HAIRS, FEATHERS, AND SCALES 



29 



backward. Now, whenever the primary beards are brought 

 into contact, some of these hooks catch on the barbule next 

 above, and, slipping into the angles formed by the barbu- 

 lets, hold there, and thus the two contiguous beards are 

 firmly locked together. 



In the beard of the goose-quill, the structure is essen- 

 tially the same, but the barbulets are far more numerous 

 and more closely set; they are also proportionally much 



BARB OF CLOTHING-FEATHER OP FOWL. 



BARB FROM GOOSE-QUILL. 



larger both those which are hooked and those which are 

 simple. Indeed, the latter manifest a tendency to the 

 hooked form, and by all these peculiarities the interlock- 

 ing power is augmented. It is interesting to observe the 

 great dilatation of the beard in a direction toward the infe- 

 rior surface of the feather toward the stroke, as I just now 

 observed. This is to increase the resisting power, as a thin 

 board set edgewise will bear a great weight without bending 

 or breaking, provided it can be kept from yielding laterally, 



