PIGMENTS 119 



Morin, found in yellow wood (Morus tinctoria), 



o H0 



HO/ VV^ ~\>H 



Gentisin, found in yellow gentian (Gentiana lutea), 



XX 



JOH 



y \n/ \/ 

 H( 



II 

 O 



As a rule, the most brilliant of these yellow pigments are found 

 in the largest quantities in the bark and wood of various species of 

 tropical plants; although they are also present, in smaller amounts, 

 in the blossoms of species growing in temperate zones. 



The anthoxanthins are easily converted into anthocyanins, 

 and vice, versa, by the action of oxidizing and reducing enzymes 

 which are commonly present in the tissues of the plants which 

 develop the pigments. 



THE PRODUCTION OF ORNAMENTAL PIGMENTS IN FLOWERS, ETC. 



The breeding of flowering plants having blossoms of almost 

 any desired color has become a commercial enterprise of large 

 importance. The results which have been obtained, in many 

 cases, have been made the object of scientific study of the genetics 

 of color inheritance. These studies have developed certain inter- 

 esting facts with reference to the chemistry of the development of 

 these ornamental pigments, which may be briefly mentioned here. 



In many of the plants which have been studied, the color of 

 the flowers depends upon several different factors, as follows: 



C, a chromogen (or color-producing substance) which is gen- 

 erally a flavone or xanthone glucoside, and which may be either 

 yellow or colorless. 



