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



an unsaturated hydrocarbon. He gave it the formula C 26 H 38 and the 

 iodine derivative the formula C 26 H 38 I 2 . 



Eiiler and Nordenson 1 report the most recent investigations in 

 regard to the carrot pigment. They found their crystalline prepara- 

 tion to be mixed with crystals of xanthophyll ; they also showed that 

 the belief often advanced that carotin is chemically related to choles- 

 terol, is unfounded. 



The Carotin of Green Plants. Arnaud 2 was one of the first in- 

 vestigators to show that the carrot carotin is identical in properties 

 with a yellow constituent of chlorophyll, although the existence of 

 this yellow constituent of chlorophyll had long been the subject of 

 investigation. 



Berzelius 3 first sought to isolate a yellow pigment from autumn 

 leaves by extracting with alcohol. He called it "Blattgelb" or xantho- 

 phyll, and expressed the belief that the pigment pre-existed along with 

 the green coloring matter of the leaf. 



The subject subsequently received the attention of many investi- 

 gators. Fremy, 4 Michels, Millardet, Miiller, Tinisnsseff, Gerland, Ran- 

 nenhoff, Askennasy, Stokes, Sorby, 5 Tschirch, 6 Kraus, 7 Filhol, 8 

 Hansen, 9 Conrad, 10 Wiesner, 11 and many others took up the investiga- 

 tion. 



Fremy designated the yellow pigment Phylloxanthin. Filhol 

 noticed that by treating crude alcoholic chlorophyll solutions with ani- 

 mal charcoal it was possible to remove the green constituent of the 

 mixture leaving a yellow colored solution, the color of which he be- 

 lieved was due to a pre-existing pigment or pigments associated with 

 the green one. Kraus confirmed the observations of Filhol, and was 

 the first to notice that when an alcoholic solution of chlorophyll is 

 shaken with benzoline (petroleum ether) the alcohol retains the yellow 

 coloring matter, the benzoline taking up the green constituent. Kraus' 

 investigation was also the first to show that the ordinary chlorophyll 

 spectrum was due partly to the green and partly to the yellow con- 

 stituent, which he called xanthophyll. Kraus' xanthophyll gave a 



1. Zeit. f. Physiol. Chem. 56, p. 223 (1908). 



2. Compt Rend. 100, p. 751 (1885); 104 p. 1293 (1887). 



3. Ann. d. Chem. 21, p. 257 (1837). 



4. Ann. Sc. Nat. 13, p. 45 (1860); Compt. Rend. 41, p. 189 (1865). 

 6. Proc. Roy. Soc. 21, p. 456 (1875). 



6. Botan. Zeitung. 42, p. 817 (1884). 



7. Flora, p. 155 (1875). 



8. Compt. Rend. 39, pp. 9-184; 50, pp. 545 and 1182. 



9. Sitz. ber. d. phys. Med. Ges. Wiirzberg (1883); and Arbeiten d. Botan. 

 Gessel. Wurzberg, 3, p. 127 (1884) and "Die Farbstoff des Chlorphylls" (1889). 



10. Flora, Vol. 25 (1872). 



11. Flora, Vol. (1874); Sitz. der. Wein. Akad. 89, 1. abts. p. 325. 



