OYSTERS, AND ALL ABOUT THEM. 



continual friction, rub and wear down the rock, and file 

 away its substance. Other naturalists suggest that the 

 pholas may have the power of secreting a corroding 

 liquid, by which the rock is eaten away. But then, how is 

 the shell itself to escape the action of the liquid ? 



To De Blainville belongs the honour of suggesting 

 that a simple movement of the shell, constantly repeated, 

 would in time pierce the stone. Observation has since 

 decided that his opinion is correct ; the shell itself cannot 

 be worn away by this process, because it is composed of 

 aragonite, which is harder than the rock in which the 

 animal burrows. The mollusc bores down a considerable 

 depth, and then hollows out its home to accommodate its 

 increasing bulk. Hence their lithodomes are bottle- 

 shaped wide at the bottom, with narrow necks. These 

 little borers cannot but excite our wonder. Here are soft 

 creatures, without the slightest consistency, capable of 

 hollowing out for themselves homes in the hardest rocks ! 

 Such is the power of life, even in its lowest development, 

 over inanimate matter, (e) 



If the reader should have the opportunity, in some 

 ramble on the coast, let him strike the beach with a stick, 

 or only tread heavily, and he may, perchance, frighten a 

 pholas, and cause it to spirt water from its sandy dwelling, 

 and, thus apprised of its site, dislodge it as a prize. Let it 

 now be placed in a vessel of sea-water, and two currents 

 will be observed issuing with surprising force : the one 

 inhalant, and the other exhalant ; the former having an 

 orifice somewhat like a trumpet, exquisitely fringed, 

 carries into the body of the creature all the floating par- 



(e) "The World of the Sea," pp. 188-90. 



For further information, see the above : English Translation. 

 Cassell & Co., London. 



