150 Miss Wheldale, On the nature of anthocyanin. 



The flowers of the original type in Narcissus Tazetta owe 

 their colour to the presence of several pigments ; the lemon 

 yellow of the perianth segments is due to plastids containing 

 xanthin, and the orange yellow of the corona to plastids containing 

 both xanthin and carotin. In addition, all parts of the flower 

 contain a yellow flavone pigment which crystallises from the 

 extract in clusters of yellow needles. To ascertain something 

 of its nature, this yellow crystalline pigment was fused with 

 caustic alkali, the melt dissolved in water, neutralised and 

 precipitated with basic lead acetate. The precipitate on de- 

 composition with sulphuretted hydrogen and extraction with 

 ether, gave a crystalline body having the properties of proto- 

 catechuic acid. The ether extract also gave evidence of the 

 presence of phloroglucin. Hence there is little doubt that the 

 Narcissus pigment may be placed in the flavone series. 



A white variety of the same Narcissus has no plastid pigments 

 but a pale yellow non-crj'stallisable flavone having the usual 

 characteristics. On fusion with caustic alkali, phloroglucin and 

 parahydroxybenzoic (?) acid were detected as decomposition 

 products. Hence the flavone of the variety must differ in 

 constitution slightly from the crystalline flavone of the type. 



A second variety has the crystallisable flavone only in the 

 perianth, while the corona contains carotin, 



A third variety contains a non-crystallisable flavone and 

 xanthin in addition in the corona. 



In a similar way the non-crystallisable chromogen from the 

 white flowers of Primula stellata and P. sinensis was isolated 

 and fused with alkali. The ether extract contained phloroglucin 

 and another body, very probably parahydroxybenzoic acid, since 

 it gave a red precipitate with aqueous iodine and caustic potash, 

 which became yellow on addition of acid. 



The work of Naylor and Chappel^^ on Rosa gallica forms 

 an additional confirmation of the above suggestion as to the 

 nature of the aromatic chromogens. These authors isolated from 

 the petals of the above species of Rosa a yellow crystalline colouring 

 matter, giving an orange-red precipitate with lead acetate and 

 a brownish-black colouration with ferric chloride. 'It was soluble 

 in caustic potash to a yellow or orange brown solution and in 

 sulphuric acid to an orange-yellow liquid. 



Fused with caustic potash it gave phloroglucin and proto- 

 catechuic acid. 



Heise^^ also found protocatechuic acid as a decomposition 

 product from the fusion with alkali of one of the anthocyanic 

 pigments isolated by him from the Bilberry, 



If the existence of a colourless chromogen as a precursor of 

 'anthocyanin' be accepted, it is possible that the recent work 



