3IO A HISTORY OF BIRDS 



Other colour varieties can also be produced by experiment. 

 The cases of cayenne-fed canaries is perhaps the best-known 

 instance of this. The cayenne has the effect of intensifying 

 the yellow colour until it assumes a rich orange hue ; but this 

 change is only possible when the colouring matter is adminis- 

 tered when the birds are very young. The increased colour is 

 produced, according to Miss Newbigin — who has made a 

 special study of animal pigments — by the intervention of a fat 

 —apparently triolein, a constituent of red pepper. This is of in- 

 terest because, as she has shown, fat pigments {lipochromes) are 

 almost always associated with yellow and red colours. While 

 this abnormal diet, however, in some races of canaries produces 

 the desired orange colour, in others it results in a crimson 

 colour, while in some no effect at all is apparent. Some white 

 breeds of fowls are similarly affected by cayenne pepper, as 

 was shown by the German scientist Sauermann, who adminis- 

 tered this stimulant upon white Italian fowls, eight weeks old. 

 Shortly after, in one case within ten days, orange-striped 

 feathers appeared. Later the whole plumage became streaked 

 with orange, while the breast, it is significant to note, became 

 red. Ten birds, however, which were included in this experi- 

 ment showed no change whatever. 



The natives of the Amazonian region, for example, feed the 

 Common Green Amazon Parrot {Chrysotis festivd) with the fat 

 of large siluroid fishes, and the birds thus treated become 

 beautifully variegated with red and yellow feathers. In the 

 Malay Archipelago the natives of Gilolo similarly change the 

 colour of another Parrot {Lorius garrulus), and thus produce 

 the " Rajah" or King Lory. 



" In Brazil," says Dr. Gadow, " ' contrafeitos ' of the various 

 species of Chrysotis are fashionable. These are produced by 

 the rubbing in of the cutaneous secretion of a Toad {Bufo 

 tinctorius) into the budding feathers of the head, which then 

 turn out yellow instead of green." It is said that after each 

 successive moult these artificially induced yellow feathers re- 

 appear. 



