Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
|
See also:TELEGONY (Gr. TT/Xe, far, and yovos, offspring) , the name now given to the See also:hypothesis that offspring sometimes inherit characters from a previous See also:mate of their See also:dam . Until See also:recent years the supposed See also:inheritance of characters acquired by a dam from one or more of her former mates was usually designated by breeders " throwing back "; by physiologists, " infection of the germ," or simply " infection." The See also:doctrine of " infection," like the somewhat allied doctrine of " maternal impressions," seems to be alike See also:ancient and widespread . See also:Evidence of the antiquity of the belief in " maternal impressions " we have in See also:Jacob placing peeled rods before Laban's See also:cattle to induce them to bring forth " See also:ring-straked speckled and spotted " offspring; evidence of the antiquity of the " infection " doctrine we have, according to some writers, in the practice amongst the Israelites of requiring the childless widow to marry her deceased See also:husband's See also:brother, that he might " raise up See also:seed to his brother." Whatever may have been the views of stock-owners in the remote past, it is certain that during the See also:middle ages the belief in " infection " was See also:common amongst breeders, and that during the last two centuries it met with the See also:general approval of naturalists, See also:English breeders being especially satisfied of the fact that the offspring frequently inherited some of their characters from a former mate of the dam, while both English and See also:Continental naturalists (apparently without putting the assertions of breeders to the test of experiment) accounted for the " throwing back " by saying the germ cells of the darn had been directly or indirectly "infected " by a former mate . It is noteworthy that L . See also:Agassiz, C . See also:Darwin, W . B . See also:Carpenter, and G . J . See also:Romanes were all more or less See also:firm believers in the doctrine of infection, and that a few years ago, with the exception of See also:Professor A . See also:Weismann, all the leading biologists had either subscribed to the See also:telegony doctrine or admitted that " infection of the germ " was well within the See also:bounds of possibilities . Even Professor Weismann did not deny the possibility of the offspring throwing back to a previous mate . The widespread belief, he admitted, " may be justifiable and founded on fact," but he was careful to add that " only the See also:confirmation of the tradition by methodical investigation, in this See also:case by experiment, could raise telegony to the See also:rank of a fact." In assuming this attitude Professor Weismann decidedly differed from See also:Herbert See also:Spencer, who some years ago mentioned that he had evidence " enough to prove the fact of a previous sire asserting his See also:influence on a subsequent progeny." The importance of determining whether there is such a thing as telegony is sufficiently evident . If a See also:mare or other See also:female See also:animal is liable to be " infected " by her first or by subsequent mates, telegony will rank as a cause of variation, and breeders will be justified in believing (1) that pure-bred See also:females are liable to be " corrupted " when mated with sires of a different breed; and (2) that inferior or See also:cross-bred females, if first mated with a high-class sire, will thereafter produce See also:superior offspring, how-ever inferior or cross-bred her subsequent mates . If, on the other See also:hand, " infection of the germ " is impossible, telegony will not See also:count as a See also:factor in variation, and breeders will no longer be either justified in regarding mares and other female animals as liable to be " corrupted " by See also:ill-assorted unions, or benefited by first having offspring to a high-class, or it may be more vigorous, mate . Though, according to breeders, evidence of telegony has been found in nearly all the different kinds of domestic mammals and birds, most stress has been laid on instances of " infection " in the See also:horse and See also:dog families . Telegony in the Horse See also:Family.—See also:Beecher at the end of the 17th See also:century pointed out that " when a mare has had a See also:mule by an See also:ass and afterwards a foal by a horse, there are evident marks on the foal of the See also:mother having retained some ideas of her former paramour, the ass." That mares used in mule breeding are liable to be infected is still widely believed, but irrefragable evidence of the influence of the ass persisting, as Agassiz assumed, is conspicuous by its See also:absence . Darwin says, " It is See also:worth See also:notice that farmers in See also:south See also:Brazil . . . are convinced that mares which have once See also:borne mules when subsequently put to horses are extremely liable to produce colts striped like a mule " (Animals and See also:Plants, vol. i. p . 436) . See also:Baron de See also:Parana, on the other hand, says, " I have many relatives and See also:friends who have large establishments for the rearing of mules, where they obtain from 400 to 1000 mules in a See also:year . In all these establishments, after two or three crossings of the mare and ass, the breeders cause the mare to be put to a horse; yet a pure-bred foal has never been produced resembling either an ass or a mule." The prevalence of the belief in telegony at the See also:present See also:day is largely due to a case of supposed infection reported to the Royal Society in 182o by See also:Lord See also:Morton . A See also:chestnut mare, after having a hybrid by a See also:quagga, produced to a See also:black Arabian horse three foals showing a number of stripes—in one more stripes were present than in the quagga hybrid . The more, however, the case so intimately associated with the name of Lord Morton is considered,, the less convincing is the evidence it affords in favour of " infection." Stripes are frequently seen in high-See also:caste Arab horses, and cross-bred colts out of Arab mares sometimes present far more distinct bars across the legs