1870.] 



Nervous System. 



341 



duction of vocal sounds, while other fibres from the pure vagus govern 

 certain nutritive or organic functions connected with respiration. 



In order to separate the functions of the one from the other, we require 

 to destroy all the fibres of the accessorius and leave the others intact, which 

 has been done most effectually by Dr. Waller's process ; first disconnecting 

 the accessorius from the medulla, on Bernard's plan, and afterwards allowing 

 the animal to live sufficiently long for the fatty degeneration to take place, 

 or about seven or eight days. The vagus then being galvanized at every 

 part of its length, it is found impossible to affect either the action of the 

 heart or the stomach, and the only result is to cause slight movements of 

 the larynx. 



It is therefore evident that Sir Charles Bell's ideas respecting this nerve 

 are in a great measure demonstrated by this experiment ; the only excep- 

 tion being with regard to certain fibres of a motor nature distributed to the 

 larynx, which it may be surmised are derived from some anastomotic source, 

 and therefore not contained in the vagus at its origin. Dr. Waller referred 

 to the recent researches on this subject by Professor Vulpian, MM. Jolliet, 

 Schiff, and Heidenhain, who have confirmed the results above stated. 



The Lecturer then proceeded to his observations on the pneumogastric 

 and sympathetic nerves on man in health and in certain affections of the 

 nervous system. 



He was first induced to undertake this subject on account of the unsa- 

 tisfactory results obtained by galvanizing this nerve and the cervical sym- 

 pathetic on man. In man this operation is frequently resorted to by me- 

 dical men, but in no case has any one asserted that any of the known 

 symptoms of irritation of those nerves, such as stoppage of the heart's 

 action, dilatation of the pupil or contraction of the vessels, have been pro- 

 duced. The inference is that it is erroneous to suppose that they were in 

 any degree affected by galvanism. By means of mechanical irritation ap- 

 plied over these nerves in the neck, Dr. Waller, in 1862, found that most of 

 the known effects of their irritation, such as dilatation of the pupil &c, can 

 be induced. The principal effects thus induced are nausea, tenderness, or 

 oppression over the prsecordia, and stoppage of the heart's action more 

 or less complete ; dilatation of the pupil of the same side, and fall of tem- 

 perature of the cheek and ear, amounting to 2° or 3° Centigrade, as ascer- 

 tained by one of Geissler's delicate thermometers. All these effects corre- 

 spond to those produced by galvanism on the denuded nerves. By means 

 of the mechanical irritation of the pneumogastric in cases of vomiting, the 

 vomiting has been instantly stopped, sometimes returning again imme- 

 diately the irritation was removed ; at other times a permanent relief was 

 procured. 



He lastly referred to the effects of collapse and syncope produced by the 

 irritation of these nerves. This effect was well known to Aristotle, who 

 attributes it to the compression of the veins, and describes the effects very 

 accurately in the following passage : — 



2 d 2 



