Electricity and Galvanism. 133 



as well as cold-blooded animals. Indeed more intensely, but very 

 soon disappearing on the death of the animal. These researches 

 completely corroborate the statements and experiments of Aldini 

 made many years earlier, especially that very remarkable one before 

 alluded to, in which he produced contractions of the legs of a frog 

 by bringing them in contact with the tongue of an ox. 



By means of the frog galvanoscope, not only the existence, but 

 the direction of a current can be discovered ; for if the leg be kept 

 for a short time before using it, so as to a little diminish its sensibi- 

 lity, the muscles will contract on making contact with the body 

 under examination, if the electricity passes from the nerve to the 

 leg, whilst it will contract on breaking contact if the electricity is 

 moving in the opposite direction. Using this delicate test for an 

 electric current, Matteucci discovered that the intensity of such cur- 

 rents rises in proportion to the rank occupied by the animal in the 

 scale of being, their duration after death being in the inverse ratio. 

 The Professor discovered that when a mass of muscle belonging to a 

 living animal, or one recently dead, was placed in contact with a 

 piece of wire so that one end of it touched the tendon, and the other 

 the body of the muscle, a current could always be detected circulat- 

 ing in the mass in the direction from the tendon to the external 

 surface of the structure. He further demonstrated the very impor- 

 tant fact, that everything which decreases the vis vitce of the animal 

 diminishes the evidence of electricity immediately after death. Thus, 

 when frogs were killed by asphyxia, either by immersion in sulphu- 

 retted hydrogen, or water freed from air, the electricity detected in 

 their femoral muscles sunk to a minimum ; whilst the thighs of frogs, 

 whose hearts had been previously removed, gave less evidence of the 

 existence of this important agent than those which had not been 

 thus injured. 



It is well known that certain fishes possess a peculiar apparatus by 

 which they are enabled to accumulate the electricity developed by 

 the vital processes going on in their structures, and thus produce 

 the ordinarily recognised effects of tension, as shewn in the benumb- 

 ing shock felt on grasping a torpedo or silurius. This endowment 

 is, however, peculiar to very few creatures, and all the electricity 

 developed in the frames of other organisms is only to be detected by 



