Part 10

Another bird whose wild ancestor is known with a high degree of certainty is the barn-door fowl. It has sprung from the jungle fowl, Gallus bankiva, and less remotely from the game fowl. Hence, if fowls of different breeds are crossed, the offspring, should reversion occur, ought to resemble either the jungle fowl or their less remote ancestors, the game fowl. A dark red-breasted bantam was crossed with an Indian game Dorking; of the nine chickens which resulted, six resembled Dorkings, and three in both form and colour resembled game birds. Two of the three grew up, and the only visible trace of their parentage was a double comb inherited from their cross-bred father. Here again the reversion does not stop at the colour and form, but extends to disposition; the birds are very shy, and fly about like wild birds. The above are but two instances out of many which might be quoted from the Penycuik experiments; they are, however, unusually clear cases, and should do something to restore confidence amongst recent doubters of reversion.

An animal is said to be prepotent when it strongly impresses its own peculiarities of form, colour, temperament, etc., on its offspring. In the above-mentioned experiment with pigeons the owl had been prepotent over the archangel in the mother of the offspring which showed such marked reversion. There is no factor in breeding of more importance than prepotency, and none which it is more difficult to estimate. The term is necessarily a relative one, and, further, it may affect some characters and not others. Often it must go undetected, as in the case of the leader of a herd of wild cattle, who may be highly prepotent, but whose prepotency, unless he is mated with members of another herd displaying different characters, may pass unnoticed. Breeders claim to be able to produce cattle so prepotent that they will produce their like however mated. A well-known dealer in highly-bred ponies used to boast that he had a filly so prepotent that, though she were sent to the best Clydesdale stallion in Scotland, she would throw a colt showing no cart-horse blood. Prepotency is usually obtained by inbreeding, which up to a certain point fixes the character of a race, and in all cases tends to check variation and reversion--the Jews, for instance, as a race are strongly prepotent--but there is no doubt that it may also arise as a sport, and this is probably its more usual origin in a state of nature. Professor Ewart, however, believes that inbreeding is much commoner among wild animals than has usually been conceded, and he holds the opinion that the prepotency so induced has played a considerable part in the origin of species. This, if true, would to some extent take the place of Romanes’ ‘physiological selection’; for Romanes also thought that, though of great importance, variation and natural selection were insufficient to account for the origin of species without some factor which would help to mitigate the swamping effect of intercrossing--some such agency as the fences of modern farms and cattle-ranches--without which the famous cattle breeds of the world would soon disappear in a general ‘regression towards mediocrity.’

In inbreeding the great difficulty of the breeder is to know when to stop. Carried too far it undoubtedly leads to degeneracy. In the ‘Domesticated Animals of Great Britain,’ Lowe records the case of a gentleman who inbred foxhounds to such an extent that ‘the race actually became monstrous and perished.’ Hogs, if too closely inbred, grow hair instead of bristles; their legs become short and unable to support the body; and not only is their fertility diminished, but the mothers cannot nourish the young. That infertility is induced by inbreeding is further shown by some experiments of Ritzema Bos with rats. From seven rats of one family and an unrelated male he continued inbreeding for a period of some six years, and bred about thirty generations. The average of the numbers in each litter fell from 7½ in 1887 to 4-7/12 in 1891 and 3⅕ in 1892. Further, the offspring of inbred parents are usually weak. Sir Everett Millais estimated that 60 to 70 per cent. of inbred dogs attacked by distemper were carried off.

On the other hand, inbreeding often succeeds even when carried to what the ordinary man would consider excess. The ‘Herd-book’ contains the following case in point. The bull Bolingbroke and the cow Phœnix were more closely related to one another than half-brother is to half-sister. They were mated, and produced the bull Favourite. Favourite was then coupled with his dam, and produced the cow Young Phœnix; he was then coupled with his daughter Young Phœnix, and the world-famed Comet was the result. Professor Ewart tells us that if there was little crossing in the production of Comet, there was still less in that of Clarissa, the mother of the celebrated Restless. An instance of the faith in close inbreeding which exists in the minds of breeders occurred in a letter which the Field published in 1898, in which the writer stated he had heard ‘Mr. Joseph Osborne, the ablest authority living on English

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thoroughbreds, declare that you cannot now get too much of Birdcatcher.’

