188 Scithtific Intelligence, — Zoology. 



nerve is restored. On examining the swelling some time after- 

 wards, it is found to be of a bright or greyish-red colour exter- 

 nally, and white in the centre ; and medullary fibres are seen 

 passing through it, and completely connecting the nerves. The 

 knot remains for a long time after the cure has been completed. 

 It has been found 50, 60, 90, 100, 110, and even 185 days 

 after the division of the nerve. The author observed it in dogs 

 two years after; and in the human subject, six or eight years 

 after the amputation of the arm. — It is a question which has 

 given rise to much controversy, whether the substance connect- 

 ing the divided extremities of the nerves has the true nervous 

 texture, and be capable of conveying sensation to the brain, and 

 volition from it. Arnemann, Michaelis, Meyer, Cruickshank, 

 and Haighton, insist that the nervous substance is really regene- 

 rated, and that the nerve becomes capable of again performing 

 its functions. Prevost also made some experiments on cats, 

 which led to the same result ; and Swan came to the same con- 

 clusion from his experiments on rabbits and dogs. The prece- 

 ding experiments certainly go to prove, that a true regeneration 

 of the nervous issue takes place ; but none of them are very satis- 

 factory as to the restoration of the powers of sensation and motion 

 to the parts whose nerves had been divided. The author of this 

 paper consequently determined to make some more decisive ex- 

 periments on the subject; one of the most satisfactory of which was 

 the following. On the 16th August 1827, he laid bare the axillary 

 plexus of a dog, parted the several nerves, and cut out of each a 

 piece of from 10 to 12 lines in length. The animal immediately 

 lost all power of feeling and motion in the corresponding limb. 

 The wound healed in three weeks, the limb continuing in the same 

 paralyzed state, and appearing evidently wasted, in comparison 

 with the other fore leg. When the dog walked or ran, it went 

 on three legs, and raised the fourth by means of the muscles of 

 the shoulder. In May 1828, that is, eight months after, the 

 author observed that the animal began to use the injured limb 

 again, and that when pinched or pricked -with a needle in the 

 paw, it showed some signs of feeling. During that and the fol- 

 lowing year, the powers of sensation and motion gradually re- 

 turned, till at last they seemed as perfect as they had been pre- 



