NERVOUS POWER. 



255 



sympathies among the organs; but the wliole assemblage of 

 these nerves is more commonly known by the name of the 

 ganglionic system^ from tlie circumstance of their being 

 connected with small masses of nervous substance, termed 

 ganglia, which are placed in difTcrent parts of their course. 

 Fig. 379, represents a ganglion (g,) through which the 



nerve (n,) consisting at its origin of a number of separate 

 filaments (f,) is seen to pass, before it subdivides into 

 branches (b.) The numerous communications and inter- 

 changes of filaments, which subsequently take place at vari- 

 ous parts, forming what is called ^plexus, are shown in Fig. 

 380: where four trunks (t, t,) divide into branches, which 

 are again separated, and variously reunited in their course, 

 like a ravelled skein of thread, before they proceed to their 

 respective destinations. 



The ganglia are connected by nervous filaments with 

 every part of the brain and spinal marrow, the great central 

 organs of the nervous system; and they also send out innu- 

 merable branches, to be distributed all over the body. All 

 the parts receiving blood vessels, and more especially the 

 organs of digestion, are abundantly supplied with ganglionic 

 nerves; so that, by their intervention, all these parts have 

 extensive connexions with the brain and spinal marrow, and 

 also with one another. The ganglia are more particularly 

 the points of union between nervous fibres coming from 



