;wg 



Royal Society : — 



Let the following diagram and table represent the case in which a 

 loop of sciatic nerve is acted upon by the direct 'primitive current, 

 a being the nerve, P N the poles of the galvanic apparatus, the black 

 arrow the primitive current, the dotted arrows the derived current ; 

 and it will be seen that the portion of nerve between the negative 

 pole and the leg is acted upon by an inverse derived current, and 

 that the thigh is traversed by a direct derived current. Thus — 



Fig. 3. 



Hence there ought to be, as there is in fact, and as the Table 

 shows, contraction in the thigh when the current begins to pass, and 

 in the leg when the current ceases to pass. 



A similar diagram and table will give the case in which a loop of 

 sciatic nerve is acted upon by the inverse primitive current, and show 

 at a glance that the leg ought to contract at the beginning of the 

 current, because the current, acting upon the portion of nerve nearest 



Fig. 4. 



