THE VAGUS XERVE 425 



from the superior cervical ganglion, the sympathetic trunk or 

 inferior cervical ganghon. 



In other cases about an inch of combined vagus and sym- 

 pathetic trunk was removed in the midcervical region (fig. I, B). 

 Such a procedure would cut off any fibers to the vagus from the 

 superior cervical ganglion, but would in no way interfere with 

 fibers from the inferior ganglion. 



The dogs were autopsied after 2 to 8 weeks and jiortions of 

 the nerves studied after pre])aration by the pyridine silver 

 method fRanson '11. '12) and the osmic acid method. 



CHANGES AKTEIl .SIXJTIOX OF THE VACU'S ALONE HKUI IN 

 THE NEf'K 



Sections fi-oiii llie right \agus of a dog autoi)sietl five weeks 

 after removal of a ])oition of \]\o upper cervical vagus, the .sym- 

 pathetic l)eing left intact, show definite degenerative changes. 

 A cross section stained l)y the pyridine silver method, taken 



Via. 1 Diagram of tlic ri<ili( vami.s iiorvo in the (I<ir 



J'in. L' From a .soction of riKlit vajius norvc at level indicated (fig. 1, f, 5), 

 following removal of a jiortion of the vao;us and sympathetic trunks at level B, 

 figure 1. Pyridine silver. X 1140. 



Fig. 3 From a section of the same nerve at same level as figure 2. Osmic 

 acid. X 1140. 



Fig. 4a From a section of a normal vagus nerve just l>elo\v pulmonary ]ilex- 

 uses (fig. 1, 4«)- Pyridine silver. X 1140. 



Fig. 4b From a section of the same nerve as figure 2. helow the pulmonary 

 plexuses (fig. 1, 4b)- Pyridine silver. X 1140. 



a, vagus rootlets n.r.i.. iiervus caroticus internus 

 A,B., indicate levels at whicli portions n.l.s., nervus laryngeus superior 



of the vagus trunk were removed n.r., nervus recurrens 



art.s., arteria suhclavia n.r., nervus vagus 



a.s., ansa subclavia ^^.r.^.s., nervus vagus and truncus sym- 



b, bulbar rootlets of the accessory nerve pathicus 



c, spinal root of the accessory nerve p.o., plexus csophageus 

 g.c.i., ganglion cervicale inferior r.b., rami bronchiales 



g.c.s., ganglion cervicale superius r.e., ramus externus n. accessorii 



g^.j., ganglion jugulare r./j., ramus pharyngeus 



g.n., ganglion nodosum t.s., trunkus sympathicus 



g..s., ganglion steliatum 2, 3, 4a, 4b, indicate levels at which the 



I.V., left vagus corresponding figures were taken 



