HAIRS, FEATHERS, AXD SCALES. 



10 



tlirougli tlie water, produces tlie very same effect as if 

 these fluids were in uiotion and the animals were still ; 

 and therefore the bodies of the latter are, as it were, 

 tiled with feathers or scales, the free edges of which, 

 looking in the opposite direction to the coming of the 

 current (that is, the same direction as its flow), deposit 

 the successive particles of the moving fluid in the midst 

 of the successive feathers or scales. Thus two results 

 ensue, both essential to the comfort of the animal : first, 

 the air or water does not run npward between the 

 feathers or scales to the skin ; and secondly, the surface 

 presents no impediment to free motion. This latter 

 advantage will be appreciated, if you take hold of a 

 dead bird by the legs, and push it rapidly through the 

 air tail-foremost : the feathers will instantly rise and 

 ruffle up, presenting a powerful resistance to movement 

 in that direction. 



These scales of the Perch have their hinder, or free 

 edge, set with fine crystalline points, arranged in suc- 

 cessive rows, and overlapping. Their front side is cut 



''■^^«a^r' 



5CAI.E3 OF pr.ncn. 



with a scolloped pattern, the extremities of undulations 

 of the surface that radiate from a common point behind 

 the centre. These undulations are separated by narrow 



