a7id Remarks on the Contractions of the Frog. 197 



prepared after the method of Galvani the observations which 

 we had made respecting this point, as well as others also re- 

 lating to the torpedo, for which we are indebted to various 

 philosophers; at the same time he has demonstrated some 

 new facts, of which the following is a short account. 



He commences by showing that when the torpedo lances 

 its discharge no change of volume is observed in its body. 

 When the animal is possessed of great liveliness the sensation 

 is felt at whatever point of the body it may be touched, but 

 when its vitality is considerably diminished the discharge is 

 no longer felt, except by touching the electrical organs at two 

 different points. 



Matteucci establishes the general laws of the distribution of 

 electricity in this manner: — 1. All the points of the dorsal 

 part of the organ are positive relatively to the points of the 

 ventral part; a fact already known. 2. The points of the 

 organ on the dorsal surface placed above the nerves which 

 enter it are positive in respect to the other points of the same 

 dorsal surface. 3. The points of the organ situated on the 

 ventral surface corresponding to the points which are positive 

 on the dorsal surface are negative in respect to the other points 

 of the ventral surface. 4. The intensity of the current varies 

 with the extent of the platina plates which terminate the 

 galvanometer, and with which the two surfaces of the organ 

 are touched. 



When the torpedo is very excitable the current may be 

 compared to that of a pile consisting of a great number of 

 pairs charged with a good conducting active liquid ; whilst, 

 on the other hand, when its liveliness is weak, the electric 

 current resembles that of a pile composed of a small number 

 of elements. 



The spark which accompanies the discharge in the electri- 

 cal fishes was remarked for the first time by Walsch in the 

 Gymnotus; many vain efforts have been made since to repro- 

 duce it; MM. Matteucci and Linari have succeeded in ob- 

 taining it in every case from the torpedo ; both these philoso- 

 phers claim the priority of the observation. It appears from 

 the notices which we have gathered that Matteucci was the 

 first who had the idea of employing for this purpose Faraday's 

 apparatus of the extra current, which M. Linari did not 

 make use of until after it had been pointed out to him by his 

 countryman. 



Matteucci has since succeeded in obtaining the spark by 

 placing the torpedo upon an isolated plate of metal, and pla- 

 cing another plate of metal above it, then fixing to each of them 

 a gold leaf separated the one from the other by the distance 



