CAROTINOIDS IN THE PHANEROGAMS 49 



the terminology of Ber/elius for yellow autumn pigments and called 

 the etiolated pigment xanthophyll/' Fremy (I860) naturally regarded 

 the yellow pigment of young sprouts and etiolated leaves as identical 

 with his phylloxanthine and the bluish-green color which develops on 

 treatment with acid (he also found the fumes of HC1 and HNO, very 

 effective) as identical with his phyllocyanine. Sorby (18711) I recog- 

 nized the relation of the yellow pigment of etiolated leaves to other- 

 yellow plant pigments and regarded the color as due to a preponder- 

 ance of his so-called "xanthophyll" group, characterized by their 

 solubility in carbon disnlfide and two more or less distinct spectro- 

 scopic absorption bands in the blue part of the spectrum. (Iregor 

 Kraus (1872b'l compared the spectroscopic properties of the alcoholic 

 extract of etiolated leaves with his xanthophyll pigment which re- 

 mained in the alcohol on shaking leaf extracts with benzene. The 

 results led him to believe that the pigments were probably identical, 

 and he proposed a genetic relation of the etiolated pigment to the 

 green pigment of plants. 



Pringsheim (1874), however, also using a spectroscopic examination 

 of the alcoholic extracts of etiolated leaves as the basis of his con- 

 clusions, found characteristic absorption bands in the red end of the 

 spectrum in addition to bands in the blue which characterized Kraus' 

 xanthophyll. Inasmuch as the same result was obtained for each of 

 10 different etiolated plants which he examined, Pringsheim concluded 

 that a special pigment was present which caused the bands in the red 

 as well as the bands in the blue. He called this pigment ctiolin. 

 Pringsheim's results have been frequently substantiated, and while 

 some subsequent investigators (Wiesner (1877b), Elfving (1882), 

 Tschirch (1884) ) have agreed with his conclusion regarding etiolin as 

 a distinct pigment, a majority (Timiriazcff (1875), Hansen ( 18841) ), 

 Immendorff (1889), Monteverde (1894), Kohl ( 19021'), Greilach 

 (1904) who have studied this phase of the etiolin question have pre- 

 sented convincing evidence that the spectroscopic absorption bands in 

 the red which Pringsheim observed in his etiolated leaf extracts are 



" According to <'/apck I I'.iochemie der IMhin/rii. L'nd Kd. , vol. I, |>. r>7!t. .Trim. r.H.'ii, 

 Julius Sachs MX.V.I ;i. Ill and Jos. Hoehlll (1S.V.M called (he et iolated pigment leuko- 

 pliyll and chlorogon, respectively. Tin- statement is incorrect. The h'ukophyll of 

 Sachs was a colorless chromogcn in the seeds ;iiid also in Hie etiolated plants which 

 gave rise to the green clilornphyll in Ihe sunlight or on treatment with acids i coin- 

 pare Phipson [isr>s|t, while the chlorophor (not chlorogon as C/apek lias it i of Moehin 

 was the same colorless chromouen. r.oehni dilTered from Sachs in regarding the green 

 acid derivative of the colorless chroinogen as an artificial pi.mnent and the green sun 

 light derivative as the true chloi-ophyll. Koth investigators recognised the existence of 

 the yellow etiolated leaf pigment us, well as, the colorless chroinogen. 



