No. 3-] PERIPHERAL NERVES. 729 



in the above experiments, the details of which are given in 

 the second part of this paper. The peripheral median stump, 

 which was stitched (grafted) to the accompanying ulnar 

 (Exp. 49), was found to be completely degenerated, and no new 

 axis cylinders or nerve fibres were to be found in the connec- 

 tive tissue uniting the central end of the peripheral part of the 

 median to the ulnar. The central median stump terminated in 

 a large bulb presenting the microscopical appearance usual 

 for such structures. The ulnar, to which the median was 

 grafted, was in no way altered structurally. 



In Exp. 50, in which, it will be remembered, the central 

 part of a resected median was sutured to the peripheral por- 

 tion of a resected ulnar (the segments exsected having been 

 taken from different levels in the two nerves), the microscop- 

 ical examination shows the peripheral part of the ulnar to 

 contain newly formed nerve fibres throughout its whole extent. 

 In longitudinal section through the junction of these two 

 nerves, the young nerve fibres found in the peripheral end of 

 the central median stump can be traced through a narrow layer 

 of connective tissue into the peripheral part of the ulnar. We 

 are, I think, justified in seeking the origin of regenerated 

 fibres found in the ulnar in the down-growing axis cylinders of 

 the central stump of the median, which had been sutured to 

 the peripheral part of the accompanying ulnar. 



So far this experiment is a confirmation of the results 

 obtained by other observers, and again proves that union with 

 return of functional activity after cross-suturing two spinal 

 nerves is possible. The short segment of the peripheral 

 median, which was grafted to the peripheral ulnar stump, was 

 completely degenerated ; in none of the sections made from it 

 were any new nerve fibres found. The central ulnar segment, 

 stitched to the central median stump, terminated in a large 

 bulb surrounded by connective tissue, by means of which it 

 was united to the median. This tissue was free from naked 

 axis cylinders or new-formed nerve fibres. 



Tillmanns' modification of Letievant's operation of cross- 

 suturing the long ends of two divided nerves having a parallel 

 course, when there is loss of nerve substance to the extent that 



