The Production of Anthocyanins and Anthocyanidins. 451 



Reduction under ligroin produced the same results as without protection 

 from air. 



Primula obconica (white). — Petals gave clear yellow on treatment with 

 ammonia, no pink with acids. Extract made as above, almost colourless. 

 Eeduction with zinc in cold 2N HC1 gave good red pigment. The reduction 

 went equally well under ligroin, and in both cases the pigment produced was 

 quantitatively anthocyanin, and could be hydrolysed quantitatively into 

 anthocyanidin. 



Primula sinensis (Giant white). — Petals gave clear yellow with ammonia, 

 no pink with acids. All attempts to obtain a red pigment failed. 



Tulip (yellow). — Extract prepared as above in 2N HC1. With much 

 zinc a faint passing pink colour appears, then solution becomes decolorised, 

 hydrogen peroxide added to the decanted solution causes appearance of red 

 colour. Exposure to air has same effect. The red produced is an anthocyanin 

 readily hydrolysable to an anthocyanidin. 



When acid extract was treated with small quantities of zinc the pink colour 

 soon appeared and deepened. If not taken too far hydrogen peroxide caused 

 no change. 



Electrolysis of cold extract in 2N sulphuric acid, lead electrodes, readily 

 gave the red pigment which, as in the preceding cases, proved to be entirely 

 anthocyanin. 



Tulip (white). — Petals with ammonia gave clear yellow. Exactly similar 

 results were obtained as for the above yellow tulip. Both in the case of 

 yellow and white tulips the reduction went on equally well under 

 ligroin. 



When the extract from the white tulip was boiled to hydrolyse the 

 glucoside contained, then cooled and reduced in the cold, a red .pigment 

 was readily obtained, but it was entirely an anthocyanidin. 



Daffodil (yellow). — Extract as before, zinc in 2N HC1 gave red pigment 

 easily. Electrolysis in 2N sulphuric acid gave same result. In both cases 

 cold reduction gave only an anthocyanin. Eeduction went on to red pigment 

 equally well under ligroin. 



Narcissus (small white). — Petals with ammonia gave clear yellow. Reduc- 

 tion with zinc in 2N HC1 gave only anthocyanin. 



Mimosa. — All attempts to get red pigment failed. 



Hyacinth (white). — Petals gave yellow with ammonia, but all attempts to 

 obtain red pigment failed. 



Crocus (yellow). — Extract as above gave, by zinc in 2N HC1, or by electro- 

 lysis in 2N sulphuric acid, red pigment quite readily, in both cases cold 

 reduction yielded only anthocyanin. 



