560 ANNALS NEW YORK ACADEMY OF SCIENCES 



with a sharp blade and immediately sutured with silk. Each nerve 

 was allowed to regenerate for a determined interval, from 17 to 1363 

 days, and was then excised and placed on electrodes in a moist chamber 

 at 38° C. 



The regenerating fibers were able to conduct impulses after a very 

 brief regeneration period, and at 17 days, action potentials were re- 

 corded from the distal stump of one tibial nerve within a distance of 

 2 cm. from the suture. This potential was small, less than 10 micro- 

 volts in amplitude, and was conducted very slowly at a maximum of 

 0.9 meters per second. The potentials recorded from fibers which had 

 regenerated for longer periods were of greater amplitude and were con- 

 ducted at greater velocities. The increase in conduction velocity was 

 rapid in the first few days and, by 36 days, velocities of 17 m.p.s. were 

 recorded, as shown in plate 5 A. This record was taken from a mono- 

 polar electrode placed 3.5 cm. distal to the suture, and shows a maxi- 

 mum conduction velocity of 17 m.p.s. and a spike amplitude of 25 

 microvolts. The maximum conduction velocity continued to increase 

 with the time allowed for regeneration, but at an ever-decreasing rate 

 of recovery. Thus, at 50 days, 25 m.p.s. were attained; at 100 days, 

 40 m.p.s.; at 200 days, 60 m.p.s.; at 365 days, 70 m.p.s. Beyond 544 

 days, no further recovery of conduction velocity was found, and at the 

 long period of 1363 days, only 80 m.p.s. were attained. The record in 

 PLATE 5 C was taken from the distal stump of a tibial nerve 1363 days 

 after suture, and can be compared with the record from the opposite, 

 normal, tibial nerve of the same animal in plate 5 B, in order to deter- 

 mine the degree of recovery. In plate 5, B and C, the conduction dis- 

 tance was 8 cm., but in the record from the regenerated nerve, the dis- 

 tance or time between the shock artifact and the beginning of the spike 

 is greater than in the normal record, and shows that the 80 m.p.s. repre- 

 sent less than 80% recovery toward the normal conduction velocity. 

 Similar results were obtained from the peroneal and saphenous nei'ves. 



Two other observations can be made from plate 5, B and C. Firstly, 

 the amplitude of the spike is less in the regenerated nerve, and secondly, 

 the spike in plate 5 C is not as complex. The lack of recovery of all 

 the components of the spike was even more obvious in records from 

 the saphenous nerves, where the normal potential is more complex and 

 consists of a double or triple peaked alpha wave and distinct beta, 

 gamma, and delta waves. Even after long periods of regeneration, the 

 saphenous nerve did not recover these wave components and showed 

 only an initial peak which leveled off into a long tail. 



