XXIV 
INTRODUCTION. 
warmer clothing for the winter, nature has endued it with the property of 
changing its vesture. Her benefits are sometimes attended with alloy. The 
nascent plumage absorbs so much of the animal juices as to impair the 
strength of all, tame the ferocity of the rapacious, and even destroy many 
weak individuals. Under the management of skilful persons the moulting 
season is accelerated. The bird is confined in an excessively hot tempe- 
rature in a dark place, and a preternatural fever is induced ; but as this 
premature operation is severe, it frequently destroys the life of the object 
of its care. In moulting, a thin case, or tube, of a quill-like substance, 
formed of layers, is at first protruded from the skin, and in which the 
feather is enclosed. This tube contains a thick, gelatinous liquor, which 
is of a different colour in different parts of the bird. This appears to be 
the colouring matter that gives the hue to the incipient feather, and not 
that which feeds its growth. We have discovered it in some of the fea- 
thers of the Large Titmouse, of a bright yellow in these tubes ; in others, 
of a lead colour, inclining to black. In the Tawny Owl, the Jay, and 
the Kingfisher, we have seen it of a light brown ; and in the common 
fowl, of a rufous colour ; but in birds in general, it is of the dark hue 
before described. Indeed, in the same tube, we have remarked a yellow, 
or a brown liquor, and this lead colour tint together. But this is readily 
accounted for, as the downy parts of the feathers of most of the race wear 
a similar livery, a deep ash-colour hue, to absorb and retain the heat. The 
top of the vane soon thrusts itself out at the outer orifice of the tube, 
appearing like the hair-pencil of the painter. The shaft, which at first is 
very soft and flaccid, and of a jelly-like substance, lies in this tube; it 
soon indurates and increases to its common size, and roots itself in a kind 
of periosteum, or stiff tubular membrane on the surface of the body of 
the bird, through the opening of the nearer end of the tube. By expan- 
sion, the shaft gradually bursts the case which enfolds it, and it falls off in 
a manner not unlike the pod, or outward covering of the seeds of various 
vegetables ; indeed, the whole of this process bears some analogy to that 
of vegetation ; the shaft representing the stem, and the vane the leaf. In 
