and Colour-change in Birds. 
469 
Let us now turn for a moment to see what evidence can 
be found on the other side of the question. 
The chief argument is that it is anatomically impossible ; 
that a feather once formed has no longer any connection 
with the blood-system, and is therefore technically a dead and 
cast-off' structure, and that consequently pigment, which can 
only be brought by the blood, cannot be conveyed to the 
feather. I have already pointed out that experiments made 
by others on the subject clearly prove that it is quite possible 
for pigment deposited at the base of a feather to work its 
way up by purely physical means. If an artificial pigment 
can do this, we need have little doubt that it is possible for 
a natural pigment to do the same. 
The two chief papers that have been written against colour- 
change of recent years are those of Messrs. Allen and Stone*. 
I have read the former, which is a review of papers in favour 
of colour-change, very carefully, and although here and 
there the author points out slight discrepancies in the state¬ 
ments made by other writers, he adduces no proofs in favour 
of non-colour-change. But as it will perhaps be said that 
the burden of proof rests with advocates of the change, I 
will go further, and say that he does not disprove any of 
the statements made in the papers criticised. To deny 
statements flatly, or to cast them aside as “ too obviously 
absurd for serious consideration/’ by no means disproves 
them, but to my mind shows a certain amount of weakness, 
for if there were any good arguments against the theory of 
colour-change, Ur. Allen would surely have brought them 
forward. 
I do not propose to deal at any length with these papers, 
but would like to notice one or two examples of Ur. Allen's 
contradictions. Criticising some notes made by a keeper at 
the Zoological Gardens, who stated that the Ruff assumed the 
summer-plumage on the body-feathers by change of colour, 
Ur. Allen states : “ The Ruff is thoroughly well known to 
moult its body-plumage in spring." Now I have kept Ruffs 
in captivity and shot them wild, and, although 1 know that 
* Log. supra cit. 
2 K 
SER. VII.-VOL. VI. 
