No. 3.] PERIPHERAL NERVES. 643 



author's experiments were decalcified in a one per cent solution 

 of hydrochloric acid, and thoroughly washed in flowing water. 

 It may be that this rapid absorption could in some degree be 

 retarded by decalcifying in chromic acid ; no practical test 

 was, however, made of this. 



(d) Suture a Distance. — Believing that a divided peripheral 

 nerve is regenerated through axis cylinders budding from the 

 central end, and recognizing the fact that it is necessary to 

 make it mechanically possible for the down-growing central 

 fibres of a resected nerve to reach the peripheral end, Assaky 

 tried experimentally to create such suitable mechanical condi- 

 tions by uniting the ends of a resected nerve with catgut 

 threads, expecting that these would guide the regenerating 

 fibres, and thus aid them in reaching the peripheral part of the 

 nerve. Assaky's experiments were of the following nature : — 



In an adult dog he resected 35 millimeters from the left sciatic, and 

 united the ends, which were fixed at a separation of 3 ctm., with four threads 

 of No. 3 catgut. The wound was closed with silver sutures, and a drain 

 was placed into the dependent part of the wound. The dog was killed 

 thirty-five days later. The nerve stumps were found united with a cord 

 somewhat smaller than the nerve itself. After cutting the nerve above the 

 seat of section and rubbing across the distal end, no contractions were 

 noticed. Compression of the nerve excited a single movement. When 

 stimulated electrically, the muscle would contract slowly, " contracting as 

 with regret." Histological examination revealed newly formed fibres in 

 the cord uniting the resected ends, some of which possessed a thin sheath of 

 myelin, others were naked. In the peripheral stump the old degenerated 

 sheaths were found accompanied by fibres newly formed and as yet without 

 a medullary sheath. Six experiments were made, four on dogs, two on 

 rabbits. The length of time intervening between the operation and the 

 examination varied in experiments on the dogs from thirty-five to eighty 

 days, on the rabbits from sixty-seven days to four months. The distance 

 at which the nerve ends were sutured varied from 3 to i >^ ctm. 



A review of these experiments shows a favorable termination 

 in each case ; in all, nerve fibres were found in the band 

 uniting the central and peripheral nerve ; conductivity of 

 nerve impulses had been established, as was shown by contrac- 

 tion of the muscle when stimulating the sciatic above the seat 

 of injury, and this after the nerve had been cut some distance 

 above the place of resection. 



