No. 3-] PERIPHERAL NERVES. 719 



In Exps. 31 and 33 (resection and tubular suture of the 

 ulnar), of 121 and 136 days' duration, there was a slight 

 return of functional activity to the peripheral end, as stimula- 

 tion of the ulnar just below the peripheral wound excited 

 reflexes, but no muscular contractions. Histological examina- 

 tion of these nerves shows new nerve fibres in the upper end 

 of the peripheral stump, a larger number in the connective 

 tissue between the resected ends of the nerve, where their 

 number is inversely proportional to the distance below the 

 lower end of the central nerve trunk. The peripheral ulnar, 

 from a point 3 ctm. below the lower wound to the wrist, was 

 divided into short pieces. Alternating segments were used for 

 longitudinal and cross-sections. In none of the sections made 

 were any axis cylinders found. 



To determine whether the bone tube might be employed as 

 a secondary operation, in cases where there was loss of nerve 

 substance, a right ulnar of a dog was resected to the extent 

 of 6 ctm., and the wound closed (Exp. 34). Forty-one 

 days later the nerve was again exposed, and, after vivifying 

 the ends, a tubular bone-drain suture made. Longitudinal 

 sections of the segment removed from the central part of the 

 peripheral stump, only showed degenerated fibres in the form 

 of collapsed sheaths containing a small amount of nucleated 

 protoplasm. Presumably the entire peripheral part of the 

 nerve presented the same structure at the time of the second 

 operation. The central end of the nerve was seen to end in a 

 large bulb. The microscopical appearances presented by this 

 nerve 155 days after the second operation may be thus briefly 

 stated : A second bulb had formed on the end of the central 

 stump, beyond which a large number of small bundles of nerve 

 fibres were found in the connective tissue just below the bulb. 

 Cross-section of the cicatricial tissue just above the central end 

 of the peripheral part of the resected nerve shows that a 

 relatively small proportion of the nerve fibres found higher up 

 had reached this region, as only a small per cent of these is 

 met with in such sections. Regeneration extends to about the 

 middle of the forearm, and to the muscular branch of the flex, 

 carp, ul., although only a very small number of axis cylinders 



