32 PRINCIPLES OP VETERINARY SURGERY 



lish the innervation of the part by the outward growth of its 

 axis-cyhnders, providing, however, the growth is not hin- 

 dered by loss of substance or obstructed by cicatricial tissue. 

 That is to say, if a nerve trunk is divided and the ends are 

 immediately brought into perfect apposition, the axis-cylin- 

 ders will rather rapidly grow down the old channel. It is 

 even claimed that the new axis-cylinders appropriate some 

 of the elements of the old ones as they advance toward the 

 periphery. Functional restoration under these most favor- 

 able conditions may occur after several weeks or several 

 months, but the function is not perfect even after several 

 years. The sensation is often blunted for life and the mus- 

 cular activity, if not assisted by compensatory augmentation 

 of other muscles, will remain rather imperfect for a long time, 

 if not forever. 



When a part of a nerve trunk, e. g". one-half to one inch, 

 is removed,perfect anatomical union and physiological res- 

 toration do not usually occur. The descending axis-cylinders 

 are blocked by the scar or are lost while wandering into the 

 surrounding tissues; a few of them may find the old channel 

 but they will establish only a very imperfect innervation 

 of the unnerved area. It has been shown by experiments 

 that if the lost piece is replaced by a similar piece, even 

 though taken from another animal, it will serve as a guiding 

 channel for the growing axones, and thus direct them into 

 the old trunk. Pieces of tubing, bone, rubber, etc., have 

 been used for the same purpose but with less favorable re- 

 sults. Thus Cluck implanted a short piece of the sciatic nerve 

 of a dog into a corresponding breach of the same nerve in a 

 rabbit and found that the unnerved part responded to chem- 

 ical and mechanical stimulants after eleven days. Unfortu- 

 nately the degree of the re-established sensibility and motion 

 is not mentioned. Tillman succeeded in restoring the func- 

 tion of a grafted nerve. In all of the experimental observa- 