So far as is known, no direct investigations have been made to test how far inbreeding may be carried in the Equidæ; but, on the other hand, the breeding of racehorses may perhaps be looked upon as a gigantic experiment in this direction. Our English thoroughbreds can be traced back to a few imported sires--the Byerly Turk, imported in 1689; the Darley Arabian, in 1710; and the Godolphin Arabian, in 1730. Since then, by careful breeding and nutrition, they have increased on an average some 8 or 9 inches in height. There is, however, a widely-spread impression that at present there is a marked deterioration in the staying power and in the general ‘fitness’ of the racer. The falling off is further shown by a fact commented on by Sir Walter Gilbey--viz., ‘the smallness of the percentage of even tolerably successful horses out of a prodigious number bred at an enormous outlay.’ In support of this he quotes a sentence from the Times (December 27, 1897), referring to a sale in which thirty-two yearlings had been sold for 51,250 guineas.

‘These thirty-two yearlings’ (said the Times) ‘are represented by two winners of five races, Florio Rubattino and La Reine, who have contributed about £2,000 to the total cost; and there is not, so far as can be known, a single one of the thirty others with any prospect of making a racehorse.’

If, then, it is true that the English racehorse is on the down grade, what steps should be taken to arrest this descent? Sir Everett Millais restored a pack of basset hounds by crossing them with a bloodhound, the original forefather of bassets. The resulting pups were bassets in form, but not quite bassets in colour; when, however, these cross-breeds were mated with bassets the majority of the pups turned out to be perfect bassets both in shape and coloration. This indicates that one way to rejuvenate the racehorse would be to have recourse to a new importation of the best Arab mares that the plains of Arabia can produce. Breeders hesitate to adopt this course, because their present breed is not only larger, but, over very short distances, fleeter than its forefathers. The shortening of the course in recent years is probably a further sign of the degeneracy of our present racers. Were new blood introduced, and more three-or four-mile races instituted, we should doubtless soon have a return to the champion form of bygone days. Another method would be to import some of the racers of Australia or New Zealand, and cross them with the home product. Different surroundings, food, etc., soon influence the constitution, and this being so, it would be advisable to select those horses of pure descent which have been longest subjected to these altered conditions. Thus the chance of reversion occurring would be increased.

It has been noticed more than once in the preceding pages that a young animal showing reversion is strong and vigorous. It is the belief of dog-breeders that those members of an inbred litter which show reversion are the strongest and best. Similarly, experience shows that if an inbred sire and dam produce a dun-coloured striped foal it almost always turns out well. Reversion is accompanied by a rejuvenescence; it is as though the young animal had appeared at an earlier period in the life-history of the race, before the race had undergone those changes in the way of deterioration which so often accompany inbreeding.

Wild animals are frequently thought to be prepotent over tame ones, but of the eleven zebra-hybrids bred at Penycuik only two took markedly after their sire, the zebra Matopo. There are other experiments recounted which tell the other way, and at present this matter remains in a state of considerable uncertainty. Further experiment may probably show that though in most cases the oldest type is likely to prevail, the offspring may take after the most inbred of its parents. The matter is not altogether as simple as the above statements would imply. For instance, a sport is often strongly prepotent. Standfuss’s experiments in hybridizing butterflies tend to show this, and Mr. Galton even looks upon prepotency as a sport or an aberrant variation. These butterfly experiments also indicate that the male is usually prepotent over the female; but so many questions of nutrition, the maturity of the germ-cells, etc., enter into these intricate problems that it is exceedingly difficult to disentangle the several factors which play a part in the constitution of every living being.

Some years ago it used to be taught that species are infertile inter se; nowadays it almost seems that we are giving up the idea of species altogether. No two naturalists take precisely the same view of what constitutes a species, and no one has succeeded in defining shortly and clearly what a species is. The intersterility test has broken down; the common goose and the Chinese goose, the common duck and the pintail duck, various species of pheasant, the ox of Europe and the American bison or the Indian zebu, not only breed together, but yield hybrids which are themselves fertile; and the same is true of many plants. Why the hybrids of Equidæ should prove sterile is not clear.

