160 Miss Wheldale, On the nature of anthocyanin. 



If the cultivated red varieties of Helianihemum vulgare are 

 derived from the yellow type, this would constitute a further 

 example. De Vries* quotes additional cases, i.e. red varieties of 

 Achillea Millefolium, Begonia, semperflorens, Crataegus oxyacantha, 

 Rohinia Pseudacacia, and the red-leaved Beech and Hazel. 



In conclusion I should like to take this opportunity of 

 expressing my thanks to Professor Bateson for his valuable advice 

 and help in this research. I am also indebted to Mr H. O. Jones 

 for suggestions in connection with the chemical portion of the 

 subject. 



Summary. 



1. Chroraogens, pale or deep yellow in colour (in the latter 

 case the so-called soluble yellow or xanthe'ic pigments), and of 

 the nature of the flavone and xanthone classes of natural colouring 

 matters, are widely distributed in plants and are commonly found 

 in connection with the pink, purplish-red and purple series of 

 'anthocyanic' pigments. 



2. These chromogens exist in the plant probably in com- 

 bination with various sugars, i.e., as glucosides. Most of them 

 may be regarded as compounds of phloroglucin with protocate- 

 chuic acid, hydroxybenzoic acid or sometimes resorcylic acid. 

 Occasionally pyrocatechol or some other phenol takes the place 

 of phloroglucin. 



3. Overton's work on 'anthocyanin' from the point of view 

 of nutrition, also points to the conclusion that this pigment is 

 a glucoside compound of a tannic acid. 



4. On the evidence of the recent work of Palladin in 

 connection with plant respiration, chromogens of an aromatic 

 nature are widely distributed and are able to produce red and 

 purple pigments when acted upon by the peroxydase of Chodat 

 and Bach in the presence of available oxygen. Hence it is 

 highly probable that the bodies mentioned above may constitute 

 these chromogens. 



5. Evidence from cross-breeding in Antirrhinum goes to 

 prove that for the production of the 'anthocyanin' of the type, 

 two bodies are essential, i.e., an aromatic chromogen of the 

 flavone series and a reddening factor, in all probability an 

 oxidising ferment. 



* Species and Varieties, their Origin by Mutation. 



