NOTES ON REGENERATION. I/I 



regenerated before the next moult. In practice, however, it is 

 not possible to cut the nerve without cutting also the blood-ves- 

 sels, and the injury to the latter may be as important as, or even 

 more so, than that to the nerve. 



The experiments were carried out with the hermit-crab and 

 with the fiddler-crab, but were unsuccessful in both cases for dif- 

 ferent reasons. First, the transposition does not occur under any 

 circumstances in the hermit-crab, as this and other experiments 

 showed ; and second, in the fiddler-crabs the muscles, etc., be- 

 yond the breaking joint degenerate after the operation. This 

 caused the death of most of the crabs, and those that remained 

 alive had only the outer shell of the leg beyond the breaking 

 joint, and even this fell off in several cases. Since, however, the 

 operation can be carried out in the hermit-crab without the outer 

 part of the leg degenerating, it may be possible, in other forms 

 that have the power of transpositional regeneration (in Alphcns, 

 for example), to carry out this experiment successfully. 



In both the hermit- and the fiddler-crab I also tried the effect 

 of removing three of the walking legs on the same side of the 

 body as the big claw, leaving the big claw uninjured, in order to 

 see if the absence of the other legs might possibly affect the 

 transposition. This did not succeed, because in the hermit- 

 crabs, as I have said, the big claw does not throw over, and in 

 the fiddlers the experiment had to be brought to an end before 

 any of the crabs had moulted. 



All of the individuals of the hermit-crab that I have examined 

 were right-handed, and the shells in which they live have also 

 right-handed spirals. It has been suggested to me that this is 

 an adaptation, in so far that the right-handed hermit crab is 

 placed to better advantage in a right-handed shell. Conse- 

 quently, if this were true (and I am by no means certain that it 

 is so), it would be disadvantageous for the hermit-crab to have 

 the power of transposition after the loss of the big claw, and in 

 consequence this power has not been acquired, or else, if it ex- 

 isted in the ancestors "of the hermit-crabs, it has been lost. That 

 there is really no basis for an argument of this kind is shown by 

 the state of affairs in other decapods ; in the lobster, for example. 

 In the American lobster I have seen several cases in which the 