This article must not close without a word or two more about the zebra-hybrids. It is mentioned above that only two out of the eleven which have already been born took strongly after their father. This is no proof that the wilder animal is not prepotent. Recent experiments in hybridizing echinoderms, star-fish, seaurchins, etc., show that the hybrid tends to resemble that species whose germ-cells are most nearly approaching maturity; and thus the nutrition of the germ-cell is but another thread in that complex tangle of heredity which must not be overlooked in attempting to estimate the part played by prepotency and reversion.

Those who have seen the young hybrids playing about in the fields at Penycuik must agree that they are the most charming and compactly built little animals possible; ‘marvellous steeds, striped as a melon is, all black and white,’ as the poet has it. Of Romulus, the eldest of the herd, Professor Ewart says:

‘When a few days old was the most attractive little creature I have ever seen. He seemed to combine all the grace and beauty of an antelope and a well-bred Arab foal.... What has struck me from the first has been his alertness and the expedition with which he escapes from suspicious or unfamiliar objects. When quite young, if caught napping in the paddock, the facility with which he, as it were, rolled on to his feet and darted off was wonderful.’

The writer can fully confirm all the praise Professor Ewart lavishes on his pets; in truth Romulus has been well described as a ‘bonnie colt with rare quality of bone ... and with the dainty step and dignity of the zebra.’ Remus, the offspring of the Irish mare, was from the first more friendly than his half-brother; he objected less to the process of weaning, and promised to be the handsomest and fleetest of the existing hybrids.

On the whole the hybrids are unusually hardy; at the time of writing only two have been lost--one, a twin, which died almost as soon as it was born, and

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another which lived some three months and then succumbed. It is only fair to say that the dam of the latter, who was only three years old when the hybrid was born, had been much weakened by attacks of the strongylus worm, and that she was the victim of close inbreeding. Both the zebras and the hybrids which have been under observation at Penycuik show a remarkable capacity for recovering from wounds. Accidental injuries heal with great rapidity. On one occasion the surviving twin was discovered with a flap of skin some five inches long hanging down over the front of the left fetlock. The skin was stitched into its place again, during which operation the little hybrid fought desperately, and cried piteously; but it soon recovered, the wound healed, and now scarcely a scar remains. There was no lameness and no swelling either at the fetlock or above the knee. Some time ago four hybrid colts and three ordinary foals were attacked by that scourge of the stable, the strongylus worm. One of the latter died and another was reduced almost to a skeleton: the hybrids, though obviously affected, suffered much less than the others, and soon recovered. It is further noticeable that the hybrids suffer less from colds and other slight ailments than the mares and horses amongst which they live. Thus it seems that Colonel Lugard’s hope has to some extent proved true. Some years ago, when administering British East Africa, he strongly recommended the breeding of zebra mules from both the horse and the donkey, believing that they would prove exceptionally hardy and possibly impervious to the tsetse fly. So far as Professor’s Ewart’s experiments go, the first part of the forecast has proved correct. Unfortunately, the latter half has not been justified.

The much dreaded tsetse fly, which has interfered so seriously with the colonization of whole tracts of South Africa, is now known not to be the direct cause of the disease which follows its puncture, but to be the means by which the organism which causes the disease is introduced into the body. In this respect the tsetse fly resembles the malarial mosquito. It is not thought that the organism--a hæmatozoon--passes through any of the stages of its life-history within the body of the fly, but that the proboscis of that insect merely acts like an inoculating needle. An answer to the important question, Are zebra-hybrids fly-proof or not? has been attempted. Professor Ewart generously allowed an experiment to be tried on two of his hybrids, which were inoculated with the hæmatozoon, supplied from the Pathological Laboratory at Cambridge. The result was unfortunate, for, although the hybrids resisted the disease far longer than a mare which was also inoculated as a control experiment, both ultimately succumbed.

