THE OYSTER. IQ 



what was the change, external to the oyster, which 

 excited the sense organs, and must ask how the oyster 

 has learned to associate such a sensation with the 

 presence of danger, and how it has learned that the 

 danger may be escaped by closing the shell. 



It is much more easy to ask this question than to 

 answer it. The oyster is by no means a simple animal, 

 and our efforts to study and understand its structure 

 bring us, at the first step, face to face with problems of 

 the most profound character; problems which will tax 

 all the resources of investigators and philosophers for 

 many generations. We will not, however, enter into 

 these deep questions, but will confine ourselves to 

 simpler matters. 



The muscle is attached to the shell at some distance 

 from the hinge, in order that it may have leverage and 

 work to advantage; and it must therefore be able to 

 move as the shell grows, for in an oyster three inches 

 long its area of attachment is outside what was the 

 extreme border of the shell when this was only an 

 inch long. The muscle travels by the addition of new 

 fibres on its outer surface, together with the absorption 

 and removal of those on its inner border. As it moves, 

 the old impression on the shell is gradually covered up 

 by new deposits of lime, and in an empty shell it may be 

 traced for some distance up towards the hinge, when it 

 gradually becomes more faintly marked, as the layers of 

 new shell grow thicker. A very good idea of the way 

 the shell grows and keeps pace with the growth of the 

 body, may be gained by the careful examination of the 

 muscular impression on its inner surface. Every fool 

 knows why a snail has a house, but the king could 



