32 THE OCEAN. 



into oval bulbs or air-vessels. Boys amuse them- 

 selves occasionally by cutting off these nodules in a 

 diagonal direction, to make them into whistles. They 

 are too tough to be burst by the pressure of the fingers, 

 like those of the Sea-wrack ; but if stamped on, or 

 put into the fire, they explode with a loud report. 

 The seed-vessels are large, oval, and yellow, resem- 

 bling those of the last, placed on footstalks. 



One of the most common species of our coasts 

 is the long, string-lilvc Sea-lace, or, as the Orkney 

 people call it, Sea-catgut {Chorda filum). It usually 

 gi-ows in water some fathoms deep, attached to stones 

 at the bottom, yet reaching to the surface • indeed, it 

 sometimes attains the length of forty feet ; and this 

 is believed to be the growth of a single summer, 

 as it is an annual plant. Its structure is highly 

 curious ; at first sight it appears a simple cylindrical 

 tube of an olive colour, about as thick as whipcord, 

 but occasionally thicker : on examination, however, 

 this hollow stem is found to be composed of a flat 

 thin ribbon, about one-sixth of an inch in width, 

 spirally twisted into a tube, the edges exactly meet- 

 ins: each other, and adherincf with sufBcient firmness 

 to allow of the whole stem being skinned without 

 separating : in this state it is twisted and dried, when 

 it possesses a strength and toughness that adapt 

 it for fishing-lines. In Norway it is collected as 

 food for the cattle. The upper portion usually floats 

 on the surface, or rather immediately beneath it, 

 often in such abundance as to form large meadows, 

 as it were, which obstruct the progress of boats. 

 The fructification of this species long defied the 



