270 Drs. Mott and Halliburton and Mr. Edmunds. [June 12, 



(2) Experiments on Transplanted Pieces of Nerve. 



We have already seen that Vulpian and Philippeaux transplanted pieces 

 of nerve under the skin of the abdomen, and observed in them what they 

 at first thought was evidence of auto-regeneration, a conclusion subsequently 

 withdrawn by Vulpian. Similar experiments, recently published by 

 Kennedy* are regarded by him as proving absolutely conclusively the auto- 

 genetic origin of nerve-fibres. He excised a portion of the sciatic nerve 

 and transplanted it into the subcutaneous tissues of the same animal. Six 

 months later he killed the animal and examined the nerve which had been 

 transplanted. He found among a number of degenerated fibres some which 

 were definitely formed with a medullary sheath showing distinct nodes of 

 Eanvier. He concluded that these fibres had been formed by the tissues 

 of the excised portion of nerve. 



He conceives objectors to this deduction maintaining that these nerve- 

 fibres have grown into the sheaths of the transplanted nerve from cutaneous 

 nerves divided in the course of the operation, and meets this objection as 

 follows : — 



" Such an explanation is, I think, far-fetched, and assumes an extraordinary 

 affinity between the supposed young nerve-fibres and the old nerve trunk, 

 an affinity which, if established, would, I am sure, secure almost certain 

 spontaneous union of nerve trunks after division, unless very extraordinary 

 barriers were placed between the divided ends. 



" The number of cases, however, in which secondary suture has to be 

 performed shows that divided nerves cannot be confidently left to nature 

 to repair, which I am sure might almost uniformly be the case did such 

 strong affinity between young nerve-fibres and the distal degenerated 

 segment exist." 



It has, however, been shown that a large nerve trunk on division curls up 

 at the end, forming a contorted leash of fibres. Further, a nerve trunk on 

 division retracts, and a considerable amount of scar tissue is formed. This 

 cicatricial tissue by the time the nerve has begun to regenerate has become 

 dense fibrous tissue. In the case of nerve trunks, therefore, " extraordinary 

 barriers" are the rule. Moreover, in spite of such barriers spontaneous 

 union often occurs, and in animals when the cut is made more cleanly than 

 occurs in an accident in man, and when antiseptics are used, the amount 

 of cicatricial tissue formed is less, and union may be confidently anticipated 

 without suture either immediate or secondary. In the case of small nerve 

 trunks the case is also different ; for example, after operations involving 



* 'Brit. Med. Journ.,' 1904, vol. 2, p. 729. 



