BRACHIAL PLEXUS OF NERVES IN MAN 305 



to follow these through the funiculi. To do this would necessi- 

 tate the removal not only of the epineurium but also of the peri- 

 neurium. I do not believe that this is anatomically possible. 

 Some investigators have apparently been more successful in re- 

 moving the epineurium and tracing nerve bundles and nerve 

 fibers through the plexus. Their reported results indicate that 

 they were able to follow not only the funiculi but the fibers of a 

 given spinal nerve and that they could make out the distribution 

 of the fibers to the various branches of the plexus. 



SEPARATION OF NERVE BUNDLES BY MACERATION 



In order to see how far it was possible to remove the connective 

 tissue by chemicals and to trace back the nerves to their ele- 

 mental constituents, I have experimented with various macerating 

 fluids. That which I found the most satisfactory consisted of 

 20 parts of strong nitric acid and 20 parts glycerine in 40 parts 

 water. A number of plexuses have been macerated in this fluid. 

 A plexus placed in this macerating fluid was allowed to remain 

 until the connective tissue of the epineurium was soft and pulpy 

 and could be easily removed with a soft camel's hair brush. 

 The nerves were allowed to remain in the fluid 48 hours or more 

 depending on the method by which they had been embalmed 

 and hardened. When the epineurium was sufficiently softened 

 there was a decided shortening in the length of the plexus. 

 This occurred suddenly when the maceration had been carried 

 to a certain stage and not gradually as the maceration progressed. 

 The cause of this contraction I have not been able to explain. 

 When sufficiently macerated so that the epineurium could be 

 easily removed, plexuses may be kept for almost any length of 

 time in strong alum solutions or in 10 per cent formalin. As it 

 is the connective tissue that gives the strength to the nerves they 

 are. after maceration, easily broken and must be handled very 

 carefully. Even if the maceration is continued for a much longer 

 time, it does not soften the perineurium. This remains as a 

 smooth definite sheath around the nerve bundles until with pro- 

 longed maceration the whole plexus becomes so pulpified and so 

 softened that it cannot be studied at all. I do not know whether 



