296 T. H. MORGAN. 



If it could be shown that the leg of amphiuma is a degenerate 

 structure it might appear that there is some connection between 

 the degeneracy of the part and its lack of power to regenerate, 

 but it is far from being established that any such general relation 

 really exists. In fact, in the male hermit crab I found that the 

 very small and apparently rudimentary abdominal appendages 

 have the power to regenerate. It would be interesting, never- 

 theless, to examine this point further in cases where the degener- 

 ation and uselessness of an organ are more certainly established, 

 as in the case, for example, of the appendix of man, which does 



not appear to have the power to regenerate after removal. 

 WOODS ROLL, MASS., June 22, 1903. 



