BEPRODUCTION OF LIMBS. 



18o 



Most crustaceans are pugnacious in character, 

 and it often happens that when they fight, they 

 inflict serious injury upon each other's limbs; 

 and in such cases the maimed limb is detached, 

 not at the wounded spot, but at the joint imme- 

 diately above, and after awhile a slight protrusion 

 opens itself at the amputated joint, which pro- 

 trusion becomes more protruded, and in short 

 space develops into a limb. It is a very common 

 circumstance to find a lobster with one very large 

 claw, while the other is of comparatively small 

 size. There is a very wise object in this power. 

 The blood vessels of the crustaceans are but 

 slightly contractile, and, in consequence, if a 

 wound is inflicted, the vessels continue to bleed 

 freely. But by this amputation the wounded 

 surface is reduced to a very small portion, and 

 the substance of the joint contracts with sufficient 

 force to stop the bleeding. 



The shell of these creatures is formed of un- 

 yielding calcareous substance; and although it 

 may be a most excellent defence for the full- 

 grown crab or lobster, it leaves no room for 

 growth. In order to obviate this difficulty, the 

 crustaceans are possessed of the power of dis- 

 carding their shells at certain seasons of the year ; 

 at which time, also, a new and largfer shell is 



