14 INTKODUCTION. 



the ostrich there is none ; in some birds it is a mere tuft at 

 the origin of the webs, in others it is a second feather ori- 

 ginating there ; and there are all the intermediate states in 

 different birds, and very considerable seasonal differences in 

 the same bird. 



Different birds find their food in different states, both of 

 the atmosphere and the waters; and very beautiful corre- 

 sponding differences in their plumage may be traced. The 

 plumage upon the raven, which braves the storm in the wilds, 

 is very different from that of the gallinaceous or poultry races 

 which a slight shower drives to their cover or their perch ; 

 and ducks and other water-birds, which seek their food peace- 

 ably on the banks or by swimming in the shallow waters, 

 have very different plumage from those which hawk about on 

 the wing in order to catch what the troubled sea brings to 

 the surface. If the habit of the bird be to steal softly on its 

 prey, then the feathers are fined off to exceedingly delicate 

 points, so that it can glide silently through the air. 



MOULT AND MIGRATION. 



The feathers of birds, while they remain perfect and firm 

 in their connection, are really parts of a living animal, and 

 as such they must be regarded as organs of feeling. They do 

 not probably in themselves feel pain, but they are in intimate 

 connection with parts which do. The epidermis in no animal 

 appears to feel pain, even in those parts of the animal which 

 are regarded as being more immediately the organs of sensa- 

 tion ; but they very speedily transmit impressions to the 

 parts that do feel. It is the same with hair, and with all the 

 appendages of the cuticle, such as nails, claws, hoofs, and 

 horns. The horse feels his footsteps in the dark, even when 

 his hoofs are shod with iron ; and he feels not only the touch 

 of a wall, a gate, or any other obstacle, but he feels the differ- 



