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M0ffO&% 



COLOR AND STRUCTURE OF PLUMAGE 83 



extends. The lower portion of the quill is fastened in the skin. It 

 is like the root of a hair, serving as an anchor, holding the feather 

 in its place. But the feather itself is unlike a hair which is constantly 

 growing, for once the feather is grown, the pulp in the quill and 

 shaft becomes pith, and no further nourishment is extended by the 

 body. If you cut the quill with your pen knife, you find a series of 

 hollow, oblong cells fitting into 

 one another. These cells are 

 now shriveled, but during 

 growth they contained the nut- 

 rient matter from which the 

 feather was built up. 



The web presents the appear- 

 ance of a smooth surface, groov- 

 ed with a number of fine parallel 

 lines. If we place this web 

 under a lens that raises its size Feather From Back Section of Hen 

 twenty times, we behold a woven 



fabric! We find that the grooved appearances are caused by inter- 

 spaces between the ribs or barbs which extend out from the shaft. 



Again we look at the feather under the microscope and we see 

 these interspaces are filled with the intercrossing of fine hair-like 

 barbules. We study longer and find the barbules are all hooked 

 together. Split the web; it doesn't give apart readily at first, but a 

 little pressure and the booklets give; gently stroke it back into place 

 and the booklets on the barbules go into place and hold the barbs 

 together. 



About all we can see unaided by the microscope are the barbs; 

 the rest of the links are finer than the senses of either sight or touch. 

 In fact, the network is fitted together so closely and so perfectly that 

 air cannot force its way through the feather. 



The wonder of nature does not stop here. She deposits color pig- 

 ment in these numberless parts of the feather with a definite regu- 

 larity and percision that beggars description. We see the barring of 

 white and dark, sharply defined, or a white feather with a black band 

 around its outer border, or a red feather marked with three distinct, 

 concentric lines of black, one hand within another. If we take the 

 barred feather, we find one barb has four visible bars of dark color 

 and ends with dark, another has four bars of dark but they are 

 not located the same, so the barb ends with white; and it is the exact 

 position of one barb to another that makes the dark bar extend 

 straight across the feather. These lines of barring that we admire 

 are therefore "not continuous, not organically complete, but formed 

 by the exact relation, one to another, of a series of minute spots of 

 pigment, each lodged in a separate filament, so that the several spots 

 in each filament, when ranged side by side, form the several series 

 of lines or bars." 



