VOL. LXXXIII.] PHILOSOPHICAL TRANSACTIONS. 287 



the frog in preference to every other animal, because it is endued with a very dura- 

 ble vitality, and is also very easy to prepare. Mr. V. also made trial of other 

 small animals for the same purpose, and with nearly the same success. Hence 

 he found, that for the living and entire frog the electricity of a simple middle- 

 sized conductor was sufficient, when it was only capable of giving a very feeble 

 spark, and to raise Henly's electrometer to 5 or 6°. When he used a Leyden 

 phial of a middle size, a much weaker charge produced the effect, viz. such as 

 gave not the least spark, and was quite insensible to the quadrant electrometer, 

 and hardly sensible to Cavallo's electrometer. 



All this was for a whole and isolated frog : but for one dissected and pre- 

 pared in different ways, especially after Galvani's manner, where the legs are 

 attached to the dorsal spine only by the crural nerves, a still much weaker elec- 

 tricity, whether of the conductor, or of the Leyden phial, the fluid being 

 obliged to pass through the narrow passage of the nerves, never failed to excite 

 convulsions, &c. Hence then we have, in the legs of the frog attached to the 

 dorsal spine only by the bare nerves, a new kind of electrometer ; since the 

 electric charge which, giving no signs by other the most delicate electrometers, 

 gives evident tokens of it by this new means, by what may be called the animal 

 electrometer. 



But if after these experiments, we ought not to be surprized at those of Gal- 

 vani described in the 1st and 2d parts of his work, how can we avoid being so at 

 the very novel and marvellous ones in the 3d part ? by which he obtains the same 

 convulsions and violent motions of the members, without having recourse to 

 any artificial electricity, by the sole application of some conducting arc, of which 

 one extremity touches the muscles, and the other the nerves or the spine of the 

 frog, prepared in the manner aforesaid. This conducting arc may be either 

 wholly metallic, or partly metallic, and partly some of the imperfect conductors, 

 as water, or one or more persons, &c. Even wood, walls, the floor, may enter 

 into the circuit, if they be not too dry. The bad conductors however do not 

 answer so well, and only for the first moments after the preparation of the frog, 

 as long as the vital forces are in full vigour ; after which the good conductors 

 only can be used with success, and soon after we can only succeed with the most 

 excellent ones, viz. with conducting arcs wholly metallic. Galvani successfully ex- 

 tended these experiments not only to many other cold-blooded aiiimals, but also to 

 quadrupeds and birds, in which he obtained the same results, by means of the same 

 preparations ; which consist in disengaging from its coverings one of the prin- 

 cipal nerves, where it is inserted into a member susceptible of motion, in arm- 

 ing this nerve with some metallic plate or leaf, and in establishing a communica- 

 tion, by help of a conducting arc, between this arming and the depending 

 muscles. Thus he happily evinced the existence of a true animal electricity in 



