476 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



sulphuric acid. Courchet notes that the petals of Gentaurea collina, and 

 the staminal filaments of Dianclla also, have xantheic pigments belong- 

 ing to the same subdivision. The cell-walls of the epidermis of the 

 callus masses in the throat of the flower of Phaius Humblotii are 

 stained by a yellow pigment which becomes orange on treatment with 

 strong sulphuric acid. 



Xantheic pigments of the other subdivision, those which are unaffected 

 in colour by concentrated sulphuric acid, or which become a clearer 

 yellow colour with that reagent, are moderately frequent. 



Courchet notes that the portion of the petal of Anagallis arvensis 

 which lies just above the claw owes its colour to an orange-red cell-sap, 

 which becomes a clear yellow on treatment with mineral acids and alkalis. 

 The claw contains anthocyan, and where the xantheic pigment borders on 

 the cyanic, both pigments are present in the same epidermal cells. Here 

 alkalis produce a green colour due to the blue anthocyan plus the yellow 

 xantheic pigment. The same observer notes that the ovary of Salpiglossis 

 contains an orange-red cell-sap which is unchanged in colour by solution 

 of potash, but becomes a clear yellow colour by strong sulphuric acid. 



The common yellow Crocus of the garden owes its colour to a yellow 

 epidermal cell-sap which, in situ, gives no evident colour reaction with 

 mineral acids and alkalis. The pigment may be extracted with alcohol, 

 and on evaporation of the solvent the amorphous residue, of a clear orange- 

 red colour, dissolves in strong sulphuric acid to a fine green solution, and 

 in potash solution with a greenish-yellow colour. The pigment which 

 gives the stigmas their fine red colour is identical with that of the perianth 

 segments, but it is present in much greater quantity. 



The yellow Primrose owes its colour to yellow epidermal cell-sap in 

 the upper part of the petals, to yellow chromoplastids in the portions 

 close to the corolla tube. No variety of this Primrose has lost this central 

 yellow pigment. The xantheic pigment is slightly deepened in colour by 

 mineral acids and alkalis. In a slightly flushed form of the flower 

 epidermal cells containing yellow sap may be seen lying side by side with 

 others containing rose-coloured anthocyan. 



All the yellow Roses which I have been able to examine owe their 

 colour to xantheic pigment dissolved in epidermal cells. Strong sulphuric 

 acid gives a deeper yellow colour to this, as also to a very light yellow 

 Lupin which I have examined. 



Strasburger * points out that the epidermal cells of the staminal 

 filaments of the flowers of Verbascum nigrum contain, immersed in 

 yellow sap, irregular lumps of a cinnabar-red pigment. 



From the foregoing notes it will be evident that the xantheic series 

 of pigments consists of several distinct substances. The soluble pigment 

 which can be obtained from Narcissus Tazctta, ' Grand Soleil d'Or,' as we 

 as from Eschscholtzia calif ornica, is certainly a glucoside, and that obtaine 

 by Courchet from Linaria vulgaris appears to have properties similar t 

 some of the Flavone group of Phenolic colouring matters which have i 

 recent years been isolated by A. G. Perkin and others from various part 

 of plants, including flowers. t These colouring matters are obtained b 



* Strasburger, Practical Botany (English translation), p. 41. 

 f Chemical Society's Journal, 1890, ct scq. 



