34 CAROTINOIDS AND RELATED PIGMENTS 



washing away the fat and chlorophyll with petroleum ether, taking 

 up the pigment in alcohol and recrystallizing. Hartsen regarded his 

 chrysophyll as probably identical with xanthophyll (G. Kraus) and 

 as existing together with chlorophyll in the leaf. According to Will- 

 statter and Mieg (1907) Hartsen's chrysophyll was probably a xan- 

 thophyll in the sense that this name is u^'d at the present time, but 

 most writers have regarded it as identical with carotin. Bougarel 

 (1877), a little later, isolated red crystals from the alcoholic extract 

 of peach and sycamore-tree leaves. He described the insolubility of 

 the red, green reflecting crystals in alcohol and ether, and their solu- 

 bility in chloroform, benzene and carbon disulfide, as well as the rose 

 color of the solution in the last named solvent. Notwithstanding his 

 familiarity with Hartsen's chrysophyll, which he mentions, Bougarel 

 regarded his pigment crystals as a new substance and unfortunately 

 proposed the name erythrophyll for it, which had already been given 

 by Berzelius (1837b) many years before for the red, alcohol soluble 

 pigment which he isolated from red cherries (Prunus cerasus), black 

 Johannis berries (Ribus nigmm) and the red autumn leaves of vari- 

 ous plants, and which was also used by Sorby (1871, 1873) for a group 

 of water-soluble pigments. The erythrophyll of Bougarel is unques- 

 tionably to be regarded as carotin. 



Dippel (1878) made a careful study of the absorption spectra of 

 G. Kraus' xanthophyll and cyanophyll and the products of the action 

 of KOH and acid on the pigments prepared according to the Kraus 

 method. He found that yellow pigments could be prepared in each 

 case but that the absorption spectrum of the yellow pigment from 

 the acid treatment of cyanophyll was entirely different from the 

 spectra of the yellow pigment from the alkali treatment of both 

 xanthophyll and cyanophyll. Dippel proposed the name xanthin 

 (compare C. Kraus (1875)) for the yellow pigment obtained from 

 Kraus' xanthophyll and cyanophyll on treatment with alkali and 

 extracting with alcohol, and regarded it as the true yellow constituent 

 of chlorophyll. The absorption bands of DippePs xanthin obtained 

 by alkali treatment of Kraus' benzene-cyanophyll layer lay at 490- 

 456|4i and 455-435(.iu, while the bands of Kraus' xanthophyll, as 

 measured by Dippel, lay at 483-460j.iu and 446-433^1. These meas- 

 urements correspond almost exactly with those of carotin and xan- 

 thophyll, respectively, as known at the present time. Dippel's xanthin 

 is to be regarded, therefore, as composed of carotin for the most part. 

 Borodin (1883) made one of the most striking contributions to our 



