8 2 OYSTERS, AND ALL AP.OUT THEM. 



Fishermen say that if the water is clear where these 

 creatures are lying in their beds, they may be seen to close 

 their shells whenever the shadow of a boat passes over 

 them. The muscular borders of the mantle, especially, 

 are irritable ; they are, in fact, adapted to withdraw 

 themselves from hurtful impressions, and by pulling the 

 associated tendons against the central muscle, this also 

 becomes excited, and the oyster immediately closes its 

 shells. 



Attention is sometimes directed to a " little wonder." 

 We remember, for instance, an ingenious mechanic con- 

 structing many year's ago, a working steam-engine, the 

 packing-case of which was a walnut shell. A visitor who 

 was looking at it, finding it suddenly stop, inquired the 

 cause, when the engineer replying that the safety-valve 

 was not quite right, he exclaimed, in astonishment : 

 " Safety-valve ! I have not yet been able to see the fly- 

 wheel!" 



We have heard of mechanism still more minute. Yet, 

 let the smallest machine ever constructed be produced, 

 and it shrinks into abject insignificance when compared 

 with " Silver-shell" (the oyster) which had all the organs 

 now described, when as a tiny drop it alighted on the rock 

 where, for a time, it was to live and grow. Yes ! even 

 then did that vitalised atom inhale the air, select its 

 appropriate food, swallow it, digest it, and derive nutriment 

 from it, while the liver rendered its essential service, and 

 the aerating organs purifying the blood, the heart urged the 

 little stream through all the vessels of the oyster's frame ! 

 The mighty ocean, as its waves rolled over it, was subser- 

 vient to its life and its pleasures. The billo'ws wafted fresh 

 and choice food within its reach, and the flow of the 

 current fed it without requiring an effort ; while every atom 



