CHAPTER VI. 



THE HOUSE THAT THE OYSTER BUILT. 



THE FIRST SHELL HOW TO TELL THE AGE OF AN OYSTER 

 WONDERFUL PROVISION FOR ITS GROWTH SECRETORY POWER 

 IRIDESCENCE THE ADDUCTOR MUSCLES CREATURES LIVING 

 ON SHELLS WONDERFUL TENACITY OF LIFE IN THE INFU- 

 SORIA AGENCY OF LIFE ANIMALS ATTACHED TO SHELLS 

 SECRETION OF CARBONATE OF LIME BY ANIMALS. 



THE oyster might properly be denominated its own archi- 

 tect and builder, even from the time when it first fell 

 from the briny waters on one of the rocks beneath ; for 

 not only was there a minute animal, but a covering for it 

 of two valves, or shelly plates, exquisitely adapted to its 

 comfort and security. All molluscs having shells, whether 

 univalve, like the limpet ; bivalve, like the mussel or the 

 oyster ; or multivalve, like the balanus, so plentifully scat- 

 tered over the rocks of our coasts, are similarly provided 

 for ; the minute creature having, at its first development, 

 a shelly covering of one or more pieces. 



But the oyster, as we have seen, grew rapidly, and 

 hence, were there no provision against it, serious evil 

 might arise. The accident of his house becoming too 

 small for him could not occur to the oyster. And why ? 



