Dr. Waller on the Vagus and Spinal Accessory Nerves, 473 



between its upper and lower ganglia, the section comprising the 

 internal branch of the spinal accessory. After the animal had been 

 kept alive for a sufficient period to cause disorganization of the nerve 

 fibres, the central and distal portions were examined microsco- 

 pically. In the central portion, the fibres of the internal branch of 

 the spinal accessory included in the section were all in a sound 

 state ; some of the fascicles of origin of the vagus were also sound ; 

 the remaining fascicles of origin of the vagus consisted of dis- 

 organized fibres. The analogy existing between the results as to the 

 last-mentioned fibres, and those which follow section of the sen- 

 sory roots of the spinal nerves, led the author to the conclusion, 

 that the disorganized fibres of the fascicles of the vagus were like- 

 wise sensory, and had their trophic centre in its lower ganglion, 

 while the sound fibres probably had their trophic centre in the upper 

 ganglion. On these grounds, and some others affording concurrent 

 testimony, he concluded that the vagus in itself was probably a 

 purely sensory nerve. In the distal end, the part below the second 

 ganglion consisted likewise of a mixture of sound and altered fibres. 

 When tested by galvanism on the living animal, it was found that 

 the nerve had lost all power of exciting movement in the various 

 organs which it supplies, and that such branches of known motor 

 power as the recurrent and the crico-thyroid were disorganized in 

 their structure. It was evident therefore that the lower ganglion 

 did not arrest the disorganization of the motor fibres contained in 

 the vagus, because, as has been proved by the author in other cases, 

 when the disorganization of the motor fibres of nerves distributed to 

 muscles is arrested, — as by the superior cervical ganglion of the 

 sympathetic nerve, or by the effect of hybernation in the frog, — 

 the motor power of these nerves is retained. 



In the present observations, the accessory nerve was divided at 

 its origin by Bernard's process of evulsion of its roots, and after the 

 lapse of about a fortnight the vagus was tested by galvanism, and 

 examined by the microscope, in order to ascertain the functions 

 which it had lost, and the fibres which were disorganized, the 

 sound vagus on the opposite side being taken as a standard of com- 

 parison. On the sound side, galvanism of the vagus caused each time 

 strong dilatation of the glottis by the retraction of the corresponding 

 arytenoid cartilage. On the operated side, galvanism produced a 

 slight movement of the glottis on the same side by drawing inwards 

 of the arytenoid. 



On the heart, the action of galvanism of the sound vagus was 

 manifest by the stoppage of the pulsation of the carotid arteries 

 and the diminution of their calibre. On the operated side, no in- 

 fluence on the pulsation of the vessels was observed by galvanizing 

 the vagus. When the heart was exposed by removing a portion of 

 the thorax, and keeping up artificial respiration, galvanism on the 

 sound vagus produced complete stoppage of the heart's action, while 

 on the opposite side, irritation of the vagus exerted no influence on 

 the heart. 



Phil. Mag. S. 4. Vol. 1%. No. 81. Dec. 1856. 2 I 



