PEOFESSOR MATTEUCCI’S ELECTRO-PHYSIOLOGICAL RESEARCHES. 
1.85 
Before quitting this subject, I gladly avail myself of this opportunity of mentioning an 
important fact discovered by M. Du Bois Keymond. From the period of my earliest re- 
searches in electro-physiology, I had vainly endeavoured to obtain electrical phenomena 
from the nerves of a IBing animal, or of one recently killed; and even now it is demonstrated, 
that, notwithstanding the use of the most delicate modern galvanometers, no sign of elec- 
trical current is to be obtained from a nerve laid bare in a living animal and left in its 
natural state. M. Du Bois Eeymond has, nevertheless, demonstrated, and the fact is 
easily verified with a very delicate galvanometer, that a piece of nerve detached from a 
li\ing animal prepared and disposed in the same way as a half-thigh, in the circuit of the 
galvanometer, produces constantly an electric current, which, like that of the muscle, is 
dii’ected from the surface of the nerve to the interior in the galvanometer. I have proved, 
by experiments made on pieces cut from the lumbar nerves of a frog, that the intensity 
of the cm’rent of the nerves mcreases with the number of elements united to form a pile, 
and that a pile of five or sis of these elements acts on the nerve of a galvanoscopic frog 
and excites contractions. I have compared the electromotive power of a muscle with 
that of a nerve, both belonging to the same frog. It is hardly necessary to say that this 
was done by opposing to a half-thigh as many nervous elements as were required in order 
to there being no differential current. In two experiments I found that one half-thigh 
predominated over seven nervous elements, and that nine of the latter predominated over 
one half-thigh ; in a th ir d experiment eleven or twelve nervous elements were required 
to predominate over the muscle. I left these piles under a glass bell, the air of which 
was saturated with moisture ; I could not perceive any marked difference in the relative 
duration of the electromotive power of muscles and nerves. 
§ 3. Let us now pass on to the development of electricity in the act of contraction. 
The first fact of this kind, which, for the sake of brevity, I shall continue to call induced 
contraction, was discovered by myself in 1842. I shall give here a very concise summary 
of the chief characteristics of induced contraction, although already known, having recently 
been led to repeat my former experiments, and to determine these characteristics with 
greater precision. 
In order to succeed in these experiments, it is necessary to operate on frogs in a 
vigorous condition, and prepared very rapidly. The fundamental experiment is made 
by laying the nerv'e of a galvanoscopic frog upon any muscle of a living animal. In order 
to simplify the experiment, I employ a single thigh of a frog, to which remain united the 
lumbar neiwe and a portion of the spine. On provoking contractions in the thigh, either 
with an intermittent current sent through the nerve, or by stimulating it in any other 
way, simultaneous contractions take place in the galvanoscopic frog. The disposition of 
the nerve stretched over the thigh is immaterial, as is also to a certain degree the length of 
the nerve put in contact with the muscle, as long as the muscle and the galvanoscopic frog 
are vigorous. I have frequently seen the strongest efiects of induced contraction when the 
nerve of the galvanoscopic frog, isolated from the operator, was in contact with any portion 
of the surface of the thigh for 2 or 3 millimetres only ; it is therefore by no means essen- 
