CHAP. YIII. MUSCULAR AND NEEVOUS TISSUES. 85 



as a wire may be supposed to be when traversed by 

 an electric current ; the fibre would appear rather 

 to represent an excited glass rod, as far as its mode 

 of action may be considered, rendering other parts 

 electric by induction ; but whether the force exists 

 of that intensity to produce attraction or repulsion, 

 would appear doubtful after the experiments of 

 Vassali Eandi'. It does not necessarily follow 

 that, because the current is produced, attraction and 

 repulsion should also be obtained ; the intensity 

 requisite in the one case may be absent in the other ; 

 and I cannot do better than refer to the important 

 Paper, by Faeadat, on the Gymnotus ', for the pur- 

 pose of pointing out the great difference manifested 

 in the two instances in regard to animal electricity 

 and machine electricity. But the conditions under 



' The following experiments of my own may, perhaps, be of 

 some interest. The limbs of frogs were suspended by means 

 of a silk thread to a glass beam, which was also suspended 

 horizontally by a silk thread attached to its centre, and fastened 

 above to another glass rod. Upon holding a silk thread near to 

 the limb, no attraction or repulsion of the thread was observed. 

 Exciting a glass rod, and presenting it to the limb, the limb 

 was powerfully attracted ; it was attracted also upon presenting 

 an excited stick of sealing-wax to it. But I never obtained any 

 eflFect, when one limb was presented to the other, either of 

 repulsion or attraction; it would appear as if one of the sub- 

 stances must be in an excited state to produce these phenomena. 

 I do not consider these experiments of much value, and not at 

 all adapted to eliminate any very correct result; but they tend 

 to indicate the negative character of the tissue. 



' Experimental Besearches, vol. ii. p. 1. 



