100 Mr. Mayo on Human Physiology. 



Upon making a longitudinal section of the thickened sub- 

 stance, the cut ends of the tendon contained within it are 

 found to be about an inch apart, but connected together by 

 means of coagulated blood, and swollen cellular texture. 



'' If the tendo achillis be examined seven days after divi- 

 sion, the ends of the divided tendon are found united by an 

 intervening substance of greater thickness than the tendon 

 itself, that is readily separable from the skin and subjacent 

 parts. Upon a longitudinal section being made, the inter- 

 vening substance appears of a dark red colour, firm, and to 

 a certain degree elastic : it coheres in some parts firmly, in 

 others slightly, with the cut ends of the tendon, but strongly 

 and inseparably with the cellular sheath of the tendon, which 

 is discoloured for some distance : so that either end of the 

 tendon admits, without much force, of being displaced from 

 a socket in the intervening substance. 



*' At seventeen days after division, the intervening sub- 

 stance is found diminished in thickness, firmer, paler, and 

 inseparably coherent with the cut ends of the tendon, the 

 nature of which it gradually assumes. 



*' When a nerve is divided, the process by which the ends 

 are joined exactly resembles the mode in v/hich tendons unite. 

 Without detailing the appearances on dissection at an earlier 

 period, let me describe the state of the part at the time, 

 when the return of its function first manifests itself. 



^' The infraorbital nerve was divided on one end upon the 

 cheek of a cat, and a portion about a line in length was re- 

 moved from it. The skin of the upper lip immediately lost 

 sensation. The wound, however, readily cicatrized ; and by 

 the twentieth day sensation appeared entirely restored. 

 Upon examining the part at this period, the nervous fibrils 

 appeared to be united by a thick layer of tough grey semi- 

 transparent substance. On making a longitudinal section of 

 this substance, and of the nervous fibrils which entered it, 

 the extremities of the divided filaments appeared nearly two 

 lines asunder, and firmly coherent with the intervening sub- 

 stance : liere and there a whitish fibril seemed to extend fur- 

 ther into the connecting medium, but no restoration of con- 

 tinuity between the nervous fibrils was observable. 



" When the portio dura is divided on the cheek, it unites 

 in a similar manner ; but the nerve does not begin under 

 four weeks to resume the office of transmitting the influence 

 of the will. About this time, however, the eye-lids, which 

 hitherto have been motionless, are observed to be slowly and 

 imperfectly drawn towards each other whenever the surface 

 of the conjunctiva is touched." 



