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die, a series of little filaments will be noticed to cause this resistance. 

 These filaments are the barbules, and it is by their locking one into 

 the other that the great strength of the wing-feather is maintained. 

 And of the many wonderful contrivances presented to us in Nature, 

 none can exceed in beauty and simplicity of mechanism the structure 

 in question. 



In the wings of most of the Hymenoptera we have an analogous de- 

 velopment of little hooks or barbules from the anterior superior mar- 

 gin of the second pair of wings. These, in the expanded state of the 

 wings, are attached to a little fold on the lower margin of the first 

 wing, and by this means serve to unite the two wings into one, so that 

 greater strength is given to them, whereby the act of flight can be 

 more rapidly accomplished. Another analogous use of hooks or bar- 

 bules is presented to us in the lower part of the hairs of the common 

 mole. The hairs of these animals, it may not be generally known, will 

 lie quite smooth whether the skin be rubbed from the tail towards the 

 head, or from the head towards the tail. Some of the hairs being 

 much thicker and broader towards the free extremity than in any 

 other part, the lower portion acts as a species of hinge on which the 

 upper part can turn in any direction, whilst the lower gets its strength 

 by holding on to its neighbours by its barbules, which are in some 

 cases largely developed. 



The feathers of birds which depend on flight as a means for their 

 subsistence, are constructed nearly on the same plan ; but there are 

 others which are to be found on such birds as have no power of flying 

 whatever. Amongst them may be mentioned the ostrich, cassowary, 

 emeu and apteryx. If a feather be taken from the rudimentary wings 

 of any one of these creatures, it will be found to differ greatly from 

 the wing-feathers before alluded to. The barbs are very far apart, 

 the barbules are largely developed, they are straight, and do not hook 

 into those of the adjoining barbs, but hang quite loose and separate 

 from one another, forming only a kind of down, so that however beau- 

 tiful and ornamental such feathers may be to fit them for the flowing 

 honours of a lady's head-dress, it is actually their want of development 

 that makes them so highly prized. 



But the principal modifications found in the wing-feathers of birds 

 generally, are carried out to their fullest extent in the feathers of the 

 owl tribe. If a wing or tail feather be taken from a bird of this kind 

 and carefully examined, it will be found that besides the fastening 

 together of the individual barbs by means of the barbules, there is an 

 additional series of filaments developed from the sides of the barbules 



