xxvi INTRODUCTION ^^ 



Hawks and Parrots. In the Herons and Bitterns 

 they form large patches, a pair on the breast, and a 

 patch over each thigh. Of a pecuhar woolly appear- 

 ance, they are remarkable for the fact that they break 

 up, when touched, into a fine powder, which, when 

 rubbed between the fingers, gives an indescribably 

 smooth feeling. It is the powder from these remark- 

 able feathers which gives the peculiar bloom to the 

 beak of many parrots, as well as to the plumage. As 

 to the real purpose of the powder, however, we know 

 nothing. 



This brief survey of feathers would not be complete 

 without a few words as to their structural characters. 

 In the typical feather (say, a quill-feather) , two main 

 parts are to be distinguished — the stiff stem, and the 

 broad, flexible blade known as the vane, or vexillum. 

 The stem may further be divided into the quill, or 

 calamus, the hollow part below the vane, and the shaft 

 or rhachis, which is flattened in section and filled 

 with a white pith-like substance. The vane runs 

 along on either side of the rhachis in the form of a 

 series of tapering, flattened rods, the "barbs." They 

 are set so closely together that they must be carefully 

 sought for; and give to the vane that finely grooved 

 appearance, or, rather, the appearance of a series of 

 fine lines running obliquely outwards from the shaft. 

 If an attempt be made to pull these apart, it will be 

 found that considerable force must be used, and 

 this is owing to the fact that they are locked together 

 by a second series of flattened rods, known as barbules, 

 so small as to require the microscope to reveal them. 



