274 
Mr. Yarrell on the 
the brighter tints of others, called by French authors plumage 
des noces , do not make their appearance till the sexual organs 
begin to dilate under the genial influence of spring. 
The various songsters pour forth their constant and most 
melodious strains only during the season of producing and 
rearing their young ; and some birds, as the cuckoo, quail, 
&c. appear capable of exercising their voice but for a limited 
time, confined to the same period of the year. With the 
decline of summer the sexual organs again contract, the 
voice subsides, and the plumage losing its brilliancy, assumes 
by degrees more valuable shades of grey and white for 
defence during the rigour of winter. 
Returning again to the subject of hen-pheasants that are 
said to exhibit the feathers of the cock, it may be stated 
generally, that at best it is but an approximation to the 
plumage of the male. 
It is probable that they do not live many years after the 
commencement of the change, since so few are found to 
arrive at any great degree of splendour. Of the many I have 
had opportunities of examining, none possessed either the full- 
sized broad scarlet patch round the eye, the fine blue zone at 
the end of the red feathers of the breast, or much of the 
bright straw-coloured mark on the scapulars and wing- 
coverts, one specimen alone excepted ; nor have I seen a 
female pheasant with spurs ; and a bird belonging to Mr. 
Leadbeater, which is by many degrees the finest I have 
ever seen, is also without any. 
From these detailed observations it will probably be granted 
that age is not necessary, but that this disease, with its con- 
sequences, may arise at any period during life ; and that the 
