m THE COLOURS AND PIGMENTS OF PLANTS 57 



from the injurious effect of certain of the elements of 

 white light by absorbing them, or that it in some 

 way assists the assimilating action of chlorophyll. 

 As yet, however, there is little evidence for either 

 of these suggestions, and the majority of authors are 

 quite silent as to the function of xanthophyll. 



Colour in Alg^ 



A similar association of chlorophyll with other 

 pigments, especially lipochromes, is often well seen 

 in the Algae, where the pigments seem more varied 

 than in flowering plants. In many cases they com- 

 pletely mask the chlorophyll, while in others the 

 unequal distribution of the chlorophyll produces 

 colour effects which show a striking resemblance to 

 those seen in the flowering plants. 



The masking is especially well seen in the case 

 of the colouring-matter of the Florideae or Red Sea- 

 weeds, which has further had an important function 

 ascribed to it. These Algae for the most part live in 

 deep water, and are chiefly known to those who are 

 not botanists by the beautiful reddish-pink fronds of 

 Delesseria so often cast up on the seashore during 

 the summer months. Like Delesseria the Florideae 

 are nearly all red or violet when living, but if placed 

 in cold, fresh water the red pigment dissolves out 

 and leaves the seaweed green. The solution in 

 water of the red pigment, known as phycoerythrin, 

 fluoresces strongly from red to yellowish-green. The 

 chlorophyll with which it is associated in the Florideae 

 is said to differ in some respects from the chlorophyll 

 of other plants. Now, as we have said, the Red 



