324 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN No. 9. 



crystals have a melting point of 172 C. (corrected) which is slightly 

 higher than the melting point of the carotin crystals ; and the absorption 

 bands of the pigment are slightly shifted toward the violet from the 

 corresponding bands of carotin, as was also shown by Schunck x for 

 the xanthophylls which he differentiated. 



It might be readily assumed that xanthophyll is formed directly 

 from carotin in the plant. In fact Tschirch 2 has claimed that carrot 

 carotin goes over to xanthophyll in the air. Eiiler and Nordenson 3 

 do not credit this statement and state that, "One may well suppose 

 that in the plant, xanthophyll normally is formed from the carotin, 

 but outside of the plant it has not been possible to imitate this trans- 

 formation, the most skillful oxidation always leading to a much 

 higher oxidized product." Willstatter and Meig believed in this con- 

 nection that xanthophyll although carotin dioxide is not the end pro- 

 duct of the oxygen absorption of carotin in the plant. Monteverde 4 

 and Lyubimenko have recently claimed that chlorophyll and xantho- 

 phyll originate from the same colorless substance, carotin being a 

 complimentary product generated during the formation of cholorophyll, 

 but not necessarily from the xanthophyll. 



The Pigments of Animal Origin. 



The Luteins. We will now direct our attention to a review of the 

 literature bearing upon the yellow pigments of so-called animal origin. 

 Thudichum 5 was one of the first to investigate the yellow animal pig- 

 ments and he classified a great many of them together with the yellow 

 pigments of plants under the name lutein, the name being taken from 

 the pigment of the corpus luteum. He states, "Various parts of 

 animals and plants contain a yellow crystallizable substance which has 

 hitherto not been defined, and which I call lutein. It occurs in the 

 corpora lutea of the ovaries of animals, the serum of the blood, the 

 cells of adipose tissue, in butter, in the yolks of eggs of oviparous 

 animals, in seeds such as maize, in husks and pulps of fruits such 

 as annatto, in roots such as carrots, in leaves such as those of coleus, 

 and in the stamens and petals of a great many flowers.'' 



It is unfortunate that none of the above statements are supported 

 by experimental evidence, for it can hardly be accepted that Thudichum 

 was able to obtain crystals of lutein from all the bodies in which he 



1. Loc. cit. 



2. Ber. Botan. Gessel. 22, p. 414 (1904). 



3. Loc. cit. 



4. Bull. Acad. Imper. Sc. St. Petersb. 30, p. 609 (1912). 



5. Proc. Roy. Soc. 17, p. 253 (1869). 



