414 HOMES WITHOUT HANDS. 



thaa that of the distance from one partition to another. The ar- 

 rangement of the tubes and the partitions looks very complicated, 

 but is, in fact, simple enough. The animal secretes around itself 

 the calcareous substance which forms the tube, but when it has 

 reached to its full extent, it is obliged to leave the cylindrical 

 home in which it had resided. The partition is then secreted by 

 the edge of the mantle, or membrane by which the creature is 

 attached to its tube, and the zoophyte then begins another tube 

 immediately above that which it has quitted. 



Sometimes there is a kind of floor that separates the upper tube 

 from the lower, but it is extremely thin, so that a tolerably stout 

 bristle can be pushed through it. The partition is at least twice 

 as strong as the tubes, which are scarcely thicker than the paper 

 on which this account is printed, and is not solid, but perforated 

 _with holes just like the machine-made bricks which have lately 

 come into use. In my own specimen there is a curious proof of 

 the abundance of submarine animal life. The group of Organ- 

 pipe Coral has enveloped a piece of White Coral, and has shown 

 a remarkable instance of the manner in which beings so low in 

 the scale of nature can accommodate themselves to circumstances. 

 As if conscious that the coral formed an obstacle which they 

 could not pass in a direct line, they ceased from tube-building 

 when they arrived within a little distance of the coral, and threw 

 up a partition vertically instead of horizontally, so as to envelop 

 the greater part of the coral with the red calcareous substance. 

 Having done so, they then made a new foundation upon the 

 coral, and built a fresh series of tubes, so that, when viewed from 

 above, the series of tubes is quite uninterrupted, and no one 

 would imagine that any extraneous substance had intruded into 

 the mass. 



The tubes themselves have formed the basis of other subma- 

 rine habitations, for a moderate magnifying-glass shows that sun- 

 dry molluscs and moUuscoids have settled down upon their ex- 

 terior, while the white serpentine tubes which creep among the 

 perpendicular pillars show that the serpulaa and other tube-mak- 

 ing creatures have taken up their residence in so well-protected 

 a spot. 



At the bottom of the sea there are a vast number of wonderful 

 and interesting animals that are known to naturalists as Tijhico- 

 bus Annelides, i e., Tube-inhabiting "Worms. These creatures are 



