20 



PHYSIOLOGY or NUTRITION 



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

 the spectrum (Fig. lo).' 



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

 tion product of carotin, with the formula C40H66O2.* 



Lyrovin 



Karotin 



Fig. 10. — Absorption spectra of carotin and lycopin. (After Escher.) The Fraunliofer 

 lines^re indicated by the letters above and the wave-lengths (in 10 /ifi) are shown below; the 

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



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

 (C40H66); it is found in the fruit of the tomato {Solanum lycopersicum) . Three 

 dark bands occur in the right half of its absorption spectrum (Fig. 10). 



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

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



Pig. II. — Absorption spectra of carotin (above) anA xanthophyll (below). (.After Will- 

 statter and Stall.) The Fraunhofer lines and the wave-lengths (in ju,i) are shown on the upper 

 line of each diagram. 



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

 37: 909-919. 1904. [Willstatter, Richard, and Escher, Heinr. H.. Ueber den FarbstoEE der Tomate. 

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



' The absorption spectra of carotin and xantophyll, 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. 



