20 



The Bird 



A list of all the structures of animals which are prod- 

 ucts of the outer layer alone would be a long and sur- 

 prising one, and we would be very ready to grant the 

 importance of skin. Such an enumeration would include 

 all claws and talons, nails and teeth, the rattles of a 

 snake, spurs, hairs, the scales of fishes and reptiles, 



\\ 



FIG. 9. Tarpon-scale, shark-tooth, and peacock-feather; showing diversity of 

 structure derived from the skin alone. 1/2 natural size. 



spines, whalebone, beaks and feathers. Even the horn 

 of a rhinocerus is only a solid mass of agglutinated 

 hairs, while as the antithesis to this may be mentioned 

 all down and feathers : the tiniest fluff from a humming- 

 bird to the great pinion of a condor. 



If we examine a newly hatched dove or sparrow, 

 the little, ugly, sprawling creature, at first glance, seems 



