90 POPULAR GEOGRAPHY OF PLANTS. 



usefulness than for its gigantic size. Like many other sea- 

 weeds, it has always been regarded amongst seamen as a 

 kind of natural buoy, which "often proves his unerring 

 guide towards land," and shows him the direction of the 

 currents with equal certainty. The Macrocystis performs a 

 still more important service even than this, " for it is, where 

 growing/' (as distinguished, that is, from floating pieces,) 

 "not only the infallible sign of sunken rocks, but every 

 rock that can prove dangerous to a ship is conspicuously 

 buoyed by its slender stem and green fronds ;" and it may 

 be safely affirmed, " that without its presence many channels 

 would be impracticable, and numerous harbours in the 

 South closed to our adventurous mariners." 



But we shall have formed a very inadequate idea of the 

 usefulness of the Macrocystis if we regard it only so far as 

 it is serviceable to man ; for " myriads of living creatures 

 depend on it for food, attachment, shelter, and means of 

 transport;" they themselves constituting "so extensive a 

 field of research, that the mind of the philosopher might 

 shrink from the task of describing them." 



As regards the distribution of the Macrocystis t it has 

 already been mentioned that its range extends from the 

 Antarctic to the Arctic Circle; but it is remarkable, that 



