382 INNERVATION. [CHAP. XI. 



ment of the phenomena, the signs of the electric current are just as distinct 

 when the circuit is completed by the contact of other parts ; or if the con- 

 tinuity be maintained by muscles, the main nervous trunks having been 

 removed. Thus, if a frog be flayed, and the bones and muscles of the pelvis 

 be cut away, so as to leave the lower extremities attached to the thorax by 

 the lumbar nerves, contractions will be produced by bending up the leg so as 

 to bring it in contact with the eyes, the muscles of the head, or the back. And 

 if this frog be placed with its head in one capsule and its legs in another, the 

 current may be detected by the galvanometer in the ordinary way. Or, if the 

 spinal nerves and the piece of the spinal cord be removed from the lower 

 limbs prepared in the ordinary way, the signs of the current may be obtained 

 in the usual methods. Piles made of legs prepared in this way develop a 

 current equally intense with that produced from piles with an equal number 

 of elements composed of limbs with the nerves remaining. It thus appears 

 that the electro-motor element of the current is reduced to the muscles of the 

 leg and thigh in organic union. 



So far, indeed, is the nerve from contributing to the production of the 

 electrical phenomena, that Matteucci found that a more feeble current was 

 developed in piles formed of the legs of frogs in which a very long portion of 

 the nerve formed an element. He prepared the legs, leaving attached to them 

 the lumbar and crural parts of the nerve, and formed the pile by placing the 

 nerve on the adjacent leg, so that the communication between the segments 

 was maintained only by the nerves. And it may be shewn further, that the 

 nerve in, these experiments, acts only as a bad conductor of the electricity 

 developed by the muscles ; for, if the nerves be cut away, and the segments 

 of the limbs connected by pieces of moist cotton instead, the phenomena of 

 the pile continue unchanged. 



Nothing analogous to the proper current has been found in any other rep- 

 tiles but the Batrachian nor in any other class of animals. It is not im- 

 probable, therefore, that the proper current of the frog may be due to some 

 undiscovered peculiarity of structure in that animal. 



How can we explain these remarkable electrical phenomena in the muscular 

 current directed from the interior to the exterior of all muscles in all animals ; 

 and the proper current of the frog, directed from the feet to the head, and 

 peculiar to the Batrachian reptiles ? 



It is not difficult to discover an explanation of the muscular current. The 

 essential conditions necessary to develop the signs of this current are simply, 

 that, by means of a conducting material, the interior of the muscular mass 

 should be brought into communication with the exterior of the muscle, which 

 is more or less tendinous, and covered with areolar tissue, and therefore 

 different from the interior in structure and function. And as the signs of this 

 current are apparent only whilst the muscle is living that is, while it con- 

 tinues to display its contractile power, we may infer that the same organic 

 conditions which are necessary to the development of contraction, are requisite 

 for the development of electricity. Now all that is necessary for the de- 

 velopment of the contractility of muscle is (as has been shewn in Chap, vii.) 

 a healthy nutrition, a due supply of arterial blood, and sufficient exercise of 

 the organ. And it would be impossible, as Matteucci remarks, not to admit 

 that the chemical action which must be going on throughout muscle, in the 

 constant supply and waste of which it is the seat, can be unattended with the 

 development of electricity. 



