THE INFLUENCE OF THE NERVE ON THE RE- 

 GENERATION OF THE LEG OF DIEMYCTYLUS. 



CECIL SHEPARD HINES. 



The following experiments were carried on at the suggestion 

 of Professor Morgan, for the purpose of ascertaining whether 

 regeneration in the leg of Dicinyctyhts is dependent on its con- 

 nection with the nervous system, as has been found in the case 

 of other urodeles, or whether the supposed result may not have 

 been due to unintentional injury to the blood supply. The hind 

 limb was chosen for operating on account of its larger size. The 

 general course of procedure was to cut the nerve in the upper 

 part of the leg without injury to the artery, and then amputate the 

 leg at the knee joint. After a period of a little more than three 

 weeks the new part can be clearly recognized as a dark protu- 

 berance sharply contrasting with the lighter color of the sur- 

 rounding skin. 



In the first lots the nerve was cut as near the proximal end of 

 the femur as possible. A longitudinal slit through the skin was 

 made with a sharp knife. The muscles were then separated 

 until the nerve was brought into view. Care was taken not to 

 injure the blood vessel which closely adheres to the nerve and is 

 almost inseparable from it. If the operation were performed 

 without injury to the blood vessel and the leg showed a result- 

 ing paralysis it was amputated at the knee. For comparison an 

 equal number of salamanders had the leg cut off without injuring 

 the nerve or blood vessel. The results obtained from the first 

 series seemed to show that regeneration in Dicmyctylus was in no 

 way dependent upon the nerve. The proliferation of new ma- 

 terial began as soon in those in which the nerve had been cut as 

 it did in the checks. Nor did the amount of material regener- 

 ated seem to be affected in any way. There were, it is true, 

 great variations in the rate of regeneration, but these seemed to 

 arise from purely individual differences, and to bear no definite 

 relation to the presence or absence of the nerve connection. In 

 two checks operated upon on the same day and kept in the same 



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