ANIMAL ELECTRICITY. LECTURE I. 9 



tion of activity at L, the resting part, than at T, the 

 already active part. The current of injury generated 

 at T was due to a cHfference between T and L, its 

 negative variation generated at L was due to a 

 diminution of that difference. And there must be 

 a difference before there can be a diminution of 

 difference; there must be a current of injury for you 

 to get a negative variation of it. If the muscle had 

 been chemically homogeneous throughout, whether at 

 rest or in action, with therefore any two points T L 

 equally zincable or equally zincative, there could have 

 been no (or little) difference aroused between T and 

 L when both are equally (or nearly equally) altered. 



Second Represent alive Experiment (on Nerve). — 

 In the first experiment (on muscle) the nerve was 

 used merely as an instrument to stir up the muscle, 

 and the muscle spoke in two ways — by an actual 

 movement of its substance, by a chemico-electrical 

 change revealed in the galvanometer. 



In this second experiment (on nerve) the nerve 

 is to be used by itself, cut off from its natural organ 

 of expression, which is muscle, and connected by the 

 points T and L with a galvanometer that will serve 

 as an artificial organ of expression. 



We shall begin by testing the nerve for current 

 of injury, expecting to find it directed in the nerve as 

 in the muscle from disturbed Transverse section to 

 undisturbed Lonoritudinal surface. And so it is. 



Now, let us arouse the whole nerve — and for the 



