AVIAN CAROTENOIDS 



green component is identical with lacertofulvin (see p. 226). Recently 

 Wald '^ 3 has detected a new carotenoid, galloxanthifi, in chicken retinas. 

 This pigment, which has not yet been obtained crystalline, has absorp- 

 tion maxima, at wavelengths, which at the time of this investigation, 

 were lower than those normally encountered in the carotenoid series 

 (Table 45). Karrer's work on carotenoid epoxides has since been 

 published (see p. 15), and it is possible that galloxanthin belongs to 

 this group of pigments. It is strongly adsorbed on calcium carbonate 

 and gives a band at 785-795 my., with SbClg ; the position of galloxan- 

 thin in relation to the three types of oil droplets has not yet been 

 defined. 



Feathers 



The contribution which carotenoids make to the pigmentation of 

 the plumage of birds is considerable, and feather carotenoids can be 

 considered analogous to the carotenoids stored in the external structures 

 of sea creatures. In both cases the carotenoids are xanthophyllic, 

 produced by the animals from the alimentary carotenoids, and as often 

 as not are characteristic of the species. 



Palmer 2 1 gives a full description of the earUer work on plumage 

 lipochromes which was originated by Krukenberg. This has also been 

 briefly summarized by Karrer and Jucker. ^ * Lonnberg ^ ^ has reported 

 the presence of carotenoids in the feathers of a large number of species 

 of birds but more searching chemical investigations have been under- 

 taken by Brockmann and Volker, i« Test, ^^ Kritzler ^ '. ^ s and 

 Volker. ^ 9- * 2 Brockmann and Volker ^ * discovered that canary feathers 

 contained a pigment which was very similar to both violaxanthin and 

 taraxanthin but distinct from either and they named it canary xantho- 

 phyll. It was characterized by its absorption spectrum, by its failure 

 to give a blue coloration with ethereal HCl, and by its greater adsorb- 

 ability than lutein (xanthophyll). They found that the canary was the 

 only bird whose feathers contained only canaryxanthophyll. The 

 other widely distributed feather carotenoid is lutein (xanthophyll) 

 and Brockmann and Volker found that they could divide birds into 

 three groups according to whether their feathers contained (a) mainly 

 lutein (xanthophyll) and a little canaryxanthophyll, (h) a little lutein 

 (xanthophyll), or {c) considerable canaryxanthophyll. Two other less 

 common pigments were also noted ; picofulvin, in the green feathers of 

 Picus canus and P. viridis, and a red pigment in Pyrotnelana franciscana. 



The work of Test** on the feathers of the yellow woodpecker 

 (Colaptes auratus) indicated the presence of three pigments, (i) a 

 taraxanthin-like pigment, (ii) an unidentified red neutral carotenoid 



261 



