Ill 
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^e 
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 
