Introduction 



In some birds, as in the Cassowaries and Emeus, the aftershaft is as large as, or 

 larger than, the main portion of the feather, while in others it is greatly reduced 

 or even absent. 



Not all feathers exhibit as complicated a structure as that above described. 

 In many cases the feather is much reduced, as for example in the wing-quill of 

 the Cassowary, which consists merely of the stiff, naked stem or rachis. The 

 so-called filo plume is another modification of the typical feather, a good example 

 of which may be seen on the body of a common fowl after the removal of the 

 outer or contour feathers It is to all appearances a slender hair, but in reality 

 it is a degenerate feather which has a very short barrel and a thin, hair-like rachis 

 with few or no branches. Usually the filoplumes are entirely concealed by the 



contour feathers, although in some birds, 

 as the Cormorants, they form tufts of 

 plumes on the sides and back of the 

 neck which project beyond the outer 

 (contour) feathers. A further modifica- 

 tion is found in the so-called "downs," 

 these being feathers in which there is 

 no rachis, the long fluffy branches all 

 arising at the top of the barrel: they 

 are concealed by the contour feathers. 

 In certain birds, such, for example, as 

 the Herons, Bitterns, some Hawks, Par- 

 rots, Tinamous, etc., the downs are 

 aggregated in special patches, called 

 " powder-downs," in which the ends are 

 continually breaking off into fine, dust- 

 like particles. In the Herons, for in- 

 stance, the powder-downs form enormous patches, a pair on the breast and 

 a pair over the thighs. Their nature is not well understood, although their 

 presence may constitute a well-marked character for descriptive purposes. 



Colors of Feathers. The colors of feathers, or their apparent colors, constitute 

 an exceedingly interesting phase of this subject. In accordance with the latest 

 authorities the colors of feathers may be conveniently classed under three heads. 

 The first of these, and the most general, are called chemical or absorption colors, 

 since they are due to the presence of distinct coloring-matter. This coloring- 

 matter may be in the form of a pigment, or may be a coloring solution, which is 

 distributed in or among the cells composing the various parts of the feathers. 

 Under this category come black, red, and brown, mostly the orange and yellow, 

 but rarely green, and never blue. These colors may be recognized by the fact 

 that they do not change under any condition of illumination or the position of the 

 eye viewing them, and certain of them, as black, red, and yellow, may be separated 

 in a practically pure state by well-known methods of chemical manipulation. 

 One of the most interesting, known as turacin, is found in the red feathers of the 

 Plantain Eaters (Musophagida). It contains the same chemical elements as 



FIG. i. Feather and aftershaft. 



