He owes his success in a great measure to his galvanometer, which admirable instrument, made by himself, is so sensitive that the exceedingly weak current from two parts of the skin, even very near each other, is felt by it. The wire wound upon the frame of this apparatus is 5,584 yards or more than 3 miles long; it forms 24,100 coils around the frame. However, it is not necessary to employ such a powerful instrument to prove the existence of animal electricity, and the ordinary galvanometers may answer the purpose. Before the researches of Du Bois-Reymond it was admitted that there were two kinds of muscular currents, one belonging to divided muscles and the other to undivided muscles. The first had been very well observed by Matteucci, who ascertained that it is constantly directed from the interior of the muscles to its surface. It exists in the muscles of all the animals which have been examined, and Brown-Sequard has found it in man. As to the other current, that of undivided muscles, it is what Nobili called the proper current of the frog.

Du Bois Reymond found that this current exists also in the higher animals, and that its direction varies extremely according to many circumstances. In the limb of the frog this current is directed from the tendon of the prin-cipal muscles to their surface. If' in certain animals the current seems to be weak, although it may be in reality strong, it is because in some muscles the tendon is placed at one ex-tremity and in others at the other, and that sometimes there are two tendons. - The gal-vanic current of muscles gradually diminishes after the death of animals, or after the separa-tion of the muscles from the living body. Ac-cording to the researches of Du Bois-Revmond, and numerous experiments made by Brown-Sequard, the laws regulating the diminution i and the disposition of the muscular current are the same as those of muscular irritability. Between these two physiologists, however, there is this difference, that u Bois-Reymond thinks that the cessation of the current takes place at the time a supposed coagulation of i the fibrinous liquid of the muscles occurs, producing the so-called cadaveric rigidity; while Brown-Sequard has shown that there; is no such thing as this coagulation where cadaveric rigidity supervenes.

The latter I physiologist has discovered that the muscular current, after having completely disappeared (cadaveric rigidity being fully established), may be reproduced, together with the mus-cular irritability, when an injection of blood ! charged with oxygen is made into the arteries I of a limb. This experiment he has per-! formed not only on animals, but on the ! limbs of guillotined men. He found that the more oxygen there is in the blood employed, the quicker the muscular current and rita-: bility return. This fact, with many others dis-: covered by Matteucci and Du Bois-Revmond, shows that the production of the current depends on the nutrition of the muscles, and par-ticularly on the oxidation of their tissues. Prof. Matteucci published many facts to prove that the muscular current is independent of the nervous system; but his experiments are all open to objections. More decisive researches have been made by Brown-Sequard, who has ascertained that in muscles whose nerves have completely and definitively lost their vital prop-erties, currents not only exist during life, but I may be reproduced by the influence of injec-tions of oxygenated blood when they have dis-appeared after death. - Du Bois-Reymond has established as a law that every point in the natural or artificial longitudinal surface of a j muscle is positive in relation to every part of its transverse surface, whether natural or artificial; and as the tendons, which are conduc-tors, are in communication with the natural transverse surface, it follows that they are negative as regards this surface.

This law signifies that the longitudinal surface of a muscle ! acts like the positive pole of a pile or galvanic battery, while the transverse surface acts like the negative pole. According to this important law, when any point of the longitudinal section of a muscle is connected by a conductor with any point of the transverse section, an electric current is established, which is directed in the muscle from the transverse to the longitudinal section. Du Bois-Reymond has discovered that the smallest part of a muscle acts in the same way as the whole of it, except that the strength of the current is less and less powerful as the part is smaller. Each elementary bundle of fibrils in a muscle seems to be like a couple in a galvanic battery, except that the couples represented by these elementary bundles are not able to transmit their current so freely as the couples of a real galvanic battery usually are. Du Bois-Rey-mond has found that the amount of electricity generated in muscles must be excessively great; but as it is impossible to make an aggregation of all the elementary currents existing in a muscle, we have not a real measure of the quantity of electricity produced in these organs. - We owe to Matteucci the discovery of one of the most important facts concerning animal electricity.

He found that when a muscle contracts, if there is a nerve placed upon it leading to another muscle, the latter contracts also. The contraction of this second muscle Matteucci calls induced. To facilitate the understanding of what we have to say on this subject, we will call not only this second-arv contraction induced, but also the muscle that exhibits it, and we will call the first contraction and the muscle in which it takes place inducing. Matteucci had a great deal of trouble in trying to explain this induced or secondary contraction; his latest view was that it results from a galvanic discharge from the inducing muscle on the nerve of the induced one. Du Bois-Reymond, who has carefully examined the circumstances of this fact, explains it otherwise. He supposes that the current of the inducing muscle passes through the nerve of the induced one, and that when the inducing muscle is set in contraction, the current diminishes, and. as any diminution of a continuous current passing through a nerve is a cause of contraction for the muscle which it animates, it results that the induced muscle contracts.