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Show 170 DOMESTIC PIGEONS. CIIAP. V. wing-feathers is not a character which. is intentiona~ly selected by fanciers ; but fanciers have been trymg for centunes, at least since the year 1600, to increase the length of the reversed feathers on the neck, so that the hood may more completely enclose the head; and it may be suspected that the increased length of the wing and tail-feathers stands in correlation with the increased length of the neck-feathers. Short-faced tumblers have short wings in nearly due proportion with the reduced size of their bodies ; but it is remarkable, seeing that the number of the primary wing-feathers is a constant character in most birds, that these tumblers generally have only nine instead of ten primaries. I have myself observed this in eight birds ; and the Original Columbarian Society 37 reduced the standard for baldhead tumblers from ten to nine white flight-feathers, thinking it unfair that a bird which had only nine feathers should be disqnalified for a prize because it had not ten white flight-feathers. On the other hand, in carriers and runts, which have large bodies and long wings, eleven primary feathers have occasionally been observed. Mr. Tegetmeicr has informed me of a curious and inexplicable case of correlation, namely, that young pigeons of all breeds, which when mature become white, yellow, silver (i.e. extremely pale blue), or dun-coloured, are born almost naked ; whereas other coloured pigeons are born well clothed with down. Mr. Esquilant, however, has observed that young dun carriers are not so bare as young dun barbs and tumblers. Mr. Tegetmeier bas seen two young birds in tho same nest, produced from differently coloured parents, which differed greatly in the degree to which they were at first clothed with down. I have observed another case of correlation which at first sight appears quite inexplicable, but on which, as we shall see in a future chapter, some light can be thrown by the law of homologous parts varying in the same manner. The case is, that, when the feet arc much feathered, the roots of the feathers are connected by a web of skin, and apparently in correlation with this the two outer toes become connected for a considerable space by skin. I have observed this in very many 3 ' J. M. Eaton's 'frcatise, edit. 1858, p. 78. CrrAP. V. ON THE EFFECTS OF DISUSE. 171 specimens of pouters, trumpeters, r:;wallows, roll~r-tumblers (likewise observed in this breed by Mr. Brent), and m a lesser degree in other feather-footed pigeons. The feet of the smaller and larger breeds are of course much smaller or larger than those of the rock-pigeon; but the scutellro or scales covering the toes and tarsi have not only decreased or increased in size, but likewise in number. To give a single instance, I have counted eight scutellre on the hind toe of a runt, and onl' five on that of a short-faced tumbler. With Lirds in a state of natme the number of the scutellre on the feet is usually a constant character. The length of the feet and the lenath of the beak apparently stand in correlation; but as dis~so apparently has affected the size of the feet, this case may ~omo under the following discussion. On tlte Effects of IJisuse.-In the following discussion on the relative proportions of the feet, stemum, furcula, scapulre, and wings, I may premise, in order to give some confidence to the reader, that my measurements were all made in the same manner, and that all the measurements of the external parts were made without the least intention of applying them to the following purpose. I measured most of the birds which came into my possession, from the feathered base of the beak (the length of beak itself being so variable) to the end of tho t:'til, and to the oil-gland, but unfortunately ( oxcopt in a few cases) not to tho root of tho tail; I measured each bird from the extreme tip to tip of wing; and tho length of the terminal folded part of tho wing, from tho extremity of tho primaries to tho joint of tho radius. I measured the feot without the claws, from tho end of the middle too to tho ond of tho hind toe; and the tarsus together with tho middle too. I havo taken in every case tho moan measurement of two wild rock-pigeons from tho Shetland Islands, as tho standard of comparison. The following table shows tho actual length of tho feet in each bird; and the clifforonce between tho length which tho foot ought to have had according to tho size of body of each, in comparison with tho sizo of body ancl length of foot of tho r0ck-pigcon, calculated (with a fow specified exceptions) by the standard of tho length of tho body from tho baso of tho beak to tho oil-gland. I have proforrod this standard, owing to tho variability of tho length of tail. Dut I have made similar calculations, taking as the standard tho length from tip to tip of wing, and likewise in most cases from the base of the beak to the end of the t:'til; and tho result has always been closely similar. To givo an example: tho first bird in the table, being a short-faced tumbler, |