« FöregåendeFortsätt »
study and a field of observation. Insignificant, and to us valueless wild animals, brought from a distance, about whose history and habits we can learn little or nothing, are received with respectful attention by men of education and ability, are embalmed in spirits, treasured in museums, and pourtrayed by artists ; but a class of creatures inferior to few on the face of the earth in beauty, useful, companionable, of great value in an economical point of view, are disregarded and disdained. It is possible that any one claiming to be considered as an educated gentleman, may be thought to have done a bold thing in publishing a book on Poultry, and giving his real name on the title page. Moubray, who has written perhaps the best modern treatise on the subject, only ventured to meet the public criticism under the shelter of an assumed title.
But some very important speculations respecting organic life, and the history of the animated races now inhabiting this planet, are closely comected with the creatures we retain in Domestication, and can scarcely be studied so well in any other field. Poultry, living under our very roof, and by the rapid succession of their generations, affording a sufficient number of instances for even the short life of man to give time to take some cognisance of their progressive succession, - Poultry afford the best possible subjects for observing the transmission or interruption of hereditary forms and instincts.
I shall, no doubt, at the first glance, be pronounced rash, as soon as I am perceived to quit the plain task of observing, for the more adventurous one of speculating upon what I have observed. I can only say that the conclusion to which I have arrived respecting what is called the “ origin ” of our domestic races, has been, to my own mind, irresistible, having begun the investigation with a bias towards what I must call the wild theory, although so fashionable of late, that our tame breeds or varieties are the result of cross breeding between undomesticated animals, fertile inter se. It will be found, I imagine, on strict inquiry, that the most careful breeding will only fix and make prominent certain peculiar features or points that are observed in certain families of the same aboriginal species, or sub-species,—no more: and that the whole world might be challenged to bring evidence (such as would be admitted in an English court of justice) that any permanent intermediate variety of bird or animal, that would continue to reproduce offspring like itself, and not reverting to either original type, have been originated by the crossing of any two wild species. Very numerous instances of the failure of such experimental attempts might be adduced. The difficulty under which science labours in pursuing this inquiry, is much increased by the mystery in which almost all breeders have involved their proceedings, even if they have not purposely misled those who have endeavoured to trace the means employed.
As to the great question of the Immutability of Species, so closely allied to the investigation of the different varieties of Poultry, as far as my own limited researches have gone—and they have been confined almost entirely to Birds under the influence of man—they have led me to the conclusion that even sub-species and varieties are much more permanent, independent, and ancient, than is currently believed at the present day. This result has been to me unavoidable, as well as unexpected; for, as above mentioned, I started with a great idea of the powerful transmuting influence of time, changed climate, and increased food. My present conviction is that the diversities which we see in even the most nearly allied species of birds, are not produced by any such influences, nor by hybridisation ; but that each distinct species, however nearly resembling any other, has been produced by a Creative Power: I am even disposed to adopt this view towards many forms that are usually considered as mere varieties. As far as I have been able to ascertain facts, hybrids that are fertile are even then saved from being posterityless (to coin a word) only by their progeny rapidly reverting to the type of one parent or the other : so that no intermediate race is founded. Things very soon go on as they went before, or they cease to go on at all. This is the case with varieties also, and is well known to breeders as one of the most inflexible difficulties they have to contend with, called by them “crying back.” This circumstance first led me to suspect the permanence and antiquity of varieties, and even of what are called “improvements” and “new breeds." Half of the mongrels that one sees are only transition-forms, passing back to the type of one or other original progenitor. At least, my own eye can detect such to be frequently the apparent fact in the case of Domestic Fowls. Any analogies from plants must be cautiously applied to animals ; but even in the vegetable kingdom the number and reproductive power of hybrids is apparently greater than it really is, owing to the facility of propagation by extension, by which means a perfectly sterile individual can be multiplied and kept in existence for many hundred years ; whereas a half-bred bird or animal would, in a short time, disappear, and leave no trace. I have not met with one authenticated fact of the race of Pheasants having been really and permanently incorporated with Fowls, so as to originate a mixed race capable of continuation with itself; but with many that prove the extreme improbability of such a thing happening. The vulgar notions, that Hens kept at the sides of plantations therefore become the mothers of half-bred chickens, by whom Pheasant blood is again transmitted to their progeny; and that Hens, whose plumage in some measure resembles that of the Cock Pheasant, are therefore hybrid individuals—are too vague to be listened to, in the absence of clearer evidence, which is not yet forthcoming. But it will not be easy to eradicate this prejudice from the popular mind. Mr. Darwin's discovery, the result of his great industry and experience, that “the reproductive system seems far more sensitive to any changes in external conditions, than any other part of the living economy,” confirms my suspicion of the extreme improbability of the origination of any permanent, intermediate, reproductive breed by hybridising. It would thus seem, that so far as those organs are not much changed from their normal condition in one or other parent, (which we may suppose shown by the fact of their producing young resembling, not themselves, but their own parents,) they are fertile ; but, when so changed as to be incapable of producing such young, they do not produce at all. At least, this is the way in which I must interpret the fact. The dissection of a fertile hybrid, and the comparison of its reproductive system with that of either parent, might throw light upon the question ; but it would be a nice undertaking. Mr. Darwin suggests, “ If you ever had it in your power fairly to test the possible fertility of the half-and-half birds inter se, I certainly think you would confer a real service on Natural History.” I have therefore proposed to myself to test the fertility of various halfbred Geese, one with another, avoiding as far as possible near relations, and confining myself to that genus especially, because almost any species of Goose will breed with any other. Geese, therefore, give greater promise of instructive if not successful experiments by the intermarriage of hybrids, than any other bird with which we are acquainted. If my suspicion be correct, that many varieties of Fowls (and perhaps of Dogs) are aboriginal, and not the results of Domestication, the mere fertility of hybrids (partial or complete) must cease to be a test between species and varieties. That, however, is a question of words, rather than of things. It may be observed that a sufficient number of lusus and hybrids have been produced, in the course of ages, to stock the world with an infinite variety of forms, had not that class of heterogeneous beings been in themselves of an unprolific and transitory nature. But the number of existing forms is diminishing instead of increasing. It is not too much to say, that if the history of the world goes on as it now does, every fifty years, for some time to come, will witness the extermination of