Ai'R. 1896.] BOTANICAL SOCIETY OF EDINBURGH. 541 



skin gives a reddish orange solution in alcohol, and a pure 

 yellow one in petrol-ether, while it undoubtedly forms a 

 sodium compound. It thus falls into neither of Zopf's 

 classes. So far as my own experience goes, the question 

 as to the formation of sodium compounds is much more 

 complicated and more dependent upon the method employed 

 than is apparent from Zopf's statements, and, in con- 

 sequence, should not be too rashly employed for purposes 

 of classification. Por purposes of convenient reference the 

 following scheme of the common lipochromes of plants 

 may be suggested ; it is chiefly based upon the solubilities 

 in the various solvents as described above, and, therefore, 

 can be readily refuted or confirmed in practice. 



CLASSIFICATION OF PLANT LIPOCHROMES 



All give in dry state 



blue colouration 



with HjSO^ 



1st Series. 

 Colour yellow. All readily 



soluble in benzol and 



chloroform. 

 Not readily crystallised. 



Xanthophyll. 



Xanthiu. 



Phycoxanthin. 



,1 



2nd Series. 



Colour orange to red. All | Carotin 

 insoluble in cold alcohol, 

 but very soluble in ben- 

 zol and chloroform. 



Readily crystallised. 



Erytlirophyll(chrysophyll) 



Anthoxanthin. 



Clilororutin. 



The next great group of pigments which we sliall con- 

 sider includes these often known as the authocyan series, 

 which are soluble in water, and frequently produce very 

 conspicuous colouration. On account of their solubility 

 they occur in the cell-sap and not in chromatophores like 

 the lipochromes, which are often called fixed colours as 

 opposed to these fi^iid ones. Anthocyan, or the series of 

 pigments included under this name, occurs as a red, blue, 

 or violet colouring-matter, and gives their colour to many 

 flowers and fruits, to some autumnal leaves {e.g. vine and 

 Virginian creeper), to the purple or " copper " varieties of 

 forest trees {e.g. beech), and to many plants or parts of 

 plants which, either habitually or as a variation, show a 

 red colour {eg. "runners" of strawberry plants, shoots of 

 rose, purple cabbage, etc.). The distinguishing character- 

 istic of these pigments, besides their solubility, is that they 

 vary in colon r according to the reaction of the solvent. 



