7IO HUBER. [Vol. XI.. 



their tortuous course, only short segments of axis cylinders are 

 met with. Many are lost in the connective tissue surrounding 

 the nerve trunk, and do not reach the peripheral ulnar. With 

 one of the nerves a small portion of the striped muscle tissue, 

 a part of one of the forearm flexors, on which the ulnar rests 

 just above the elbow, was removed. In sections through this, 

 several small bundles composed of six to eight nerve fibres, 

 having a very tortuous course, were seen in the endomysium 

 between the muscle fibres. I attribute the conditions here met 

 with to the fact that before the down-growing axis cylinders of 

 the central end reach the peripheral wound, the developing 

 connective tissue between the lower end of the implanted por- 

 tion and the peripheral ulnar has already become quite firmly 

 organized, and offers much greater resistance to the down- 

 growing axes than does the connective tissue of the central 

 wound which, at the time when the new fibres are first seen, 

 is more embryonic in its character. For it will be remem- 

 bered that in the experiments, where twenty-one days inter- 

 vened between the implantation and the removal of the nerve, 

 a few newly formed axis cylinders were found in the connective 

 tissue layer between the central stump and implanted nerve. 

 Beyond this no new fibres were observed, and by the end of the 

 thirty-ninth day after the operation the greater number of the 

 new axis cylinders had passed the central wound, and could be 

 traced a shorter or longer distance into the implanted nerve, 

 while only very few are seen in the lower wound and central 

 end of the peripheral ulnar. 



Still another interesting fact is shown in teased preparations 

 and longitudinal sections of the peripheral ulnar, and of the 

 muscular branches to the flex. carp. ul. in the above experi- 

 ments. The preparations show that the regenerated fibres are 

 found in larger numbers in the central end of the peripheral 

 stump and the muscular branches, the proportion becoming 

 much smaller in sections made from the peripheral part of the 

 nerves. In two of the experiments (Nos. 19 and 20) no axis 

 cylinders are seen 2 ctm. below the middle of the forearm ; 

 while in Exp. 17 very few were present in the ulnar at the 

 wrist. Teased preparations show that some of the regenerated 