There is no doubt that it is a comparatively easy matter to breed these hybrids, and that they are not only extremely attractive animals to the eye, but hardy and vigorous, possessed of great staying powers, and promising to be capable of severe work. It is recognized that one of the gravest difficulties which the Indian Army Corps has to contend with is the paucity of mules, both for transport and mountain-battery work; and at the time of the South African War a Commission was busily employed purchasing mules both in Italy and in Texas, and elsewhere. Should these hybrids turn out as well as they at present promise, they may fill a want which is acutely felt by those responsible for the conduct of our frequent ‘small wars,’ and, if bred largely in East Africa, may, as Colonel Lugard suggested, prove a source of wealth and revenue in the future.

We have hitherto said little or nothing about the book itself with which we have been dealing. The larger part consists of three articles reprinted from the Veterinarian and one from the Zoologist; but the more recent and more important half is the General Introduction, covering a hundred pages, in which Professor Ewart sums up the results of his experiments. The form of the work necessarily involves a good deal of repetition, but in so complex a subject this is on the whole rather an advantage than otherwise. Professor Ewart’s style is clear, and his pages abound in apposite illustrations. The book cannot fail to attract both the man of science and the practical breeder.

From what we have said it is evident that the Penycuik experiments are of the highest interest both practical and theoretical, and the public spirit and self-devotion shown by the Edinburgh professor in carrying them out cannot be too widely recognized. The expense of feeding and housing some thirty to forty horses, asses, and zebras is very great, and the initial expenditure in erecting stables, buying land and fencing it, is also considerable. It is, perhaps, not too much to hope that some public body may be willing to undertake at least a part of the burden. The Zoological Society of London possesses, not only the necessary establishment required, including a well-trained staff, but it also has facilities for obtaining all kinds of animals which are far greater than those of any private individual. We hope that the day is not far distant when experiments of this kind will be systematically carried on under the direction of the authorities who control the Gardens in Regent’s Park. Probably such experiments would have better prospects of success at a farm in the country than in London, and there is much to be said for such an experimental farm under the management of a body like the Zoological Society. Apart from the more strictly scientific use to which it might be put, it would serve as a convenient sanatorium for those animals which cannot stand the fogs and damp of London.

PASTEUR

Je suis chimiste, je fais des expériences et je tâche de comprendre ce qu’elles disent.--PASTEUR.

As one walks down the Rue des Tanneurs, in the small provincial town of Dôle, where the main line from Paris to Pontarlier sends off a branch north-east towards Besançon, a small tablet set in the façade of a humble dwelling catches the eye. It bears the following inscription in gilt letters: ‘Ici est né Louis Pasteur le 27 décembre 1822.’

Pasteur came of the people. In the heraldic meaning of the term, he was emphatically not ‘born.’ His forbears were shepherds, peasants, tillers of the earth, millers, and latterly, tanners. But he came from amongst the best peasantry in Europe, that peasantry which is still the backbone of the great French nation. The admirable care with which records are preserved in France has enabled Pasteur’s son-in-law and latest biographer to trace the family name in the parish archives back to the beginning of the seventeenth century, at which period numerous Pasteurs were living in the villages round about the Priory of Mouthe, ‘en pleine Franche-Comté.’

The first to emerge clearly from the confused cluster of possible ancestors is a certain Denis Pasteur, who became miller to the Comte d’Udressier, after whom he doubtless named his son Claude, born in 1683. Claude in his turn became a miller, and died in the year 1746. Of his eight children, the youngest, Claude-Étienne, was the great-grandfather of Louis Pasteur. The inhabitants of Franche-Comté were, in large part, serfs--‘gens de mainmorte,’ as they termed them then. Claude-Étienne, being a serf, at the age of thirty wished to enfranchise himself; and this he did in 1763, by the special grace of ‘Messire Philippe-Marie-Francois, Comte d’Udressier, Seigneur d’Ecleux, Cramans, Lemuy, et autres lieux,’ and on the payment of four louis-d’or. He subsequently married and had children. His third son, Jean-Henri, who for a time carried on his father’s trade of tanner at Besançon, seems to have disappeared at the age of twenty-seven, leaving a small boy, Jean-Joseph Pasteur, born in 1791, who was brought up by his grandmother and his father’s sister.