8 INTRODUCTION, 



the blood-vessels tliat noiirish the feathers. For 

 instance, if a feather is all one tint, it will have 

 only one secreting gland, and one vessel running 

 along the quill, which is afterwards branched out 

 and ramified all over the feather through which 

 the colouring matter is injected; but, if the fea- 

 ther has three colom's, as red, blue, and yellowj 

 then there will be three distinct glands, and ona 

 vessel attached to each gland, for conveying the 

 colouring matter to the feather, and so on in pro- 

 portion to the number of tints in each feather. 



The annual loss and renewal of feathers, at the 

 J)eriod of moulting, is a curious cu'cumstance in 

 the natural liistory of birds ; but not more singu- 

 lar than the shedding and renemng of the horns 

 of a deer, or the casting and reproducing of the 

 shell of a crab. Animals that undergo the pro- 

 cesses of the loss and reproduction of parts, are, 

 during that operation, more or less affected with 

 temporary debility and sickness. In a wild state, 

 nature, it is supposed, carries birds through the 

 operation mtliout injury ; but, in a state of domes- 

 tication, — their natural habits and constitutions 

 having undergone a change, — they require both 

 care and attention at that time. They ought to 

 be kept in a diy, well-aired room, the temperature 



