THE ANTHOCYAN PIGMENTS 599 



as the result of a reduction of the pigment. These workers used, 

 for their experiments on blue pigments, the cornflower, violet, 

 and iris, and on red ones, the dahlia, rose, and peony. In each 

 case they attempted to purify the pigment by use of the lead salt, 

 as described by Berzelius. In no case, however, did they obtain 

 a pure product. 



Fremy and Cloez discussed the general ideas then current 

 regarding the plant pigments, and pointed out the uselessness of 

 assuming, as so many workers about that time did, that a re- 

 lationship existed between chlorophyll and the blue and yellow 

 pigments, for, as at that time pure chlorophyll had not been 

 obtained, and the flower pigments were almost uninvestigated, 

 no reliable conclusions could be drawn. They concluded that 

 all anthocyans were one and the same substance — they called it 

 cyanin— and the colour variations were due to the properties 

 of the particular sap. They distinguished three flower pigments, 

 (i) Cyanin (red or blue), (2) Xanthins (yellow, insoluble in water), 

 (3) Xantheins (yellow, soluble in water). We see here a clear 

 distinction made between the carotin derivatives, corresponding 

 to 2, and the flavone and flavonol derivatives, to 3, both of which 

 occur as yellow flower pigments. These authors considered 

 that (1) and (3) were in no way related to each other, for 

 although they almost invariably found (3) occurring in flowers 

 containing (1), they never observed a blue flower turn yellow, 

 nor a yellow flower turn blue. 



Filhol (Compt. rend. 39, 194; Jonrn. f. pr. Chem. 1854, 63, 

 78) investigated qualitatively a large number of flowers, and 

 confirmed previous workers' observations that yellow pigments — 

 for which he retained the name Xanthogen (cf. Hope)— were 

 present, not only in yellow and white, but also in red, purple, 

 and blue flowers. He concluded that, with some few exceptions, 

 all the red, purple, and blue pigments were derived from the 

 same anthocyan. He examined the decolourisation of antho- 

 cyans in solution, and, finding that the addition of any acid 

 caused the reappearance of colour, concluded that the decolouri- 

 sation could not be the result of a reduction as suggested by 

 Fremy and Cloez ; in his opinion it was due to the mixing of the 

 pigments with other contents of plant cells, from which they 

 were kept apart in the living plant. 



Martens in 1855 (cf. Jahresber. 1855, 657) attacked the 

 problem from another point of view, attempting to elucidate tho 



