182 Mr. C. A. Schunck. The Yellow Colouring Matters 



case with chlorophyll ; while away from the light it can be kept for a 

 considerable time without any apparent change taking place in its solu- 

 tions. Alkalis which induce so great a change in chlorophyll appear 

 to have no action upon it. From chlorophyll solutions which have 

 been boiled with potash or soda, and from which animal charcoal will 

 not now absorb any appreciable amount of colouring matter, ether 

 takes up this yellow colouring matter unaltered. Likewise, if its 

 alcoholic solutions be boiled with an alkali, no alteration is discernible. 

 On the other hand, if hydrochloric acid gas be passed through its 

 alcoholic solutions the colour changes to a dull dark-red, giving no 

 bands, but a general obscuration in the violet and ultra-violet region 

 of the spectrum. By this method I have obtained this yellow colouring 

 matter from two species of Ficus, from parsnip, clover, birch, and 

 Virginia creeper leaves, the extracts of the last-named, when even 

 freshly prepared, showing a near approach to the phyllocyanin spec- 

 trum, I have also examined the yellow colouring matter of autumnal 

 leaves, and find that it is identical with it both in properties and 

 spectrum (Plate 6, figs. 3 and 4) ; but in autumnal leaves invariably I 

 find the presence of the other yelloAv colouring matter which obscures 

 the spectrum, but which can be got rid of by separating with ether. 

 This supports the belief that the yellow colouring matter of autumnal 

 leaves is what remains after the chlorophyll of the healthy green leaf 

 has faded away, the latter being the less stable of the two (as has already 

 been shown to be the case), and fading first. I have examined the 

 colouring matter of some etiolated leaves, and here the presence of a 

 yellow colouring matter that obscures the spectrum in the violet and 

 ultra-violet region is undoubted. I endeavoured to get rid of it, as in 

 the former experiments, by separating with ether, but seemingly with 

 only partial success, the ethereal portion showing only three bands, but 

 in the same positions as the first three bands of the yellow colouring- 

 matter under review, the rest of the spectrum in the violet and ultra- 

 violet being obscured. 



It is to this yellow colouring matter giving the characteristic spec-^ 

 trum of four bands in the violet region, a spectrum not before observed, 

 I believe, and which I believe to be the predominating yellow colour- 

 ing matter accompanying chlorophyll in ordinary green leaves, and 

 also of faded autumnal leaves, that I would restrict the name xantho- 

 phyll, just in the same way that phylloxanthin, from being first applied 

 by Fremy to include all the yellow colouring matters accompanying 

 chlorophyll, as well as a yellowish-brown decomposition product of the 

 latter, has been applied by Schunck in a stricter sense to one of the 

 group only — the yellowish-brown decomposition product of the action 

 of acids. Crude alcoholic chlorophyll solutions can, as before stated, 

 be separated into a green and yellow portion by agitating with carbon 

 bisulphide — Sorby's method — or by benzoline, Kraus's method, the 



