292 



The Bird 



New York Zoological Park, I have had opportunity to 

 record many cases of the effect of food upon colour. An 

 experiment very commonly known is that of feeding 

 canaries on red pepj)er, thus causing their plumage, after 



Fig. '2'.i'2. — Variation due to cliinato. etc.. in races of Xorth Anierii-an Sons; ^^parrows 

 (From a photograph provided by the American .Museum of Natural Hi.story.) 



successive moults, to become of an intense orange colour. 

 This is the more remarkal)le since the actual red pigment, 

 or capsicin. of red ])ep])er is not the direct cause of the 

 canaries' changed hue. h\\\ n fatty substance known as 

 triolein, which is a constituent of tlie pe}i]ier. 



