ANIMAL LIFE AND THE MICROSCOPE 



from a wing. Now, under a higher magnification, 

 we can plainly see the little cells of which the down 

 feather is built up. 



One of the strong wing feathers of such a bird 

 as a pigeon is of the greatest interest as a micro- 

 scopic object. We must take a few of the barbules, 

 the slender, flattened portions of the feather which 

 fringe either side of the barb. A moderately high 

 magnification will show how ingeniously they are 

 contrived. The hinder side of each barbule is a 

 moderately thick upwardly curved edge whilst, on 

 the forward side, there is a row of curved hooks. 

 When the feather is neat and tidy, and its owner 

 when in good health usually sees to it that its 

 feathers are well kept, the hooks of one barbule 

 engage with the curved edge of the next barbule. 

 The feather, by means of this ingenious locking 

 device, becomes much more nearly a solid structure 

 than would be the case if the barbules did not hook 

 on to one another. The arrangement for hooking 

 together the fore and hind wings of bees and wasps 

 is very similar. We may examine a number of 

 flight feathers but we shall not find any very strik- 

 ing differences between those of various birds. All, 

 apparently, follow a common design. 



From feathers to hair and from hair to horns and 

 some scales is not a very far cry. We have talked 

 about the examination of hair in another chapter, 

 so we will not repeat ourselves here. Scales we 

 shall most of us have opportunities of examining in 

 plenty. We have just mentioned that some scales 



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