THE RED PICxMEXT OF FLOWERIXG 

 PLANTS. 



GREEX is the fundamental note in the colour sym- 

 phony ot plants ; but red is of frequent recurrence. 

 The green colour is due to a mixture of pigments called 

 chlorophyll held in the meshes oi' protoplasmic bodies, 

 capable of growth and division, termed plastids ; the red, 

 ot the foliage of higher plants, is caused by a colouring 

 matter known inditterently as anthocyan or erythrophvll 

 which is dissolved in the cell sap. With another red 

 pigment, phycoerythrin, which gives the characteristic 

 colour to the group of alga^, the Florideas. and which is 

 associated with chlorophyll in the plastid, this paper is 

 not concerned. 



The part played by the green pigment chlorophyll in 

 the economy of plants is well known : but the ro/t of the 

 red colouring matter is obscure and the subject of much 

 guess-work. Since, however, some experimental researches 

 have recently been directed to the elucidation of the 

 question, it seems not inopportune here to summarise what 

 is known concerning the properties of this red colouring 

 matter. 



The colouring matters, soluble in water, which are 

 contained dissolved in the cell sap of many plants are, 

 by some, termed collectively anthocyan. or, more objection- 

 ably, erythrophyll ( i ) ; by others, they are referred to two 

 groups, the reds, blues and blue-greens to the Anthocyanin 

 or Cyanin (2) group ; the yellows and yellow-browns to the 

 Anthochlorin or Xanthein group. As will be seen, the 

 chemical nature of these pigments is unknown and conse- 

 quently any complicated terminology premature. Opinion 

 is divided as to whether the red and blue pigments are in 

 reality identical, the respective colours being due to acidity 

 or alkalinity of the cell sap, or whether they are difterent 

 chemical bodies. Krukenberg, (3) in his comparative 



