50 



Miss M. Wheldale. Colours and Pigments of [Oct. 31, 



a reddish colour, but with other bases a clear yellow, and with basic lead 

 acetate an orange-red precipitate. In the stems and berries of Phytolacca 

 decandra, the magenta and crimson flowers of Mirabilis Jalapa- and Portulaca 

 grandiflora, two pigments apparently exist. One, insoluble in alcohol but 

 soluble in water to a magenta solution, gives reactions on the whole similar 

 to those given by the red pigment of Amaranthus. The other pigment is 

 soluble in alcohol to a crimson solution, which gives a yellow colour with 

 acids and alkalis and a reddish precipitate with basic lead acetate. 



Overton (9) is also of the opinion that anthocyanin contains several classes 

 of pigments, of which he gives — (1) the Amarantaceos and Beta vulgaris, 

 (2) Papaver Rlmas and other species of Papaveraceee, (3) Tradescantia 

 discolor* and other Commelinacea}. 



The alcoholic solution of the red pigment in some genera is colourless, the 

 colour returning on evaporation or on addition of acid. In other cases, again, 

 the alcoholic solution is as deeply coloured as the flowers. It is possible that 

 these phenomena may indicate a difference in the nature of the pigments. 



Lastly, it might be well to mention that anthocyanin is said to occur in 

 solid and crystalline states in the cell. Many instances are cited by 

 Molisch (8) in his work on crystalline anthocyanin. 



Xanthein. 



Xanthein, like anthocyanin, includes at least several pigments varying in 

 their reactions towards acids and alkalis. They may be classified as follows : — 



1. Those giving a deeper yellow, orange, or orange-red colour with acids 

 and alkalis and similarly coloured precipitates with basic lead acetate. 

 Such pigments are found in yellow varieties of Althaea rosea, Antirrhinum 

 majus, Calceolaria, Coreopsis, Dahlia variabilis, Dianthus Caryophyllus, 

 Helichrysum bracteatum, Phlox Drummonclii and Tagetes signata. 



2. Those in which the yellow colour becomes paler with acids and alkalis 

 and basic lead acetate gives, as a rule, no precipitate or a precipitate of the 

 same colour as the pigment. Such is the case in Mirabilis Jalapa, 

 Montbretia sp., Nemesia strumosa, Papaver nudicaule, and Portulaca grandiflora. 



3. Those in which the yellow colour remains unaltered in the presence of 

 acids and alkalis, and basic lead acetate gives a yellow precipitate, as in 

 MesembryaMthemum pomeridianum, Verbascum. 



If xantheie pigments are derivatives of anthocyanin, the dissimilarity 

 of the former among themselves strengthens the view that the reds, from 

 which they are derived, are also dissimilar. 



* I have not been able to detect so far any divergence in this case. 