and other See also:zebra-like markings than characterized the subsequent offspring of Lord Morton's seven-eighths Arabian mare . In the absence of See also:control experiments there is therefore no See also:reason for assuming Lord Morton's chestnut mare would have produced less striped offspring had she been mated with the black Arabian before giving See also:birth to a quagga hybrid . To See also:account for the stripes on the subsequent foals, it is only necessary (now that the principles of cross-breeding are better understood) to assume that in the cross-bred chestnut mare there See also:lay latent the characteristics of the Kattiawar or other See also:Indian breeds, in which stripes commonly occur . Darwin and others having regarded Lord Morton's mare as affording very strong evidence in support of the infection hypothesis, it was considered some years ago desirable to repeat Lord Morton's experiment as accurately as possible . The quagga having become See also:extinct, a number of mares were put to a richly striped Burchell zebra, and subsequently bred with Arab, thorough-bred and cross-bred sires . Other mares were used for control experiments . See also:Thirty mares put to a Burchell zebra produced seventeen hybrids, and subsequently twenty pure-bred foals . The mares used for control experiments produced ten pure-bred foals . Unlike Lord Morton's quagga hybrids, all the zebra hybrids were richly, and sometimes very distinctly, striped, some of them having far more stripes than their zebra See also:parent . Of the subsequent foals, three out of Highland mares presented indistinct markings at birth . But as equally distinct markings occurred on two pure-bred Highland foals out of mares which had never seen a zebra, it was impossible to ascribe the stripes on the foals See also:born after zebra hybrids to infection of their respective dams . Further, the subsequent foals afforded no evidence of infection, either in the mane, tail, hoofs or disposition . Of the pure-bred foals, i.e. the foals by pure-bred sires out of mares which had never been mated with a zebra, two were striped at birth and one acquired stripes later—they were revealed as the foal's coat was See also:shed . More-over, while the faint markings on the foals born after hybrids completely disappeared with the foals' coat, the stripes on the three pure-bred colts persisted . One of the permanently striped colts, a See also:bay, was out of a black See also:Shetland mare by a black Shetland sire, one was by a dun See also:Norwegian See also:pony out of a See also:roan-coloured Arab mare, while the third was by a Norwegian pony out of a See also:half-bred bay Arab mare . It has been asserted by believers in telegony that evidence of infection may. appear in the second though not present in the first See also:generation . By way of testing this See also:assumption, a bay filly, the half-See also:sister of a richly striped hybrid, was put to a cross-bred Highland pony, and a Highland mare, while See also:nursing her hybrid foal, was put to a See also:colt the half-brother of a hybrid . The result was two fillies which in no single point either suggest a zebra or a zebra hybrid . Similar results having been obtained with horses and asses, there is no See also:escape from the conclusion that the telegony tradition is not confirmed by such methodical investigations as were suggested some years ago by Professor Weismann (see Eossar See also:Ewart, The Penycuik Experiments, 1899) . Telegony in See also:Dogs.—Breeders of dogs are, if possible, more thoroughly convinced of the fact of telegony than breeders of horses . Nevertheless, See also:Sir See also:Everett See also:Millais, a recognized authority, has boldly asserted that after nearly thirty years' experience, during which he made all sorts of experiments, he had never seen a case of telegony . Recent experiments support Millais's conclusion . Two of the purest breeds at the present day are the Scottish deerhound and the Dalmatian (spotted See also:carriage-dog), A deerhound after having seven pups to a Dalmatian was put to a dog of her own breed . The result was five pups, which have grown into handsome hounds without the remotest See also:suggestion of the previous Dalmatian mate of their dam . A similar result was obtained with a deerhound first mated with a retriever .
Many accidental experiments on telegony are made annually with dogs
.
Two such experiments may be mentioned
.
A black-brindled Scottish terrier belonging to a famous breed had first a See also:litter of pups to a See also:curly-haired See also:liver-and-See also: This belief seems to be especially prevalent amongst breeders of cattle; but how, for example, a See also:long-horned Highland See also:bull, used for See also:crossing with black hornless See also:Galloway cows, could subsequently get Galloway-like calves out of pure Highland heifers it is impossible to imagine . In conclusion, it may be pointed out that it was only natural for breeders and physiologists in bygone days to account for some of their results by the " infection " hypothesis . Even now we know surprisingly little about the causes of variation, and not many years ago it was frequently asserted that there was no such thing as reversion or throwing back to an ancestor . But even were the See also:laws of See also:heredity and variation better under-stood, the fact remains that we know little of the origin of the See also:majority of our domestic animals . On the other hand, from the experiments of Mendel and others, we now know that cross-bred animals and plants may present all the characters of one of their pure-bred parents, and we also know that the offspring of what are regarded as pure-bred parents sometimes revert to remote, it may be quite different, ancestors . The better we understand the laws of heredity and variation, and the more we learn of the See also:history of the germ cells, the less need will there be to seek for explanations from telegony and other like doctrines . (J . C . |
|
|
[back] TELAV |
[next] TELEGRAPH (Gr. Tike, far, and rypaq5eiv, to write) |
There are no comments yet for this article.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.
Links to articles and home page are encouraged.