No. XVIL] APPENDIX. 267 



tried under the most trying circumstances, as I observe that the positive 

 pole, in the sulphate of copper, is almost entirely dissolved. Notwith- 

 standing, however, this, the law which I have developed and described in 

 my ' Electro-Metallurgy/ still holds good, though I must confess that I 

 should not have risked the demonstration of this extreme application of 

 the law, which fortunately, by accident, has brought the matter more 

 strikingly under your notice. 



From this law, we learn that the voltaic circuit would be completed 

 through the nearest motor nerve, when any sensation was excited, unless 

 obstacles were presented to its passage in that direction, or any circum- 

 stances favourable to its passage through any other motor nerve were 

 afforded in some more distant part of the Electro-Biological circuit, when 

 even the furthest motor nerve might be excited to action. 



The action of every animal is determined, then, not only by the 

 impression received at the moment, but by every other event which it has 

 registered or remembered from the first moment of its life. 



The motor nerves, by which the circuit is completed in the body, are 

 distributed, in man, to the muscles; in other creatures to the electric 

 organs ; in others, to light- generating structures. The electric battery of 

 fishes, as it is technically called, is composed of an enormous number 

 of minute cells, supplied with blood-vessels. The nervous force, which I 

 have already shown to be voltaic, acts at right angles to the direction of 

 the cells, and there produces some change of matter which instantly 

 causes a powerful voltaic current. 



I have here a glass vessel, containing a solution of ferrocyanate of 

 potash, into the interior of which is placed a porous cell, containing a 

 similar solution; a platinum pole is inserted into both vessels, for the 

 purpose of connection with the galvanometer. Now, if I pass a voltaic 

 current from the outside to the inside (z s), no change of matter takes 

 place in one part, the prussiate of potash remains the same; in the 

 other it is converted into the red prussiate. From this change one side 

 becomes strongly positive to the other, and you perceive that so powerful 

 a current has been generated, that the needle completely swings round 

 the instant connection is made with the galvanometer. I have only 

 shown this experiment upon one cell; but it must be manifest to you, 

 that as every cell adds a certain amount of force, it simply requires a 

 number to make a battery as powerful as that of an electric eel. The 

 artificial electric eel I have myself constructed, in a vast variety of 

 ways, which I have not now time to consider. 



The muscular substance is ultimately divisible into primitive fibrils, 

 which consist of a sheath, called the sarcolemma, containing, in the 

 interior, a peculiar matter, which, during the act of contraction, becomes 

 wider and shorter ; and this contraction is caused by a change of matter, 

 produced by the voltaic force, carried through the motor nerves. 



I have here a strong piece of gut to imitate the sarcolemma, and into 

 the interior of this I have placed fluid and pieces of platinized silver. 

 Upon the outer side of this gut is placed a strong piece of amalgamated 

 zinc, so that the moment connection is made between the zinc and silver, 

 gas is evolved, which renders the bladder wider and shorter, and thus 

 moves this bar of wood over a space of three or four feet. 



The conditions of the natural muscle and artificial muscle are per- 



