68 
THE FEATHERS. 
appetite ; their eyes become dull, and they betray symptoms 
of weariness and weakness. In some birds tbis growth of 
feathers is always going on ; and they may be said to be in 
a perpetual moult ; while in others again, and those chiefly 
water birds, the process of moulting or changing plumage 
occurs only twice in the year, in autumn and in spring ; 
and here again we shall find that Creative Wisdom is at 
work in acting for the best. 
That there is a great difference in the summer and winter 
plumage of many birds is known to almost everybody ; hut 
it requires a closer examination to see that much of this 
difference consists in a great increase of warmth, to meet 
the severity of the latter season, which is thus produced. 
In the autumnal moult, when the summer feathers fall off, 
the new feathers which take their place will he found to he 
fringed. This fringe is generally of the same texture, though 
almost always of a warmer and more downy character, and 
often of a different colour, which will account for the variety 
of tints often observed in birds at these different seasons of 
the year. As the spring advances these little fringes break 
off, and leave the edge of the feather sharp and defined, hut 
of course shorter ; in this very simple manner is the bird 
divested of a quantity of winter clothing, when the weather 
is warmer, and a superfluity of apparel no longer required. 
In the case of two species of Partridges, called the Wood 
and Rock Partridge of North America, which, in winter, 
burrow underneath the snow, a still warmer covering is 
provided, the growth of feathers being actually doubled; 
so that they have nearly twice as warm a coat, when they 
most require it, as they had during summer, when it was 
unnecessary. 
Generally speaking, the colour of the plumage in different 
species is the same; there are, however, some constant ex- 
ceptions, as, for instance, in the Ruffs and Reeves, in which 
no two birds are ever found exactly alike. The Ptarmigans, 
again, vary considerably; the Cross-beak also has the same 
peculiarity, and it is almost needless to point out the constant 
variety observable in our common barn-door fowls; but, 
