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 



