CAROTINOIDS IN THE PHANEROGAMS 39 



exactly with (hose of xanthophyll, not carotin, as the following table 

 shows: 



Carotin in alcohol Xanlhojih t/ll ni alcohol 



(Willstatter :md Stoll (1913n) (WilUiiiicr and Micj? (1907) 



1492-476 nn 1488-471 mi 



11459-445 " 11454-440 " 



1114307419 " . Ill 425-420 " 



Carrot carotin in alcohol Xanthocarotin in alcolml 



(Tschirch) (Tschirch) 



I 487H170 mi 1485-468 nn 



11457-439 " 11455-438 " 



III 429-417 " III 430-418 " 



Much discussion has also resulted from the statement made by 

 T-chireh in the paper under consideration that he was able to observe 

 the transformation of xanthocarotin into xanthophyll. As a matter 

 of fact Tschirch observed merely that certain impure xanthocarotin 

 solutions lost their absorption bands without losing their color appre- 

 ciably. In view of the fact that the so-called xanthophyll of Tschirch 

 showed no absorption bands but merely end absorption, he conclude* 1 

 that xanthocarotin readily changes over into xanthophyll, a most 

 sweeping conclusion from such indefinite evidence. The author has 

 observed many times that impure solutions of carotinoids lose their 

 spectroscopic absorption bands in the earliest stages of decomposition 

 with little or no loss in color of the solutions. 



A somewhat different system of yellow chromolipoids was proposed 

 by Schunck (1899, 1901, 1903) in his series of papers. He depended 

 largely upon the spectroscopic absorption properties of the pigments 

 for their differentiation, as did Tschirch, and in his later studies upon 

 the action of certain chemical agents upon the absorption bands. It 

 may be stated of Schunck's work, faulty as it was in certain respects, 

 particularly in his adoption of Sorby's method for separating the 

 various yellow coloring matters by carbon disulfide, that he has given 

 us some of the most beautiful spectro-photographs of the carotinoids 

 that exist in the literature. Schunck accepted from the outset that 

 more than one yellow chromolipoid was present in the chloroplastids. 

 Inasmuch, however, as he modified his views somewhat regarding the 

 number and nomenclature of these pigments during the course of his 

 studies his final views only will be discussed. 



Schunck proposed to call all the yellow pigments accompanying 

 chlorophyll xanthophylls, the chief member of the group being chryso- 

 phyll, thus adopting Hartsen's terminology for carotin in spite of the 

 fact that Schunck not only referred to Arnaud's work but confirmed 



