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THE AMERICAN NATURALIST [Vol. XLIX 



FLOWER PIGMENTS 

 Recent researches by Wheldale and Bassett 1 have shown that 

 there are four flower pigments, i. e., ivory, yellow, red and 

 magenta, in Antirrhinum majus, and that these, in various com- 

 binations and in different states of concentration and dilution, 

 are responsible for all the color varieties. The ivory and yellow 

 pigments have been identified with apiirenin and luteolin respec- 

 tively, i. e., members of the class of soluble yellow plant pigments 

 containing carbon, hydrogen and oxygen: the red and magenta 

 pigments are anthoeyanins. The yellow, red and magenta pig- 

 ments occur only in the epidermis of the corolla, but ivory is 

 present in the inner tissues. The pigments are present in the 

 plant as glucosides. that is combined with sugar. For prepara- 

 tion, the flowers are boiled with water, the pigments precipitated 

 as insoluble lead salts from the filtered solution by adding lead 

 acetate. The lead salts are filtered off and decomposed with di- 

 lute sulphuric acid which forms insoluble lead sulphate and sets 

 free the pigment again in dilute acid solution. These solutions 

 are then boiled for several hours, whereby the sugar is split off 

 from the glucoside and the free pigment, which is less soluble, 

 separates out and is filtered off. The anthoeyanins are separated 

 from the yellow (flavone) pigments by extracting the latter with 

 ether in which the anthoeyanins are insoluble. The red and 



age of oxygen than the flavones" ° Determination of the molec- 

 ular weights of the anthoeyanins also indicates that their 

 molecules are larger than those of the flavone pigments^ Hence 

 if the anthoeyanins are derived from the flavones, it seems likely 

 that the process is one of oxidation accompanied by condensation 

 of two or more flavone molecules or the union of flavone mole- 

 cules with other allied compounds in the plant. It is possible that 

 the factors for red and magenta color will come to be expressed in 

 terms of chemical substances which condense with the flavones to 



M. W. 



i Wheldale, M., ' ' The Flower Pigments of Antirrhinum majus. 1. Method 

 of Preparation," Biochem. Jour., 1913, 7, 87. Wheldale, M., and Bassett, 

 H. LI., "The Flower Pigments of Antirrhinum majus. 2. The Pale Yellow 

 or Ivory Pigment," Biochem. Jour., 1913, 7, 441; "The Chemical Interpre- 

 tation of Some Mendelian Factors for Flower-color," Proc. Boy. So*, 1914, 

 B, 87, 300; "The Flower Pigments of Antirrhinum majus. 3. The Red and 

 Magenta Pigments," Biochem. Jour., 1914, 8, 204. 



