466 
Mr. J. Lewis Bonhote on Moult 
results of the moult are gained without the bird having to 
undergo such a severe strain on its system. 
Mr. Chadbourne goes on to state that all individuals of a 
given species do not acquire their breeding-plumage in the 
same way, some acquiring it by moult, others by colour- 
change, and others again by both processes. This seems to 
show T an intimate connection between moult and change of 
colour. The Bobolink is not the only bird in which the 
method of the assumption of the breeding-plumage varies in 
different individuals. From the head of Larus ridibundus I 
have taken at the same time new brown feathers and old 
feathers in process of change, while in other individuals 
there has been a pure colour-change. The Ruff is an instance 
of the change going on in two different ways simultaneously. 
The Ptarmigan, again, is another instance, and from the 
examples of this species which I have examined I think it 
doubtful whether it assumes any one of its plumages in a uni¬ 
form manner. The fact that a bird will assume its breeding- 
plumage in some feathers by a change of colour, and in 
others by a change of feather, leads to the supposition that 
pigment can find its way up an old and fully-grown feather. 
It does not seem to me unlikely that, at a certain season, 
pigment—which is chiefly a waste product, more abundant, 
on account of the extra energy expended, at the approach of 
spring—should be deposited in the follicles of the feathers. 
If the follicle is at that time engaged in producing a new 
feather, the pigment is placed in it; if not, it is drawn up 
into the feather which is already full-grown. The fact of 
one individual moulting and another not casting a feather 
offers no real difficulties, as moult is influenced by many 
different causes, some of which, e. g. heat, food, vigour, 
&c., are directly dependent on the individual and its 
surroundings. 
Let us briefly consider the evidence for and against the 
conveyance of pigment up a feather. Let us take the 
evidence of our own eyes. 
First, for instance, let us select the case of the Golden 
Plover (Charadriuspluvialis ). If a specimen be examined 
