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XYIII. Electro-Physiological Besearches. — Eleventh Series. On the Secondary Electro- 
motor Power of Nerves, and its Application to the Explanation of certain Electro. 
Physiological Phenomena. By Signor Caelo IVIatteucci. Communicated hy General 
Saeii^e, Treas. and V.P.B.S. 
Received June 2, — Read June 20, 1861. 
The object of this memoir is to describe experiments which prove that whenever a nerve 
is traversed by an electric current, it acquires in all its points a secondary electromotor 
power, and consequently becomes capable of producing in a conducting homogeneous cir- 
cuit, whose extremities touch any two points whatever of that nerve, an electric current 
in a contrary direction to that of the current which we shall call the exciting current. 
This property of nerves, which, as we shall see, is independent of their vital faculties, 
is nevertheless connected with their structure, and ceases when the integrity of that 
structure is impaired. All porous bodies, whether organic or inorganic, when saturated 
with a conducting liquid, are capable of acquiring a secondary electromotor power, so as 
to become a sort of secondary pile of Bitter ; but I do not enter into an examination 
of these phenomena, which have been studied in their generality by other physicists, 
my principal aim being to determine exactly the conditions of the secondary electro- 
motor power of nerv'es, in order to make a due application of these conditions to the ex- 
planation of the electro-physiological phenomena which are awakened at the opening 
of the voltaic circuit. 
I shall begin by giving such a minute description of the experimental arrangements 
which I have followed as may enable others to repeat my experiments vrith ease, and 
furnish, as I believe, an unfailing method for conducting electro-physiological researches 
in general. 
There is but one special instrument required in these researches, namely, a very 
delicate galvanometer, of from 24,000 to 30,000 coils of fine wire. 
Many years ago I introduced in electro-physiological experiments the use of amalga- 
mated zinc plates as extremities of the galvanometer, which may be employed much more 
easily and surely than the plates of distilled zinc proposed by Jules Reqnault. I used also 
two small glasses, inside of which were fixed two thick strips composed of a great many 
layers of unsized paper or of flannel, forming a sort of cushion bent horizontally over 
the rim of each glass, like the cushions employed by Du Bois Reymond : these glasses 
were filled with a saturated solution of sulphate of zinc, into which were plunged the 
plates of amalgamated zinc. Before beginning the experiment, the two glasses were 
brought near to each other, so that the cushions were put in contact. If the slightest 
MDCCCLXI. 3 E 
