250 
COLOUR IN NATURE 
CHAP. 
without moult, but it can be demonstrated that the 
feathers possess their peculiar colouring before they 
leave their sheaths. These statements are true only 
of birds which display complex colour-patterns, and 
which require years to completely attain the typical 
plumage. Schenkling is of opinion that a more 
careful study of such cases will greatly modify 
existing views as to the rigid limits of each moult. 
Food and Colour 
It may perhaps be well to mention here for the 
sake of completeness the colour-changes which may 
be produced in some birds by supplying coloured 
food. An account of these changes will be found 
in Mr. Beddard’s Animal Coloration. In the case of 
the canary it is well established that the addition of 
cayenne pepper to the food will change the colour 
from yellow to deep orange, or flame colour. Mr. 
Beddard also cites the artificially produced change 
from green to yellow in Brazilian parrots as another 
instance of the effect of food on colour, but there 
seems some doubt whether the change in this case 
is not produced by direct local application to the 
young feathers. In the case of the canary the 
change can only be produced in very young birds, 
which is so far evidence against the view that 
mature feathers can change colour. In the canary 
the change is produced by means of the intervention 
of a fat,—a point of some interest because the 
association of introduced pigments with fats is so 
common—is perhaps universal. Similarly the Rajah 
Lori is said to attain its brilliancy from a diet of 
