Rachis | feather part | Britannica (original) (raw)

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structure

• 
  In feather
  …of a central shaft (rachis), with serial paired branches (barbs) forming a flattened, usually curved surface—the vane. The barbs possess further branches —the barbules—and the barbules of adjacent barbs are attached to one another by hooks, stiffening the vane. In many birds, some or all of the feathers lack…
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• 
  In bird: Feathers
  …a tapered central shaft, the rachis, with paired branches (barbs) on each side. An unbranched basal section of the rachis is called the calamus, part of which lies beneath the skin. The barbs, in turn, have branches, the barbules. The barbules on the distal side of each barb have hooks…
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