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Show 272 FOWLS. CIIAP. VII. In tho eight first birds, belonging to distinct breeds, in t~s table, we soc a decided reduction in tho weight of tho bones of tho wmg. In tho Indian Fri7.zlod fowl, which cannot fly, tho reduction is carried to tho gr atest extent, namely, to thirty-three per cont. of ~heir propm: pr?p?rtional weight. In tl1o next four birds, including tho SJlk-hon, which_Js illca]): tblo of flight, we sec that tho wings, relatively to ~he_ logs, are ~bghtly increased in weight; but it should be observed that, 1f ~n those bJ~ds the Jog.· hacl become from any cause reduced in wc~ght, th:s wo?:ld g1vo :rthe fal. ·o appearance of tho wings having increased ~ relative w01ght. Now a r duction of this nature has certainly occurred w1th tho Burmese Jumper, in which tlto logs arc abnormally short, and in tho. two Hamburg~s and Silk fowl, tho legs, though not short, arc formed of remarkably ~hill n,nd light bonos. I make those statements, not judging by mo.ro oyos1ght, but after having calcnlatocl tho weights of tho log-bonos rolat1vel~ to tbo~o of G. bnnlcivn, according to tho only two standards of companson which I could use, namely, tho relative lengths of tho head and sternum; for I do not know tho weight of tho body in G. bcwlciva, which would h~vo been a bettor standard. According to these stanclards, tho log-bones m these fom fowls arc in a marked manner far lighter than in any other breed. It may therefore be concluded that in all ca. es in which tho logs have not boon tltrongh some unknown cause much reduced in weight, the wing-bones have become reduced in weight relatively to tho log-bones, in comparison with those of 0. bu11lcivn. And this reduction of weight may, I appre-hend, s::tfoly be attributed to disuse. . To make tho foregoing t::tblo quite satisf::tctory, it ought to have been shown that in tho eight first birds tho log-bones h::tvo not actually increased in weight out of duo proportion with tho rest of tho body; this I cannot show, from not knowing, as already remarked, the weight of the wild BankivaJ'1 I am indeed inclined to suspect that tho leg-bones in tho Dorking, No. 2 in tho table, arc proportionally too heavy; but this bird was a very largo one, weighing 7 lb. 2 oz., though very thin. Its leg-bonos wore more than ten times as heavy as those of the Burmese Jumper! I tried to ascertain the length both of the leg-bonos and wingbones relatively to other parts of tho body and skeleton ; but tho whole organi ation in these birds, which have boon so long domesticated, has become so variable, tbat no certain conclusions could be reached. For justanco, tho logs of tho above Dorking cock were nearly three-quarters of an inch too short relatively to the length of tho sternum, and more than in Dorkings as 557 : 24.8, or as 100 : 44; and so on for tho other broods. W o thus got tho series of G2, 52, 44 for tho relative weights of tho wing-bones in G: banlciva, Cochins, Dorkings, &c. And now taking 100, instead of 62, for tho weight of tho wing-bonos in G. banlciva, we get, by another rule of throe, 83 as tho weight of the wing-bonos in Coohins; 70 in the Dorkingf.l; and so on for the remainder of tho third column in the table. 74 1\'lr. Blyth (in 'Annals and Mag. of Nat. Hist.,' 2nd series, vol. i., 1848, p. 456) giv s 3! lb. as tho weight ofafullgrown male G. banlciva; but from what I have seen of the skins and skeletons of various breeds, I cannot believe that my two specimens of G. banlciva conltl have weighed so much. CIIAP. Vll. THE EFFECTS OF DISUSE. 273 ~hree-quar_ters o~ an inch too long relatively to the length of the skull, ill COmpal'lSOn Wlth these same parts in (), ba'ltJciva. In th~ following Table IT. in the two first columns we see in inches and doCim~ls tho length of tho sternum, and the extreme depth of its crest to which tho pectoral muscles aro attached. In the third column we have the. calculate~ dept~ of the crest, relatively to the length of the sternum, ill companson w1th these same parts in G. banlciva.7s ~ames of Breeds. Grtllns brwkiva .. Uochin .. 2 Dorking .. .. 3 Sprtnish 4 Polish .. 5 Game G I M"l'y :: :: .. .. 7 Sultan .. . . .. 8 Frir.zled hen .. !) Burmese Jump~~- .. 10 IIamburgh .. .. 11 Hamburgh .. 12 Silk fowl .. .. TABLE II. mnJo malo malo malo malo malo female male malo female male female female l.cnglh or Sternum. lm·hes. 4•20 5·83 G·95 6•10 5•07 5•55 5·10 4·47 4·25 3·06 5·08 4·55 4·4!) Depth of Crest of Sternum. Jn cbe~. 1•40 1·55 1-!)7 l·8H 1•50 ] •55 1•50 l·3G 1•20 0·85 1•40 1·2G 1•01 D pth of Crest, relatively to the length of the Sternum, In compa· Ison with G. bunklvu. 100 78 84 90 87 81 87 DO 84 81 81 81 66 By looking to the third column we seo that in every case the depth of the cres_t r~lat~ve~y. to the length of the sternum, in comparison with G. b.anlcwn, JS du~nmsho?-, generally between 10 and 20 per cent. But the de~reo of reductiOn vanes much, partly in consequence of the frequent! ~~formed state of tho sternum. In tho Silk-fowl, which cannot fly, the cre?t JS 34 per ?ont. loss deep than what it ought to have been. This reduction of ~ho crest m ~ll the breeds probably accounts for the great variability, before referre~ to, ill tho curvature of the furcula, and in the shape of its sternal extrermty. Medical men believe that the abnormal form of the spine commonly obse~ved in women of tho hjgher mnks results from the attach:~ muscles not. bemg fully exercised. So it is with our domestic fowls, for they ~se therr pectoral muscles but little, and, out of twenty-five sternums ~xammed by me, three alone were perfectly symmetrical, ten were mode-ately crooked, and twelve were deformed to an extreme degree. Finally, we may conclude with respect to the various breeds of the fowl, tha~ the main bones of the wing have probably been shortened m a very slight degree; that they have cer- 75 . Ther third co1 u mn I·S calculated on the same principle as explained in the prevwus tOOt-note, p. 271. VOL. I. T |