16 On the Excitability of Motor Nerves. [May 4^ 



current in the nerve was broken. Conversely, if the nerve was thrown 

 into kathelectrotonus, the pulsating e:ffect could be produced in the 

 muscle by a current of less intensity than was required to produce this 

 effect when the nerve was either in anelectrotonus or in the normal 

 state. 



§ 7. I have made several experiments with the view of showing the 

 major influence of the kathode on closing, and of the anode on opening, 

 in the case of well-curarized muscle ; but on the present occasion it 

 seems unnecessary to describe more than one. 



If the curarized sartorius of a frog is placed on non-polarizable elec- 

 trodes, and is somewhat stretched in a longitudinal direction by means 

 of two weights attached to its two ends, it may almost invariably be 

 observed (especially when the contractions become sluggish by exposure 

 of the muscle) that upon closure of the circuit, and during all the 

 time of its passage, the substance of the muscle draws towards the 

 kathode, while on the kathode itself the substance of the muscle heaps 

 up and spreads out in a very beautiful and distinctive manner. On now 

 reversing the current, all the phenomena take place in the reverse way. 

 Hence, by placing any minute body anywhere on the muscle between the 

 poles, this body may be seen to travel some distance towards the kathode 

 every time the current is reversed. Again, if a small transverse incision 

 be made in the muscle anywhere between the poles, it gapes towards the 

 kathode every time the current is reversed. Lastly, if two appropriately 

 weighted levers be attached one to each end of the muscle, when the 

 current is passing in one direction the lever nearest the kathode is 

 raised ; whereas when the current is reversed this lever, which is now 

 nearest the anode, falls, while the other lever rises. 



§ 8. If the copper wire terminals of a Daniell s element be taken one 

 in each hand, and the strength of the current be graduated down to the 

 point at which minimal stimulation is obtained by placing on a fresh 

 muscle first the anode and then the kathode, it may invariably be 

 observed that if this order is reversed, by first laying on the kathode and 

 then the anode, no contraction will be given unless the strength of the 

 current is somewhat increased. This curious fact may be observed 

 equally well on curarized and on uncurarized muscles. It is independent 

 of the direction of the current, and is not affected either by insulation of 

 the muscle or by placing it on a gas-pipe. The phenomenon is likewise 

 unaffected by placing the anode or the kathode in an unclosed circuit of 

 a Grrove's cell upon the muscle, and then experimented with the weakened 

 circuit from the Daniell's cell as before. It may be observed that the 

 long muscles of the thigh, either in situ or excised, are best adapted for 

 making these experiments *. 



* Until a short time ago I was not aware that any difference had as yet been detected 

 between the effects of anodic and of kathodic closure. My attention, however, has now 

 been directed to the observations of Hitzig, in which he finds that on minimal stimular 



