46 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



proportion of cases such a mutilation resulted in the death of 

 the starfish it is impossible to decide, but an examination of 

 any considerable number of specimens, especially of the common 

 starfish, Asterias forbesi, will show how futile are any efforts to 

 destroy the animal merely by tearing it in two, for many in- 

 dividuals will be found in the process of regenerating one or more 

 missing arms. 



Such specimens indicate the readiness with which, under 

 favorable circumstances, the starfish may repair its injured 

 tissues, and replace one, two, three, or even four lost or muti- 

 lated arms. In fact, when carefully protected and fed in an 

 aquarium, the disk alone, deprived of all five arms, may slowly 

 regenerate all the missing parts. 



If an arm be pulled forcibly from the disk, it often happens 

 that a portion of the disk is removed with the base of the arm. 

 If the arm be badly mutilated and not removed, it is usually 

 thrown off by the spasmodic contractions of the muscles at a 

 certain point immediately outside the disk. Very strong chemi- 

 cal or electrical stimuli may cause the same result. 



This power of autotomy is doubtless of much importance to 

 the starfish, which can thereby stand a chance of escaping with 

 some of its arms when an enemy has seized one or more. Cer- 

 tain species living in other parts of the world, habitually re- 

 produce themselves by this method of fission, although none of 

 our native species multiply in this manner. In our species the 

 disk alone can restore the arms, but a single arm cannot restore 

 the disk. 



Nevertheless it should be emphasized that whenever a star- 

 fish is mutilated from any cause it becomes at once more sus- 

 ceptible to the attacks of its enemies, the injured surface furnish- 

 ing a vulnerable point, from which the protruding soft tissues 

 may be seized by fishes, crustaceans, and other creatures. The 

 whole body may be destroyed before the wounded surface has 

 healed. 



An arm removed from the body of a starfish may live for 

 several weeks if protected from the larger carnivorous animals, 

 but will eventually die without regenerating the rest of the body. 



But the disk from which one or more arms are missing will, 

 if not destroyed by fishes or other enemies, immediately begin 



