16 



ETEXIXGS AT THE ^nCEOSCOPE. 



of a quill when Ave make u pen, is the medullary portion, 

 dried. There is a beautiful contrivance in the barbs of 

 most featliers, wliicli I will illustrate bj this feather 

 from the body-plumage of the domestic fowl. Every 

 one must have observed the regular arrangement of the 

 vane of a feather, and the exquisite manner in which 



'^ tlie beards of which it is coni- 

 jL posed are connected together. 

 This is specially observable in 

 the wing-feathers, — a goose-quill, 

 for example ; where the vane, 

 though very light and thin, forms 

 an exceedingly firm resistinjr 

 medium, the individual beards 

 maintaining their union with 

 great tenacity, and resuming it 

 immediately, when they have 

 been violently separated. 



JSTow this property is of high 

 importance in the economy of 

 the bird. It is essential that 

 with great lightness and buoy- 

 ancy — for the bird is a jlying 

 creature — there be power to strike tlie air with a broad 

 resisting surface. The wide vanes of the quill-feathers 

 afford these two requisites, strength and lightness ; the 

 latter depending on the material employed, wliich is 

 very cellular, and the former on the mode in which the 

 individual barbs, set edgewise to the direction of the 

 stroke, take a firm hold on each other. 



Xow, in the body-feather which is under the micro- 

 scope, we see that the central stem carries on each side 

 a row of barbs, which interlock Avith each other. The 



BAKB 0» n.OTIIING-FEATHEE 

 OF KOWJ,. 



