CHAP. IX. MDSO0tAR AND NEEVOUS TISSUES. 105 



changes in the condition of the nerve, the tetanized 

 state of the muscle might be a necessary consequence 

 until the nerve had acquired its normal and per- 

 manent condition. But the same remarks might be 

 made of the nerve in which the direct current has 

 passed, and yet no contraction occurs. This is a 

 diflSculty which at present we cannot satisfactorily 

 overcome; but the fact is of some importance, as 

 indicating a dependence upon the direction of the 

 electric current in its passage along the nerve, and 

 shewing that a peculiar state is induced in one case 

 and not in the other'. My endeavours to ascertain 

 what this state may be by means of the galvanometer 

 have hitherto failed. 



In all these discussions, the importance of con- 

 sidering the conditions both of the nerve tissue and 

 muscular tissue, in regard to their nutrition^, cannot 



' Matteuoci believes that the excitability of the nerve is 

 increased by the inverse current, and diminished by the direct 

 current. Phil. Trans. 1846, part iv. p. 483. It is possible that 

 the inverse current may keep up the normal electric condition of 

 the nerve, inasmuch as the current is similar in direction to the 

 natural current, and the direct current may destroy this normal 

 state, being in opposition to it. Under these circumstances, the 

 nerve current, if not increased by the inverse current, should 

 indicate some evidence of its continuing longer, and the opposite 

 effect should he produced by the direct current. At present my 

 experiments have failed to shew this. 



' I cannot do better than refer to the article on the " Phy- 

 siology of the Nervous System" in the Cyclopaedia of Anatomy 

 and Physiology, by Dr. Todd, in which this fact is clearly 

 pointed out. 



