48 



M. Mohl justly doubts, on second thoughts, whether the 

 origin of the red cellular sap*can be explained in the cases 

 above-mentioned by a dissolution and change of the chloro- 

 phylle, as the green globules of the sap occur in the red sap 

 as beautifully coloured as in general. 



M. Berzelius * has examined the autumnal colour of plants 

 in a chemical point of view ; he only observed red leaves in 

 trees and shrubs whose fruits are red. However this does not 

 stand good for the whole vegetable kingdom, for M. Mohl and 

 many others have mentioned various plants in which red 

 leaves occur with fruits of a different colour. M. Berzelius 

 examined the foliage of the cherry tree, and especially that of 

 the red currant, which frequently appears as red as the ripe 

 berries. The colouring matter was extracted with alcohol, 

 which after distillation left behind a red fluid, that had first to 

 be filtered from the precipitated resins and fats. The colour- 

 ing matter is soluble in water, and agrees therefore probably 

 with the red substance which M. Marquart extracted from red 

 flowers, and declared to be an acidulated anthocyan. M. Ber- 

 zelius terms this red colouring substance Erythrophylle, Leaf- 

 red, and is opposed to the view of this red colour being only 

 an acidulated blue ; he found it however in the fruits of the 

 cherry tree and black currant, so that it is evidently closely 

 related to Marquart^s acidulated anthocyan. 



Of considerable interest are M. Berzelius' s observations on 

 the yellow colour of leaves in autumn; this substance does not 

 coincide with Marquart's anthoxanthin, but is a peculiar fat, 

 an intermediate body between fat oils and resins, which re- 

 taining its property of being of difficult solution in alcohol, and 

 smeary and greasy, may be bleached. He calls this substance 

 Xanthophylle, Leaf-yellow, and prepared it by cold infusion 

 of the yellow leaves in strong alcohol, continued for forty- 

 eight hours. When the infusion is evaporated to less than 

 one-eighth of the quantity, a granular substance settles on cool- 

 ing, and by continued distillation a yellow soft smeary sub- 

 stance is obtained, which, like the granules above-mentioned, 

 presents the colouring substance of the yellow leaves. The 



* Ueber die gelbe Farbe der Blatter im Herbste und iiber den rothen 

 Farbestoff der Beeren und Blatter im Herbste. Ann. der Pharmacie, vol. 

 xxi. p. 257264. 



