64 University of California Publications in Zoology [VOL. 11 



These instances and the results of the experiments all point 

 to the same conclusion, that with reduced nutrition there is a 

 reduced pigment production along with a reduction of tissue or 

 tissue formation with the result in the case of the tadpole that 

 the color of the animal appears neither darker nor lighter. 



D. EFFECT OF VAEIOUS KINDS OF FOOD UPON PIGMENTATION 



Of especial interest in a discussion of the effect of food upon 

 the color of animals are the following classical examples cited by 

 Darwin (1868, vol. 2, p. 337) in "The Variation of Animals and 

 Plants under Domestication." He says: "It is well known that 

 hemp-seed causes bullfinches and certain other birds to become 

 black. Mr. Wallace has communicated to me some much more 

 remarkable facts of the same nature. The natives of the Amaz- 

 onian region feed the common green parrot (Chrysotis f estiva, 

 Linn.) with the fat of large Siluroid fishes, and the birds thus 

 treated become beautifully variegated with red and yellow 

 feathers. In the Malayan archipelago, the natives of Gilolo alter 

 in an analogous manner the colours of another parrot, namely the 

 Lorius garrulus Linn., and thus produce the Lori rajah or King- 

 Lory. These parrots in the Malay Islands and South America, 

 when fed by the natives on natural vegetable food, such as rice 

 and plantains, retain their proper colours. Mr. Wallace has, also, 

 recorded (A. R. Wallace, Travels on the Amazon and Rio Negro, 

 p. 294) a still more singular fact. 'The Indians (of S. America) 

 have a curious art by which they change the colours of the 

 feathers of many birds. They pluck out those from the part they 

 wish to paint, and inoculate the fresh wound with the milky 

 secretion from the skin of a small toad. The feathers grow of a 

 brilliant yellow colour, and on being plucked out, it is said, grow 

 again of the same colour without any fresh operation. ' ' 



Romanes (1895, vol. 2, p. 218) cites the above instances of 

 changes in the plumage of birds and the fact also noted by 

 Darwin that canaries become red when fed on cayenne pepper, 

 and adds: "Dr. Sauermann has recently investigated the subject 

 experimentally; and finds that not only the finches, but likewise 

 other birds, such as fowls, and pigeons, are subject to similar 



