1915] B. Horowits 169 



(d) So-called anthocyan pigments (red and magenta). These 

 may arise in the oxidation of phenols by organic oxygen 

 carriers : contaln C, H, O.^^ 

 Chlorophyll. Willstätter^*^ has shown thät the amorphous 

 and the crystalline varieties of Chlorophyll are esters of the tri-car- 

 boxylic acid, chlorophyllin, C3iH29N4Mg(COOH)3, the amor- 

 phous being the methyl-phytyl ester, 



COOH 

 C3iH29N4Mg^COOCH3 



^COOC20H39 



and the crystalline, the methyl-ethyl ester, 



COOH 

 C3iH29N4MgfCOOCH3 



COOC2H5 



The fact that Carotin and xanthophyll are always associated 

 with Chlorophyll has led to attempts to trace the origin of the latter 

 to them. Thus far this has met with no success. However, Mon- 

 teverde and Lyubimenko,^^ in studying the transformation of the 

 green leaves of many plants that turn reddish-brown or red in the 

 autumn, have isolated from the red leaves a red pigment (rhoda- 

 xanthin) which they suppose is isomeric with xanthophyll. 



Most authors seem to be agreed that light is a most impor- 

 tant factor in the formation of Chlorophyll. Palladin^^ ^nd D'Ar- 

 bamont^^ consider sugar a necessary intermediary, the latter adding 

 starch also. But, even if this were so, the difficulties for the chem- 

 ist in tracing the synthesis of Chlorophyll, with carbohydrate as the 

 starting point, would but begin, now that we know what Chlorophyll 

 is chemically. 



Carotin, C40H56, and xanthophyll, C40H56O2. It has al- 



lö It is interesting to note here that Tswett {Ber. d. deut. bot. Gesell, 1906, 

 xxiv, p. 326; 1907, XXV, p. 137), from studies in absorption spectrum analysis, 

 concluded that there are at least seven diflferent coloring-matters in leaf -pigment. 



20 See West's comprehensive review of Willstätter's book on Chlorophyll : 

 BiocHEM. Bull., 1914, iii, p. 229. 



2iMonteverde and Lyubimenko: Bull. Acad. Sei. St. Petersburg, 1913, P- 

 1007; Chem. Abstracts, 1914 viii, p. 728. 



22Palladin: Ber. d.d. bot. Gesell., 1902, xx, p. 224. 



23 D'Arbamont : Ann. Sei. Nat. Bot., 1909, ix, p. I97- 



