A FEATHER. 687 



so that it may be bent downward very easily by pressure near the tip, 

 but does not bend so easily the other way. Notice, too, that the shaft 

 is not straight, but bent so that the upper surface of the feather is 

 convex, and the lower concave. We shall soon find a meaning in all 

 these properties. 



Passing now from the shaft to the vane, we see that the two sides 

 are not alike : one edge, or vane — the one on the right-hand side of 

 every feather in the right wing, that is, the side nearest the tip of the 

 spread wing — is short and stiff, while the vane on the other side of the 

 shaft is broad and flexible ; and, by examining the feathers in their 

 places in the wing, we see that the. broad inside edge of the first or 

 outside feather passes under the stiff, narrow outside eCige of the 

 next feather, which has its own inner edge supported in the same 

 way by the third feather, and so on through the wing. When the 

 wing is flapped downward through the air, the broad edge of each 

 feather is pressed against the inflexible narrow edge of the feather 

 next it, and the whole wing is thus made air-tight ; but, when the 

 wing is moved the other way, the broad edges have nothing to sup- 

 port them, and are pressed downward, so that the air can pass be- 

 tween the feathers. 



The vane is also made up of separate pieces. If it is carefully ex- 

 amined, separate pieces, or " barbs," will be seen running off from 

 each side of the shaft at a slight angle, and parallel to each other, 

 united in such a way as to form two flat plates, the vanes. These 

 barbs are fastened to each other quite firmly, but, if part of the vane 

 is pulled down toward the quill, the barbs will separate at last with a 

 tearing sound, and if this is repeated in a few places it will give the 

 feather a very, draggled appearance, and ifc will seem torn beyond pos- 

 sibility of restoration ; but, if it be drawn gently between the fingers two 

 or three times from base to tip, the broken places will unite so per- 

 fectly that it may be quite impossible to find them again. The work- 

 ing of the mechanism by which the attachment is made is so perfect 

 that it need only be noticed to be admired, and careful examination 

 will reveal the simple means by which it is accomplished. 



Each barb, when examined with a lens, is seen to bear some re- 

 semblance to the whole feather ; like the feather, it has a shaft run- 

 ning longitudinally, and a vane on each side of it. These vanes are 

 unequal, as in the whole feather, and they are composed of separate 

 pieces running off from the shaft, and called " barblets," because they 

 are to the barb what the barbs are to the whole feather. On the side 

 of the barb toward the tip of the feather the barblets run out from 

 the shaft of the barb nearly at right angles, and send off from their 

 lower surfaces little hooks at regular intervals, all pointing down- 

 ward ; on the other side of the barb the barblets have no hooks, and, 

 instead of being set at a large angle with the shaft, they are almost 

 parallel with it, so that where they meet and run under the hooked 



