482 M. J. GREENMAN 



forceps especially made for this operation have long slender jaws 

 on the inner surface of each of which at the extreme end is a 

 transverse groove so placed that when the j aws are brought to- 

 gether they present opposed depressions between which the wire 

 loop may be firmly clamped together without danger of slipping. 



In later operations the preliminary crushing of the nerve by 

 the bone forceps was omitted and the crushing done by clamp- 

 ing the wire hook on the nerve. No. 26 annealed silver wire 

 was used. 



The wire clamp was left on the nerve. In most cases the 

 wire clamp remained on the nerve and became embedded in 

 new tissue deposited about it. This new tissue formed a bridge 

 or capsule structure connecting the proximal end of the nerve 

 to its distal segment. This bridge was usually best developed 

 on one side of the ring while in some cases its development 

 formed a more or less uniform enclosure for the ring. Through 

 this connecting bridge the fibers of the regenerated nerve were 

 found to pass from the proximal to the distal segment of the 

 nerve. 



The animals selected varied in age from 31 days to 250 days 

 (adults) at the time of operation and they were permitted to 

 live from 3 to 105 days after operation. 



When the animal was killed, about 10 mm. of the operated 

 nerve, including the region of operation, was removed. An 

 effort was made to have an equal length of nerve on either side 

 of the clamping wire. About 10 mm. of the corresponding nerve 

 of the left side was also removed as a control. These specimens 

 were fixed in 1 per cent osmic acid, embedded in paraffin and 

 sectioned. All sections were cut seven micra thick. A few sam- 

 ple sections of the control side were mounted. The operated 

 (right) nerve was cut in continuous series and mounted, the 

 series beginning in the nerve above the point of crushing where 

 the nerve appeared to be normal, and continuing through the 

 region of operation into the new or regenerated nerve. The 

 sections of the operated or right nerve have been designated as 

 proximal or distal according to their relation to the point of 



