The abstraction of a factor, though it may suffice to solve some
is not capable of supplying satisfactory answers to the com-
R estions which we have to deal with in this instance. In order
d the properties of the nerve in question with some
of completeness, it is not enough to observe what takes place
its action is annulled, by whatever cause; we must also endea-
to distinguish what phenomena happen when the nerve is
to action. Now, this experiment may be performed on
; but as animals cannot intelligibly express the gradations of
{Pmception obtained through a special sense-organ, the result must of
uty be unsatisfactory—more especially as it yet remains to be
that their perceptions of sapid impressions are in perfect unison
wth of man. Hence, with respect to the case in point, it is
‘Mguisite to experiment on man.
The agent of excitation which I found most useful was volta-
femadaic electricity, following, in this respect, the example of my late
@utinguished master, Dr. Duchenne (de Boulogne). Having, there-
fore, employed faradisation in such a manner as to stimulate the
¢horda tympani, on at least two hundred occasions, I may, I trust,
eeasider that the opportunities of observation have been sufficiently
to reduce the risk of error to a minimum. One of the rheo-
Phores was placed, immersed in water, in the external meatus; the
ther was usually applied in the immediate vicinity. The time occu-
Wed by each experiment varied from five to twenty minutes; the
ction of both currents was tested separately; the number of inter-
Tuptions was varied, and different degrees of intensity, from the
to the strongest that could be borne, were employed.
