THE INFLUENCE OF ANIMAL LIFE ON LIME. 93 



noxious influence of caustic lime, they are also 

 agents in the hands of the Almighty for other 

 purposes. Take up a handful of the sand cast 

 up by the retreating tide upon the adjoining 

 beach, and with a magnifying glass examine it 

 minutely; count the various objects you will see 

 there, and if you have sufficient patience, count 

 their numbers also : but it will be no easy task. 

 You will see how innumerable are the forms in 

 which very small shells will present themselves, 

 all of them delicate in their structure and ele- 

 gant in their shape, and inhabited by exquisitely- 

 formed creatures, having all the functions of those 

 found in larger shells. Monsieur D'Orbigny, a 

 great observer of these minute shells, reckoned 

 3,840,000 in one ounce of sand ! If we attempt 

 to calculate the contents of a square yard, the 

 amount would surpass all human conception. So 

 incredible are their numbers that they form 

 banks, which, by their accumulation, interrupt 

 the progress of ships, stop up bays and straits of 

 the sea, fill up harbours, and with corals pro- 

 duce those islands that rise up in the Pacific 

 Ocean. But do not start when I tell you that 

 these almost invisible living objects have been 

 employed in building up the very world on 



