3 o THE LIFE OF CRUSTACEA 



bloodvessels pass. When the limb is cast off, this 

 small opening quickly becomes closed by a clot of 

 blood, and further bleeding is stopped. If, as some- 

 times happens, a limb which has been seriously 

 injured is not cast off, the animal not infrequently 

 bleeds to death. This power of self-mutilation or 

 autotomy, as it is called, is frequently used by Crus- 

 tacea as a means of escaping from their enemies, 

 and is closely connected with the power of regenera- 

 tion of lost appendages. Beneath the scar which 

 forms on the stump of a separated limb a sort of 

 bud grows, and gradually assumes the form of the 

 lost segments. At the next moult this straightens 

 out, and, increasing in size at succeeding moults, it 

 ultimately provides, in normal cases, a new member 

 similar in every detail to that which had been lost. 

 Occasionally it happens, under circumstances not 

 yet altogether understood, that the process of re- 

 generation may, so to speak, go wrong, and in this 

 way various malformations and abnormalities result. 

 For instance, it has been found that, if the larger, 

 crushing claw of a very young Lobster be removed 

 by operation or by accident, the limb which grows 

 in its place may assume the form of the smaller, 

 toothed claw. Further, in some other Crustacea 

 (but not in the Lobster, except in the very youngest 

 stages), it is found in such cases that, after removal 

 of the large claw, the claw of the other side assumes 

 at the next moult the form of a crushing claw, so 

 that there is a " reversal of asymmetry." 



