Miss Wheldale, On the nature of anthocyanin. 



149 



Kampherol, G^JiioOg, occurs as a rhamnose glucoside Wohinin' 

 in the flowers of Robinia pseudacacia, and also as another glucoside 

 in the flowers of Delphinium consolida and Prunus spinosa. It 

 may be regarded as a connecting link between apigenin and 

 quercetin : — 



OH 



OH 



OH 



OH 



OH 



OH 



OH CO 



OH 



OH CO 



Quercetin 



Kampherol 



OH 



OH 



OH CO 



Apigenin 



On fusion with caustic alkali it gives parahydroxybenzoic acid 

 and phloroglucin. 



The above account conveys some idea of the wide distribution 

 of the flavone series of colouring matters. Some fifty to sixty 

 genera have been examined by Perkin and his colleagues and 

 these genera are members of many different natural orders. 

 Several of the flavones are common to genera by no means 

 closely allied and again others, as far as his investigations have 

 gone, are apparently specific. The constitution of these bodies, 

 as given above, shows that there is great scope for slight variations 

 and many isomeric forms may exist and may be specific for different 

 plants. At the same time the general nature and tendencies of 

 these bodies are similar, and it is not difficult to conceive of their 

 acting as chromogens in the formation of the various kinds of red 

 pigments found in plants. 



I have repeated the method of extraction of Perkin and 

 HuMMEL^^ for quercetin from onion skins and I find this body 

 very similar in its properties and reactions to the aromatic 

 chromogens present in flowers. Sometimes these bodies crystallise 

 out from the flower extract as in Narcissus Tazetta*, Eschscholtzia, 

 and Viola'f in which case the substance is more easily prepared 

 in its pure state. The yellow crystalline pigment of Viola is 

 without doubt the 'viola quercitrin' of Perkin. 



Bidgood«. 



t Wheldale 20. 



