. The bird, its form and function . )oint of interest is that the birdsthemselves voluntarily produce the racket condition. Eventhe 3^oungest birds, of both sexes, when the long central Tails 425 tail-feathers have grown beyond the others, instinct i^•elybegin to pick at the vane, soon denuding the shaft sosymmetrically that the rackets are equal in size. The. Fig. 341.—Motmot swinging its tail. photographs show this perfectly. Figure a is the tailof a 3oung male where the operation of ornamental de-nudation has jtist begun; while h shows the conditionin an adult female. The photograph of the
. The bird, its form and function . )oint of interest is that the birdsthemselves voluntarily produce the racket condition. Eventhe 3^oungest birds, of both sexes, when the long central Tails 425 tail-feathers have grown beyond the others, instinct i^•elybegin to pick at the vane, soon denuding the shaft sosymmetrically that the rackets are equal in size. The. Fig. 341.—Motmot swinging its tail. photographs show this perfectly. Figure a is the tailof a 3oung male where the operation of ornamental de-nudation has jtist begun; while h shows the conditionin an adult female. The photograph of the entire liv-ing bird also shows the rackets, as well as the pecuHarpendulum motion of the tail from side to side, although 426 The Bird the motion is more abiii})t than is the motion of a pendu-lum. The Mexican motmot is brilliantly coloured, yet in adensely foliaged tree, among the bright spots of sunlight,it becomes almost in\isible. It is the motion of the tailwhich most often betrays the bird. In the tail marked a in I^ig. 340 it will be noticed that,where the barbs have not yet been ]:)icked off, the unmu-tilated vane is considerably narrowed—an interesting factfor the consideration of evolutionists, as it offers strongcircumstantial evidence, but l)y no means absolute proof,of a case of the inheritance of acquired characters, a much-n ooted cj
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Keywords: ., bookauthorbeebewil, bookcentury1900, bookdecade1900, bookyear1906
