68 CAROTINOIDS AND RELATED PIGMENTS 



scopic similarity of alcoholic extracts of yellow flowers with the xan- 

 thophyll which he obtained from green leaves by his well-known 

 method of separation of the green and yellow chloroplastid pigments. 

 Sorby (1873) believed that yellow and orange colored flowers were 

 colored by a mixture of the various xanthophylls and xanthines which 

 he described and which have already been reviewed in detail. Dippel 

 (1878) also noticed the similarity between the absorption spectra of 

 flower extracts (he used the golden-yellow flowers of the California 

 poppy (Eschscholtzia calijornica) and the yellow pigments of chloro- 

 plastids. Hansen (1884c) apparently obtained the first crystals of 

 carotinoid from yellow flowers, but their probable impurity is indicated 

 by their ease of solubility in both alcohol and petroleum ether, crys- 

 talline carotin being practically insoluble in the former and crystal- 

 line xanthophylls in the latter solvent. Hansen called the flower 

 plastid pigment lipochrome, because of its similarity in properties to 

 the animal lipochromes which were being studied by Krukenberg 

 (1880-1886) about that time. 



Schimper (1883, 1885) first observed that the orange-yellow pig- 

 ments in the chromoplastids of certain flowers existed naturally in 

 crystalline condition, while in others the pigment was granular or 

 amorphous. These observations were greatly extended by Courchet 

 (1888), who used the name chromoleucites first proposed by van 

 Tieghem in place of chromoplastids. The former has not had such 

 general use as the latter. Courchet's extensive investigation was not 

 confined to the yellow and orange pigments of flowers and fruits, but 

 covered the anthocyanins as well. He described very minutely the 

 morphology and organization of the chromoplastids and the pigments 

 contained therein for many flowers and fruits. He found a very inter- 

 esting relation to exist between the color of a pigment and the form 

 which it assumes in the plant. He showed clearly how to distinguish 

 between red anthocyanin pigments dissolved in the cell sap and red 

 plastid pigments frequently deposited in crystals in the plastids, the 

 latter being characterized by their blue color reaction with con. 

 H 2 S0 4 ; in form and color and reactions with reagents they were shown 

 to be identical with the red crystals in tomato plastids, which were 

 believed at that time to be identical with the carotin of carrots. He 

 demonstrated that yellow-orange and red-orange colors in flowers are 

 always found in the chromoplastids, frequently in the form of crystals 

 whose rhombohedral platelets or prisms were recognized as extraordi- 

 narily closely related to the carotin of carrots and green leaves. He 



