No. 3] PERIPHERAL NERVES. 731 



a band of nucleated protoplasm developed from the hypertro- 

 phied protoplasm and proliferated internodal nuclei of its 

 fibres, are met with) is the result of an outgrowth of new axis 

 cylinders from the undegenerated axes of the central stump, 

 the budding axis cylinders following the paths of least resist- 

 ance, through the tissue implanted or supplanting the implanted 

 substance, thus reaching the peripheral part of the resected 

 nerve wherein their growth continues. 



IV. Since the fibres in an implanted nerve segment degen- 

 erate so that only the collapsed sheaths containing a small 

 amount of nucleated protoplasm remain ; and the catgut 

 threads used in a suture a distance, and the bone tube 

 employed in a tubular suture, are almost entirely absorbed 

 before regeneration from the central end has reached any 

 degree of prominence, we must conclude that the implanted 

 substances can serve only as a guide to the down-growing axis 

 cylinders. Any further function cannot be ascribed to them, 



V. That the degenerated fibres of an implanted nerve 

 segment offer much more favorable mechanical conditions to 

 the down-growing axis cylinders of the central stump than 

 does the loose connective tissue supplanting the catgut threads 

 or the bone drain in experiments of suture a distance or tubu- 

 lar suture, is shown by the fact that the new nerve fibres have 

 a much straighter course and more regular arrangement in the 

 tissue uniting the resected ends of the injured nerve in such 

 experiments than in the case where the latter procedures are 

 made use of. 



VI. The above methods may be used in a primary operation 

 immediately after injury to the nerve, or as a secondary opera- 

 tion in cases when the operation is performed after a complete 

 or partial healing of the wound. The results are quite as 

 favorable in a secondary operation, although the return of 

 function takes place somewhat more slowly, 



VII. Making a nerve flap from the central or peripheral 

 stump is, for the following reasons, not to be recommended : 

 {a) The flap from the central end degenerates, and its connec- 

 tion with the central end does not prevent this ; {b) The 

 junction of the flap with the central end is a union not so 



