VI 



FORM AND FUNCTION 



45 



rhinoceros. But even with feathers, if we begin with 

 the simplest instead of the most elaborate, the diffi- 

 culty will appear much less, though it may not entirely 

 vanish. A still better plan will be to begin with the 

 scale of a reptile, and show how it corresponds to a 

 bird's feather. The scale proper is formed from the 



Fig. 37. 



(n) Feather of Duck, carrying nestling down feather ; (/>) Nestling down of Thrush; 



(c) of Pigeon ; (d) Thread feather of Goose ; (7>), (c), and (it) after Gadow ; f, Feather 



proper ; N, Nestling down. 



skin, its horny coating from the epidermis. Where a 

 feather is to grow, there is a little skin papilla or 

 pimple, which corresponds to the scale proper ; the 

 actual feather is formed from the epidermis that 

 covers the papilla, and corresponds to the horny 

 covering of the scale. On the wings of the Penguin, 

 or on the legs of birds of the Ostrich kind — e.g., the 



L 



