accompanying Chlorophyll, and their Spectroscopic Relations. 183 



carbon bisulphide and benzoline portions being coloured green, and 

 the alcoholic portion in each case yellow. I believe from the few ex- 

 periments I have so far made by these methods of separation, that the 

 xanthophyll, as I have defined it, passes along with the chlorophyll 

 into the carbon bisulphide or the benzoline, a point overlooked by 

 Kraus, but noticed by Sorby, while the alcoholic portion contains yet 

 another yellow colouring matter or matters, showing ill-defined absorp- 

 tion bands in the violet region, but in different positions again to either 

 the bands of chrysophyll or xanthophyll. May be we have here the 

 xanthophyll and yellow xanthophyll of Sorby, * whilst probably my 

 xanthophyll corresponds to his orange xanthophyll. 



I hope after some further experiments by these means of separation 

 which I am now undertaking, to be able to throw some further light 

 upon the apparent complex nature of this group of accompanying 

 yellow colouring matters. 



The Spectroscopic- Relations of Chlorophyll, Chrysophyll, and Xanthophyll. 



The method of observing the absorption spectra by means of 

 photography is the same as I adopted in a former investigation, deal- 

 ing with chlorophyll and its derivatives,! quartz lenses and an Iceland 

 spar prism being used. The question whether the bands shown by 

 crude chlorophyll solutions in the violet region are due to chlorophyll 

 itself, or to an accompanying yellow colouring matter, has not so far 

 been answered in a satisfactory manner. Some observers consider them 

 due to the former, whilst others, the majority I believe, attribute them 

 to the latter. 



On inspection of the plate (figs. 1, 2, and 5), it will be seen that the 

 chrysophyll bands are shifted towards the red end of the spectrum 

 compared to those of crude chlorophyll, so that if chrysophyll pre- 

 exists along with chlorophyll in its alcoholic extracts, the bands of the 

 two spectra would overlap, so as to produce one broad band extending 

 from F to K|3 ; but in all the freshly prepared normal crude chlorophyll 

 extracts I have examined, I have never found this to be the case, the 

 three bands always being visible on proper dilution, with no indication 

 of those due to chrysophyll. 



We can therefore conclude that they are not due to chrysophyll, and 

 must assume that if chrysophyll pre-exists, its relative quantity com- 

 pared to chlorophyll must be small. In the xanthophyll spectrum, it 

 will be noticed (Plate 6, fig. 3) the first three bands do not coincide 

 with the chrysophyll bands, being shifted towards the ultra-violet, and 

 the spectrum is further distinguished by a fourth band situated between 

 K|3 and L, which is lacking in chrysophyll, the latter having the cha- 



* ' Roy. Soc. Proc.,' vol. 21, p. 456. 

 f 'Roy. Soc. Proc.,' vol. 63, p. 391. 



P 2 



