i&73'~\ Comparative Vegetable Chromatology. 461 



also distinguished by their colouring matters, than the leading 

 divisions of marine Alger, viz., the olive, the red, and the 

 green. These very seldom contain accidental colouring 

 matters, and the result is that the general colour is such a 

 good indication of the kind and relative proportion of the 

 fundamental colouring matters that it has been generally 

 recognised as a valuable means for arranging Alga into the 

 above-named three divisions, though the true relations and 

 differences were unknown. The total number of the funda- 

 mental substances is about twelve, and for a description of 

 their distinguishing characters I refer to my paper, recently 

 published in the " Proceedings of the Royal Society " 

 (vol. xxi., p. 442). # 



Now these various substances are distributed very dif- 

 ferently through the different groups, so as to connect: and 

 yet distinguish them in a very definite manner. I have not 

 been able to make accurate quantitative analyses, and, 

 besides that, there is a considerable variation in the relative 

 quantity of some of the constituents of the red group, and 

 therefore it is only possible to give a general tabular view, 

 by expressing the relative amount of the various substances 

 by means of the following signs : — 



A relatively large quantity .... % 

 ,, ,, moderate ,, . . . . + 

 „ „ small ,, 



Olive Red Green 



Group. Group. Group. 



Blue chlorophyll + + % 



Yellow chlorophyll .... + 



Chlorofucine + • 



Orange xanthophyll .... + + + 



Xanthophyll + + 



Yellow xanthophyll .... + 



Fucoxanthine % . 



Lichnoxanthines • + 



Phycocyan + 



Pink phycocyan % 



Red phycoerythrine .... -# 



On inspecting this table it will be perceived that the olive 

 Alga are characterised by the large amount of chlorofucine 

 and fucoxanthine, and by the total absence of yellow chloro- 

 phyll, of xanthophyll, and of yellow xanthophyll. The red 

 Alga are especially distinguished by the colouring-matters of 

 the phycocyan and phycoerythrine groups, but also differ 

 from the olive in containing xanthophyll and only a little 

 chlorofucine and fucoxanthine. The green Alga are charac- 

 vol. in. (n.s.) 3 o 



