SiGERSON — On the 8tudt/ of Nerve-Action. 269 



lesion, taste \vas not abolished, nor noticeably diminished in the corre- 

 sponding region of the tongue, as would have necessarily happened if 

 the facialis had furnished taste-filaments. 



Bellingeri was, it would seem, the first to attribute an active role, 

 in the function of taste, to the chorda tympani. His opinion has been 

 confirmed by the experiments of Moos, who has pointed out that, in 

 cases in which compression of the chorda tympani was caused by 

 certain operations in the ear, transient loss of taste supervened. In 

 the case of a patient from whom one half of the inferior maxilla had 

 been removed, together with the chorda tympani and the facialis at 

 its exit from the stylo-mastoid foramen, the gustatory nerve being 

 preserved, the sense of touch persisted on the corresponding anterior 

 region of the tongue, but the sense of taste had disappeared. This 

 experiment, however, did not differentiate the function of the chorda 

 tympani from that of the facialis. When the chorda tympani is 

 divided, in animals, it is found that the sense of taste is obscured, 

 whilst the sense of touch remains. 



The abstraction of a factor, though it may suffice to solve some 

 problems, is not capable of supplying satisfactory answers to the com- 

 plex questions which we have to deal with in this instance. In order 

 to understand the properties of the nerve in question with some 

 degree of completeness, it is not enough to observe what takes place 

 when its action is annulled, by whatever cause ; we must also endea- 

 vour to distinguish what phenomena happen when the nerve is 

 stimulated to action. Now, this experiment may be performed on 

 animals ; but as animals cannot intelligibly express the gradations of 

 perception obtained through a special sense-organ, tlie result must of 

 necessity be unsatisfactory — more especially as it yet remains to be 

 shown that their perceptions of sapid impressions are in perfect unison 

 with those of man. Hence, with respect to the case in point, it is 

 requisite to experiment on man. 



The agent of excitation which I found most useful was volta- 

 faradaic electricity, following, in this respect, the example of my late 

 distinguished master. Dr. Duchenne (de Boulogne). Having, there- 

 fore, employed faradisation in such a manner as to stimulate the 

 chorda tympani, on at least two hundred occasions, I may, I trust, 

 consider that the opportunities of observation have been sufficiently 

 frequent to reduce the risk of error to a minimum. One of the rheo- 

 phores was placed, immersed in water, in the external meatus ; the 

 other was usually appKed in the immediate vicinity. The time occu- 

 pied by each experiment varied from five to twenty minutes ; the 

 action of both currents was tested separately ; the number of inter- 

 ruptions was varied, and different degrees of intensity, from the 

 feeblest to the strongest that could be borne, were employed. 



Finally, in order to clear up some points, and to determine more 

 accurately, if possible, the several phenomena produced, I considered 

 it necessary to personally undergo the experimentation. 



The results of these various experiments may be summarised as 



