1873,] Comparative Vegetable Chromatology . 4i75 



xanthophyll, all so characteristic of the most perfect plants, but contain 

 chlorofucine and fucoxanthine, both of which occur in certain species of 

 Actiniae, like Antliea cereits, var. smaragdina. The presence of such 

 colouring-matters, therefore, connects the olive Algce with the lower 

 classes of animals, in the same manner that the presence of blue chlorophyll 

 connects some animals with plants. Such substances, though essential 

 to the growth of plants, are not constant in closely allied species of animals, 

 as though they were of no more importance for the life of animals than 

 the accidental vegetable colouring-matters are for the life of plants. The 

 value of these connexions between plants and animals remains to be 

 determined, but in any case such definite facts must, I think, have some 

 very important signification. If, then, according to these principles, the 

 olive Algce be looked upon as a link connecting the lowest classes of plants 

 with some of the lowest classes of animals, there is a perfect and simple 

 continuity ; whereas if they were to be considered intermediate between 

 green Algce and the higher Cryptogamia, there would be two great breaks 

 of chromatological continuity. 



Changes occurring in Oscillatorise. 



The olive Algce are also connected in another manner with lichens, 

 through Oscillatorice. These latter plants are extremely interesting, since 

 they are subject to most remarkable changes, depending on the conditions 

 in which they grow. I have made a series of quantitative analyses, which 

 show this in a striking manner. I may here say that the chief difficulty 

 in the analyses was the determination of the amount of the lichnoxanthines 

 in presence of chlorofucine and fucoxanthine, and therefore the quantities 

 given must be looked upon as only approximate, derived from several 

 different methods, none of which were perfectly satisfactory, though they 

 all agreed in leading to the same general conclusions. In discussing the 

 results of the analyses, it was requisite to take the amount of blue 

 chlorophyll as uniform, since it was the only constituent occurring in any 

 considerable quantity throughout the whole series. To have taken equal 

 weights of the plants themselves would have been almost impossible, and 

 would often have made those which really correspond very closely appear 

 to differ extremely, since the constitution of the endochrome is the im- 

 portant question. Of course by thus calculating the results as if the 

 amount of chlorophyll were the same in all, there appears to be an in- 

 crease in some of the other constituents in the specimens exposed to the 

 sun, due, however, in reality to a reduction in the relative quantity of 

 chlorophyll. 



For comparison I give the following : — 



I. Fucus serratus grown in the shade. 



II. The same plant grown in the sun. 



III. Oscillatoria grown under water, in a cold spring, in a very shady 

 place. 



