132 
PEOFESSOE MATTEIJCCI’S ELECTEO-PHTSIOLOGICAL EESEAECHES. 
fully amalgamated plates of zinc for those of platinum, and the use of a saturated solu- 
tion of chloride of lime or sulphate of zinc, as liquid. The merit, however, of this great 
improvement in the apparatus for electro-physiological researches is due to M. J. Eeg- 
NAULD, as this young physicist was the first who published it, he ha%ing employed plates 
of distilled zinc instead of platinum. Now that the existence of muscular electricity, 
and that of its principal laws, is proved beyond all doubt, we may freely employ this 
method, the advantages of which will shortly be seen, without feaiing, as formerly we 
justly did, errors which might be introduced into the experiment by the use of zinc elec- 
trodes and highly conducting liquids. I need only cite the following instance to show 
the great difference which results from this mode of making the experiment. AYith 
plates of platinum and diluted solution of common salt which I am in the habit of 
employing, either a gastrocnemius or a half-thigh of a frog of ordinary wgoiu’ produces, 
with a galvanometer of 24,000 coils, a deflection of 30° or 40°, which in a few seconds 
decreases to 2°, then 1°, and soon ceases almost entu’ely. "With plates of amalgamated 
zinc immersed in sulphate of zinc, all heterogeneity between the plates ha^Tng ceased, a 
gastrocnemius or half-thigh gives at the first impulse a deflection of the entire quadrant, 
the needle then rests at 70° or 80°, and descends extremely slowly; when the muscle is 
taken away and the needle fixes at 0°, no sign of polarization is obtained by biinging the 
two conducting cushions into contact. 
I shall now state the results of my recent researches on the muscular cmTent in 
some general propositions : the experiments of which I shall have occasion to speak have 
been so often verified that they may be easily repeated without uncertainty. 
Prop. I. The electromotive ])Oiver of a cut muscle is independent of the size of its trans- 
verse section. 
Several half-thighs of frogs of equal vivacity are prepared of the same length, taking 
care to leave no portion of muscle beyond the articulation of the leg. These half-thighs 
are ranged opposite to each other in parts, in order to ascertain the equalirt of thert- 
electromotive power ; any elements which are unequal are rejected. Five or six of these 
half-thighs, laid closely one upon the other in the same direction, are then piled upon 
the usual gutta-percha holder ; a single half-thigh is opposed to this heap. The circuit 
is closed, and the differential current is either null or very small, sometimes in the drt’ec- 
tion of the single thigh, sometimes in that of the heap. I repeated this experiment wth 
two elements only, i. e. with two half-thighs taken from frogs of different size and 
weight ; the difference of weight between these elements was as between 1 and 5 or 1 
and 6, It is easy to perceive that this method is less exact than the former, since the huger 
frogs are more robust in the same conditions. The differential current was always ex- 
tremely weak, but in the greater number of cases the drt’ection was determined by the 
largest, and consequently most robust element. 
Prop. II. The electromotive force of the muscle increases ivith its length. 
This proposition may also be established by the differential method. Take two half- 
thighs of equal length, and which have the same electromotive power. Eeduce by a 
