271 
change in the plumage of some hen-pheasants. 
first three primaries of each wing also white, was opened in 
the presence of two persons, and found to be under the 
influence of the same sort of disease apparent in the organs 
of a hen-pheasant examined at the same time by way of 
comparison. This partridge was one of a covey bred during 
the summer of 1826, several of the young birds of which 
exhibited some white feathers. This circumstance was often 
noticed by the keeper, but only one bird was procured. The 
clay-coloured legs, as well as the plumage in this specimen, 
were additional evidence that this partridge also was a bird 
of the year. 
A few of the feathers on the breast bore the chesnut colour 
peculiar to the male of this species. 
It may be objected to this example, that the colour of the 
altered feather was not entirely that of the male; but I have 
quoted this instance in order to show that it was a young 
bird ; that the female organs were destroyed by disease ; and 
that a change in the colour of the plumage had taken place. 
The assumption of plumage decidedly resembling that of 
the male, must not however be confounded with accidental 
varieties. All variations of feathers are not caused by an 
alteration of the sexual organs. I have examined several 
birds of various species in which those parts were perfectly 
healthy; but such birds are generally smaller than the 
natural size of the species to which they belong ; and the 
variety of plumage in them probably originates in an imper¬ 
fect secretion arising from weakness. 
That this disease arises at later periods during the life of 
the bird, but still long previous to a natural cessation of the 
powers of reproduction as a female, seems almost certain 
