ANATOMY OF A QUILL. 397 



of the quill, which is occupied by a number of 

 little, delicate, and membranous pieces of a conical 

 shape, fitting into each other. The quill, we 

 need scarcely say, is that part of the feather 

 which is employed for the purposes of penmanship, 

 and by the help of which greater things have been 

 done than by all the mechanical apparatus ever 

 invented by man. The shaft differs in shape 

 from the quill, being somewhat quadrilateral, or 

 four-sided. It is not hollow like the quill, but 

 contains, within a horny external case, a quantity 

 of a white elastic soft substance called the pith. 

 The vane, however, is the feather's most curious 

 and interesting part. Here we find a most in- 

 genious arrangement of its delicate structure, by 

 means of which that degree of resistance to the 

 air is offered which is necessary to the action of 

 flight. If we take a common quill, and attempt 

 to separate the barbs of the vane from each 

 other, we shall find that they stick together some- 

 what tenaciously, as if they were, in fact, hooked 

 together. Such is actually the case, as can be 

 readily perceived by the assistance of a good lens, 

 or as may be rendered evident by examining the 

 following diagram. The barbs are thin, but stiff 



