No. 6.] LIABILITY TO INJURY, 293 



abdominal appendages were found, it maybe that these append- 

 ages are sometimes lost. 



Shall we find, then, in the regeneration of these different 

 appendages any correspondence between the power of regener- 

 ation and the liability to injury or loss of a part? 



III. EXPERIMENTS ON REGENERATION. 



Two series of experiments were made, one lasting through 

 parts of June and July and another in August and September. 



The crabs, after the removal of one or more appendages, 

 were kept in aquaria with running water. They were fed 

 every day or two. 



In the first series of experiments the following operations 

 were made: From one series one or more of the walking legs 

 were removed on June 12. On July 2 the ten crabs were killed 

 and examined. 



(1) The right and the left first legs were both beginning to 

 regenerate. The tip of a second and of a \hird leg had been 

 cut off, but had not regenerated. 



(2) The right first leg had a new bud. 



(3) The right first leg had a long new part. 



(4) The left first leg had a moderately long new part. 



(5) The right first leg, removed very close to body, had not 

 regenerated, nor had the tips of the third and fourth legs that 

 had been cut off. 



(6) The right first leg and the third left leg had not regener- 

 ated (very small individual). 



(7) The first right leg had a very little (if any) new tissue, 

 and the left second leg had a long new part. 



(8) The left second leg and the right second and third legs 

 had long new parts. 



(9) The left second leg had regenerated a small new part. 



(10) The tip of the left third leg had not regenerated. 

 Summary. - - In three cases the leg had not regenerated; in 



one of these the leg had been cut off very near to the body, and 



in the other two cases two legs of the same crab, presumably 



.thrown off after injury, had not regenerated. Seven new legs 



