THE AIALE 201 



not only by the elaboration of their reproductive 

 arrangements, but by their whole structure. Some 

 members of the order bear perfectly distinct and well- 

 formed leaves, and rival the flowering plants in the 

 perfection of their external morphology. This is the 

 case notably in the genus Sargassum, of which everybody 

 has heard, from the fact that the plant forms prodigious 

 floating masses, in the mid-Atlantic, giving its name to 

 the well-known Sargasso Sea, which is many thousands 

 of square miles in extent. In anatomical complexity 

 also we have seen that even Pelvetia approaches the level 

 of the vascular plants. It is well to realise at once that 

 Algae may attain a very high organisation. On their own 

 independent lines some of them have reached a degree of 

 differentiation not much inferior to that of the higher land 

 plants, with which, however, they have no direct relation- 

 ship. 



C. THE RED ALG^E (Floridece) 



The great majority of the red group of Algae are 

 seaweeds, though some genera are limited to fresh-water 

 streams. The marine Florideae, though they do not 

 reach the great dimensions of some of the brown 

 seaweeds, are well known to every observer, owing to 

 their beauty of colour and form, and are always 

 especially favourite objects with collectors at the seaside. 

 Most of them flourish rather low down on the shore, 

 especially frequenting the sides of deep rock-pools, while 

 many are only found growing beyond low-water mark. 



In these plants a red pigment, soluble in fresh water, 

 accompanies and usually disguises the green colour of 

 the plastids. The chlorophyll itself is similar to, but 

 not absolutely identical with, that of the higher plants. 



