PLANT LIFE 141 



is always destitute of organs of reproduction, 

 and it is believed that it grows vegetatively, 

 although this has been disputed. It is sup- 

 posed that the older patches gradually lose 

 their power of floating, and perish by sinking 

 in deep water. Attached forms of Sargassum 

 with reproductive organs have been found at 

 Bermuda, at the West Indies, and on the coast 

 of Central America. The floating masses 

 of Gulf Weed are believed to be continually 

 replenished by additional supplies torn from 

 the coasts by waves and carried by currents 

 until they accumulate in the great Atlantic 

 whirl which surrounds the Sargasso Sea. 

 They become covered with white patches of 

 polyzoa and serpulae, and quite a large number 

 of other animals (small fishes, crabs, prawns, 

 molluscs, etc.) live on these masses of weed 

 in the Sargasso Sea, all exhibiting remarkable 

 adaptive colouring, although none of them 

 belong properly to the open ocean. 



The red algae present two very different' 

 types. The one is soft and delicate, with 

 extremely fine ramifications, like the Poly- 

 siphonia of the English coasts. The other 

 grows in round masses, or with- ramifications, 

 always encrusted with calcareous matter. 

 These are the corallines (Nullipores), which 

 play a great role in tropical water, some forms, 

 like Lithothamnium, making up a large part 



