152 Miss Wheldale, On the nature of anthocyanin. 



care the formation of a purple pigment can be detected as the 

 oxydase is added, though it rapidly vanishes leaving a brown 

 colouration only. The same restoration of the pigment is brought 

 about sometimes by the addition to the extract of hydrogen 

 peroxide only, in which case evidently some of the Primula 

 oxydase is still active. It seems probable that the rapid dis- 

 appearance of the restored pigment is due to some unfavourable 

 condition of the experiment. 



An attempt to isolate an oxydase from the young flowers 

 and buds of coloured varieties of Primula sinensis has resulted 

 only in the production of a solution which gave a brownish-red 

 colour with pyrogallol in presence of hydrogen peroxide but which 

 was without effect upon the colourless extract of Primula itself 



Although no positive result has been obtained with Primula 

 oxydase on its own chromogen, further attempts will be made 

 to isolate a peroxydase from other genera, such as Antirrhinum, 

 Lathyrus, etc., and it is possible that these may be more successful. 



The theories of Palladin and Overton however, taken into 

 consideration with results derived from work in genetics and from 

 the researches of Perkin, seem to provide evidence sufficiently 

 strong to justify the assumption, that anthocyanin is a product 

 of ferment oxidation of the glucosides of members of the flavone 

 series of colouring matters, or of substances very closely allied 

 to these. 



If we regard anthocyanin as the product of oxidation of a 

 colourless aromatic chromogen, then the following table of genera 

 having man}' varieties, shows several anomalies : — 



In Antirrhinum, Dianthus, Matthiola and Verbena, the 

 chromogen gives a brown colouration with iron salts, though 

 the reactions with basic lead acetate, with alkalis and with 

 acids would indicate that it is of a similar nature to those already 

 described. In pink — rose doree — Antirrhinum, red Matthiola, 

 scarlet Dianthus and scarlet Verbena, the addition of the reddening 

 factor produces no change in the iron-reaction but only the 

 ultimate addition of a blueing factor, which then produces a green 

 iron-reaction — Antirrhinum, Verbena — or a blue iron-reaction — 

 Matthiola. In pink Dianthus, the reddening factor gives a green, 

 in other varieties the blueing factor, a blue iron-reaction. 



Most frequently, as in Phlox, Lathyrus, Dianthus and Matthiola 

 (exceptions Antirrhinum and Verbena^ as well as in Helianthemum 

 and Abutilon, the introduction of a blueing factor appears to be 

 connected with the production of aa iron-blueing reaction. 



As regards basic lead acetate, the chromogen in Dianthus 

 and Matthiola does not give the usual reaction, so that the 

 reds and purples become bluer on addition of this reagent but 

 no green colour is produced. 



