. The structure and life of birds . asy and dry. What purpose they mayserve is quite uncertain. By the help of these simpler specimens we musttry to realise that the most elaborate feather is onlya much-divided scale. Such a feather I must nowdescribe, and then try to show how it has grown froma skin papilla. Take a large one from the wing ortail of any common bird. The semi-transparent baseis the quill (0, fig. 38) ; it has two small apertures,one at the bottom, the other at the top, where thebranches begin, on the under-surface (U 1 and 2).At the lower one the papilla entered to give the nee
. The structure and life of birds . asy and dry. What purpose they mayserve is quite uncertain. By the help of these simpler specimens we musttry to realise that the most elaborate feather is onlya much-divided scale. Such a feather I must nowdescribe, and then try to show how it has grown froma skin papilla. Take a large one from the wing ortail of any common bird. The semi-transparent baseis the quill (0, fig. 38) ; it has two small apertures,one at the bottom, the other at the top, where thebranches begin, on the under-surface (U 1 and 2).At the lower one the papilla entered to give the need-ful nourishment, and if a young feather be taken, thequill will be found full of blood (P). VI FORM AND FUNCTION 47 When the quill is dry and hollow, the feather isin most ways a dead thing, but the fact that insome birds there is a change of colour without amoult, and without the loss of any part of the feather,shows that it has not entirely lost life. The stiff rodabove the quill is the rachis or shaft (S). It is grooved -v$^§.
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Keywords: ., bookcentury1800, bookdecade1890, bookidstructurelif, bookyear1895
