JO 



PHYSIOLOGY OF NUTRITION 



The absorption spectrum of carotin has two dark bands in the green-blue half of 

 the spectrum (Fig. 10). 



A second yellow pigment accompanying chlorophyll is xanthophyll, an oxida- 

 tion product of carotin, with the formula doH^C^. 1 



Lijropin 



Fig. io. — Absorption spectra of carotin and lycopin. (After Escher.) The Fraunhofer 

 lines are indicated by the letters above and the wave-lengths (in ю щл) are shown below; the 

 thickness of layer employed is given (in mm.) at the left. 



Lycopin 1 is closely related to carotin and has the same percentage formula 

 (C 4 uH 56 ) ; it is found in the fruit of the tomato (Solanum lycopersicum). Three 

 dark bands occur in the right half of its absorption spectrum (Fig. io). 



Fig. ii. — Absorption spectra of carotin (above) and xanthophyll (below). (After Will- 

 slätler and Stoll.) The Fraunhofer lines and the wave-lengths (in pp) are shown on the upper 

 line of each diagram. 



Red algae contain phycoerythrin, a protein-like substance, which is readily 

 soluble in water but insoluble in alcohol, ether, and carbon bisulphide. The 



1 Montanari, Carlo, Materia colorante rossa del pomodoro. Le Stazioni Sperimentali Agrarie Italiane 

 37: 900-919. 1904. [Willstatter, Richard, and Escher, Heinr. H., Ueber den Farbstoff der Tomate. 

 Zeitsch. physiol. Chem. 64: 47-61. 1910.] 



' The absorption spectra of carotin and xanthophyll, as given by Willstatter and Stoll 

 (1913) [see note b, p. 6] are here reproduced as Fig. 11. It is questionable whether xanthophyll 

 is actually formed by the oxidation of carotin. — Ed. 



