendages. The Cape of Good Hope goat might easily be mistaken for a sheep. It would seem, judging by the results of Roux's experiments, that there is no great difficulty in the way of obtaining a cross between the sheep and the goat. I do not mean an ordinary half-breed, but a prolific hybrid similar to the leporide. Of course, it is impossible, _a priori_, to say whether or not such a hybrid race, supposing it produceable, would be valuable; but as goats can find a subsistence on mountains where sheep would starve, it is possible that an animal, essentially a sheep, but with a streak of goat blood in it, could be profitably kept on very poor uplands. Whether a race of what we might term _caprides_ be formed or not we have derived most suggestive information from M. Roux's experiments, which I hope may be turned to account in what is by far the most important field of enquiry, the judicious crossing of varieties of the same species.

It is a _quaestio vexata_ whether or not the parents generally exercise different influences upon the shape and size of their offspring. Mr. Spooner supports the supposition--a very popular one--that the sire gives shape to the external organs, whilst the dam affects the internal organisation. I have considerable doubt as to the probability of this theory. The children who spring from the union of a white man with a negress possess physical and intellectual qualities which are nearly if not quite the _mean_ of their parents; but the offspring of parents, both of the same race--be it Caucasian, Mongolian, or Indian--frequently conform, intellectually and corporeally, to either of their progenitors. Thus, of the children of a tall, thin, dark man, and a short, fat, fair woman, some will be like their father, and the others will resemble their mother, or, perhaps, all may "take after" either parent. Sometimes a child appears to be in every respect unlike its parents, and occasionally the likeness of an ancestor appears in a descendant, in whom no resemblance to his immediate progenitors can be detected. It is highly probable that both parents exercise, under most circumstances, a joint influence upon the qualities of their offspring, but that one of them may produce so much greater an effect that the influence of the other is not recognisable, except perhaps to a very close observer. But I doubt very much that any particular organ of the offspring is, as a rule, more liable to the influence of the sire than of the dam, or _vice versa_; and the breeder who believes that the sire alone is concerned in moulding the external form of the offspring, and who consequently pays no attention to this point in the dam, will often find himself out in his reckonings. In order to be certain of a satisfactory result, the dam should in every respect be equal to the sire. In practice, however, this is not always the case, for as sires are so few as compared with the number of dams, the greatest efforts have been directed towards the improvement of the former.

There is, or ought to be, a familiar maxim with breeders, that "like begets like, or the likeness of an ancestor." This is a "wise saw," of which there are many "modern instances:" the excellencies or defects of sire or dam are certain to be transmitted through several generations, though they may not appear in all. As a general rule, good animals will produce a good, and defective animals a defective, offspring, but it sometimes happens that a bull or cow, of the best blood, is decidedly inferior, whilst really good animals are occasionally the produce of parents of "low degree." If the defects or excellencies of animals were ineradicable there would be no need for the science of breeding; but by the continual selection of only the most superior animals for breeding purposes the defects of a species gradually disappear, and the good qualities are alone transmitted. As, however, animals that are used as food for man are to some extent in an abnormal condition, the points which may be excellencies in that state, would not have been such in the original condition of the animal. We find, therefore, that the improved breeds of oxen and sheep exhibit some tendency to revert to their original condition, and it is only by close attention to the diet, breeding, and general management of these animals that this tendency can be successfully resisted. Sometimes, however, an animal of even the best breed will "return to nature," or will acquire some undesirable quality; such an animal should be rejected for breeding purposes, for its defects would in all probability be transmitted to its descendants, near or remote. A case, which admirably illustrates this point, is recorded in the _Philosophical Transactions_ for 1813, and it is sufficiently interesting to be mentioned here:--

Seth Wright, who possessed a small farm on the Charles River,
about sixteen miles from Boston, had a small flock, consisting
of fifteen ewes and one ram. One of these ewes, in 1791, produced
a singular-shaped male lamb. Wright was advised to kill his former
ram and keep this new one in place of it; the consequence was, the
formation of a new breed of sheep, which gradually spread over a
considerable part of New England, but the introduction of the Merino
has nearly destroyed them again. This new variety was called the
Otter, or "Ankon" breed. They are remarkable for the shortness of
their legs, and the crookedness of their forelegs, like an elbow.
They are much more feeble and much smaller than the common sheep,
and less able to break over low fences; and this was the reason
of their being continued and propagated.

Here we have an instance of an animal propagating a defect through a great number of descendants, though it had not acquired it from its own ancestors. It is, however, probable that occasionally a male descendant of this short-legged ram possessed considerably longer organs of locomotion than the founder of his breed; and, consequently, if selected for breeding purposes might become the founder of a long-legged variety, in which, however, a couple of pairs of short-legs would occasionally present themselves. I have a notion that the higher animals are in the scale of being, the greater is their tendency to transmit their acquired good or bad habits to their posterity. Dogs are, perhaps, the most intelligent of the inferior animals, and it is well known that they transmit to their offspring their acquired as well as their natural habits. I doubt very much that those most stupid of creatures, guinea-pigs, possess this property in any sensible degree; or, indeed, that like the canine tribe, they can be readily made to acquire artificial peculiarities: but there once flourished a "learned pig," and it would be worth inquiring whether or not its descendants, like the descendants of the trained setter, and pointer, were at all benefited by the education of their ancestor. I shall conclude this part of my subject in the words of Professor Tanner: "In all cases where the breed has been carefully preserved pure, great benefit will result from doing so. The character of a breed becomes more and more concentrated and confirmed in a pedigree animal, and this character is rendered more fully hereditary in proportion to the number of generations through which it has been transmitted. By the aid of pedigree, purity of blood may be insured, and a systematic plan adopted by which we can perpetuate distinct families, and thereby obtain a change of blood without its being a cross. It is evident that any one adopting a systematic arrangement will be able to do this more effectually than another without this aid. This is the more important when the number of families is small, as is the case with Devons and Herefords, especially the former. The individual animals from which the Devons are descended are very limited in number, and in a few hands; but, with some honourable exceptions, little attention is given to this point. The importance is rendered evident by the decreasing size of the breed, the number of barren heifers, and the increased delicacy of constitution shown in the stock of many breeders of that district who are not particular in this respect. The contrast between such herds, and those in which more care and judgment are exercised, renders the advantages of attention to pedigree very evident; for here the strength of constitution is retained, together with many of the advantages of this valuable breed."