No. 3.] PERIPHERAL NERVES. 72 1 



the less developed connective tissue just below the central 

 stump offers less resistance to them than does the same tissue 

 at a later stage, it having attained a denser and more highly 

 organized structure. 



{c) SiiUire a Distance and Implantation of a Catgut Btmdle. 



Nearly all experimenters and operators who have studied the 

 regeneration of a peripheral nerve after resection or after loss 

 of substance to the extent that an ordinary suture cannot be 

 made, recognize the necessity of establishing between the 

 divided ends of the nerve a path along which the regenerated 

 fibres may grow. As has been previously stated, Gliick im- 

 planted strands of Danish leather, strips of muscle and tendon, 

 bone tubes, catgut bundles, etc., thinking that the implanted 

 substance might guide the new nerve fibres, and cause them to 

 grow in the direction hoped for. Gliick met with failure in all 

 of the above experiments. That regeneration may be attained 

 after the use of a tubular suture, is shown by the recorded 

 experiments of Vanlair, Bunger, and myself. The same may 

 be said of the results obtained by Assaky after suture a 

 distance with chromatized catgut. In the six experiments 

 reported by him, in which this method was employed, regener- 

 ation of the peripheral end occurred in each case. In the 

 seven experiments of suture a distance made by myself, the 

 physiological examination (for details see Part II) showed a 

 regeneration of the peripheral part of the divided nerve, in two 

 out of three experiments observed for a period of more than 

 120 days after the operation. That the catgut threads play 

 only a secondary part in the regeneration is shown by a micro- 

 scopical examination of the nerves involved in Exps. 35, 

 36, and 37, of five, ten, and twenty days' duration. In sections 

 made through the region of the catgut bundle, it will be seen 

 that the implanted threads begin to be absorbed before the end 

 of the fifth day, and are almost entirely absorbed by the end of 

 the tenth day. The connective tissue about the implanted 

 threads is seen in active proliferation in the immediate neigh- 

 borhood of the bundle, and betv/een its component threa.ds 



