186 



CHANGE OF SHELL. 



formed. This, in its turn, is cast off; and so con- 

 tinually, until the creature has attained its fiill 

 growth. Not only are the mere shelly coats of 

 the body and limbs thus changed, but the lobster, 

 for example, when it changes its shell, discards 

 with the shell the following portions of the 

 body : — 



The footstalks of the eyes. 



The external cornea of the eyes. 



The internal thoracic bones. 



The membrane of the ear. 



The membranous covering of the lungs. 



The tendons of all the claws. 



The lining of the stomach. 



And the stomachic teeth. 



The lobster seems to experience some difficulty 

 in casting its skin ; and from this list of organs 

 that are changed, it is but little wonder that there 

 should be a difficulty. 



There are certain glass toys that were once 

 much in vogue. A reel covered with thread, or 

 a model of a railway engine and tender, were 

 exhibited in a bottle with a very narrow neck. 

 The puzzle was, to discover how the reel got into 

 the bottle. But in the case of the lobster, there 

 is a puzzle of precisely an opposite character : for 

 it is easy enough to understand how a lobster 



