326 TOILERS IN THE SEA. 



each lies in its proper place, and the whole is lined with 

 the slightest silken coating. The sand, being collected 

 at the orifice of the tube, its tenant, chiefly by means 

 of the tentacular organs, selects those which are 

 appropriate, and applies them to use. This is done 

 only through the night, all the additions being made 

 at the orifice, and as the animal grows, the shape and 

 dimensions of the tube result from the successive 

 growth of the body." 1 Pallas says that the tube 

 stands immersed in the sand, in a perpendicular posi- 

 tion ; and indeed the worm is very helpless when it 

 is laid horizontally. When at ease, and covered with 

 the water, it protrudes from the wide aperture of the 

 tube, the head with its four cirrhi, the comb of 

 bristles, and its many tentacles. The latter are 

 in continual movement ; they are shortened, and 

 lengthened, and twisted about at will, in search 

 seemingly for fit grains of sand ; and as the grains 

 adhere, by a gluten secreted from the surface, they 

 are carried within reach of the other organs, by 

 means of which the worm applies them to the rim 

 of its tube, and thus carries the structure upwards. 

 The tube is only increased by addition to this 

 end ; the posterior is plugged with the abdominal 

 appendage, and undergoes no material alteration. 



1 Sir J. G. Dalyell, " Powers of the Creator," &c., vol. ii. 

 p. 178. 



