Miss Wheldale, On the nature of anthocyanin. 151 



of Palladin^' may throw light upon the method of production 

 of the pigment from its chromogen. The above author maintains, 

 on the evidence of Bertrand^*, that oxydases can only oxidise 

 aromatic compounds of a certain constitution, and since the 

 products of oxidation may be coloured Palladin terms such 

 oxydases 'pigment-building.' He further maintains that chromo- 

 gens are present in many plants ; for he found that if the 

 extracted sap of such plants be heated sufficiently to destroy 

 the enzymes existing in the plants themselves, then the addition 

 to the extracted sap of a small quantity of the peroxydase of 

 Chodat and Bach^^^'^'^^^ together with a few drops of hydrogen 

 peroxide, produces a purple, red or reddish-brown colouration. 



As to the constitution of the chromogen, Palladin ■^^ suggests 

 that the evidence of Overton" points to the chromogen as being 

 an aromatic substance combined with sugar and of this nature are 

 glucosides. To quote Palladin: — "Die vorstehend beschriebenen 

 Versuche und ebenfalls diejenigen Overton ergaben, dass 

 verschiedene Zuckerarten ein Material darstellen, aus welchem 

 verschiedenartige Atmungschromogene gebildet werden. Auch 

 Glukoside konnen wahrscheinlich als Material fiir die Bildung 

 der Chromogene dienen, wie es auch Overton vermutete. 

 Zugunsten dieser Voraussetzung spricht der Umstand, dass die 

 meisten pflanzlichen Glukoside Verbindungen verschiedener 

 Zuckerarten mit aromatischen StofFen sind : nach den gegenwartig 

 bekannten Tatsachen sind auch Atmungschromogene nichts anderes 

 als aromatische Verbindungen. Die aromatischen Spaltungs- 

 produkte der Glukoside liefern bei der Oxydation verschiedene 

 Pigmente. Es ist wohl moglich, dass die bei der enzymatischen 

 Spaltung der Glukoside in den Pflanzen entstehenden einfacheren 

 aromatischen Verbindungen direkt als Atmungschromogene 

 fungieren." 



The peroxydase of Chodat and Bach employed by Palladin 

 is prepared from the root of the horse-radish. Methods of 

 preparation are given by De Stoecklin^^ and are based upon 

 the extraction of the ground root with water or dilute alcohol 

 and subsequent precipitation w;ith absolute alcohol. The ferment 

 separates out as a white powder, which may be purified by solution 

 and reprecipitation. The activity of the ferment can be tested by 

 its power to produce purpurogallin when added to pyrogallol 

 solution in presence of hydrogen peroxide. 



I have prepared the peroxydase by the method of De Stoecklin 

 and have tested its action upon an extract of flowers of Primula 

 sinensis. Flowers of a white variety slightly tinged with purple 

 were gently heated in water and subsequently pounded and filtered. 

 To the colourless extract a little of the peroxydase solution was 

 added, together with a few drops of hydrogen peroxide. With 



VOL. XV. PT. 11. 11 



