462 Comparative Vegetable Chromatology. [0(5lober, 



terised by the presence of yellow chlorophyll and yellow 

 xanthophyll, as well as by the absence of chlorofucine, 

 fucoxanthine, and the substances specially characteristic of 

 the red group. Blue chlorophyll and orange xanthophyll 

 are common to all, and it is probable that no class of plants 

 except fungi is ever quite free from both of them. It will 

 also be seen that the red group is intermediate between the 

 olive and the green, and independent of the colouring 

 matters specially characteristic of the red, it differs from 

 each of the other groups far less than they do from one 

 another, and, besides this, there are still closer connecting 

 links, not shown in the table. 



My endeavour has been to extend such a method of com- 

 parison to all the leading classes of plants and some of the 

 lower classes of animals, and to ascertain the order in 

 which they should be arranged, so as in like manner to have 

 the most gradual and unbroken passage from one to the 

 other. Comparing these various groups of Alga with other 

 classes of plants, and with such low classes of animals as 

 Actinia, I found that the whole of the colouring matters 

 present in the green Alga are those most characteristic of 

 all the higher plants, the only difference being that in 

 certain circumstances these latter contain in addition various 

 more or less accidental substances belonging to the erythro- 

 phyll and chrysotannin groups, which to some extent appear 

 to be characteristic of particular classes. As far as colour- 

 ing is concerned, the green Algce. are therefore perfectly 

 typical plants. On the contrary, the olive Alga differ from 

 them in a very marked manner. They contain no yellow 

 chlorophyll, or either of the two kinds of xanthophyll, all 

 three so very characteristic of the most perfect plants, but 

 contain chlorofucine and fucoxanthine, both of which are 

 found in certain species of Actinia, like Anthea cereus, var. 

 smaragdina. The presence of such colouring matters, there- 

 fore, connects them with some of the lowest classes of 

 animals, in the same manner as the presence of chlorophyll 

 connects such animals with plants. 



I have extended this method of comparison to many 

 other cases, but much remains to be learned before the 

 exact connexion of all the leading groups of plants can be 

 looked upon as established in a satisfactory manner, and I 

 have hitherto been unable to obtain suitable material for 

 thoroughly investigating the. relation between the lowest 

 classes of plants and animals. Though I look upon my 

 present results only as a beginning of the subject, it may, 

 perhaps, be well to explain what is the general bearing of 



