57 



nerves from a ganglion, it has been 

 thought that ganglia, by intercepting the 

 direct communications between the brain 

 and the extreme branches of nerves, might 

 render parts thus supplied less amenable 

 to the will, and less under the influence 

 of the general affections of the nervous 

 system. It is also thought that gan- 

 glia might serve the office of subsi- 

 diary brains, each affording a separate 

 source of nervous energy. 



Ou the one hand, it ought to be ob- 

 served, that all the vertebral nerves, sup- 

 plying parts over which the will exerts 

 the most perfect control, have ganglia at 

 their commencement ; and that the nerves 

 of the leg and arm form a plexus ne.ar 

 their origin. The actions of the cremaster 

 muscle are involuntary; yet I believe it 

 is supplied by the same nerves, which 

 supply muscles that are subject to 



