388 Royal Society : — 



moved under the current of the relaxed muscle, but not to the 

 same distance from zero. In other \\'ords, the muscular current is 

 weakened but not changed in direction when the muscle passes 4nto 

 the state of contraction. 



In the experiment in which Prof. Matteucci sees an intensification 

 of the muscular current during contraction without any change in 

 direction, he takes a prepared frog, and after preserving a sufficiently 

 long portion of the sciatic nerve, he amputates the thigh above the 

 middle joint. Then, taking the lower portion of the amputated 

 thigh with the nerve attached to it, and })lacing the cut surface 

 against an electrode of the galvanometer and the uncut surface 

 against the other electrode, he watches the needle as it diverges 

 under the current of the relaxed muscle. After this, he brings about 

 a state of contraction in the muscle, by irritating the nerve with a 

 feeble interrupted current, and, looking at the needle, he sees it move 

 in the same direction as that in which it had already moved under 

 the current of the relaxed muscle. That is to say, the needle 

 shows, not weakening or change of direction, but actual intensifica- 

 tion. On repeating this experiment, the author finds that it is 

 most difl[icult to draw any safe conclusion from it ; for in a thigh 

 prepared in this manner it is almost impossible to keep the same 

 point of the cut transverse surface in steady opposition to the elec- 

 trode. Indeed, the necessary effect of contraction is to draw away 

 the cut end from the electrode, and in this way to interrupt the 

 entrance of the current of the contracted muscle into the circuit of 

 the galvanometer. The effect of contraction, moreover, is often to 

 bring upon the electrode portions of nuiscle which have not entered 

 into the state of contraction, and in this way the only current which 

 finds admission into the galvanometer may be that which is derived 

 from relaxed muscle. This is often the case, and hence the apparent 

 intensification of the muscular current during contraction, which is 

 now and then witnessed in tliis experiment (it is not always wit- 

 nessed), may, after all, be due to the irruption of additional quantities 

 of the current of the relaxed muscle into the galvanometer. At any 

 rate, the experiment is one from which it is most difficult to draw 

 any certain conclusions. 



In ordinary muscular contraction, then, there is good reason to 

 believe that the muscular current is enfeebled — enfeebled to a degree 

 approaching very closely to extinction ; and in i-iyor mortis all traces 

 of muscular current have disappeared. It appears, indeed, as if 

 muscular contraction were antagonized by the muscular current. 



In tracing out the history of muscular action from an electrical 

 point of view, the author proceeds, in the next place, to consider 

 the mode in which the muscular current is affected by the nerve- 

 current. In doing this, after describing the peculiarities of the 

 nerve-current, and relating a beautiful experiment of Prof. Du Bois 

 Reymond, in which it is seen that the nerve-current agrees with the 

 muscular current in exhibiting a positive loss of force during mus- 

 cular contraction ; he interprets the reactions which must take place 

 between the nerve-current and the muscular current by appealing to 

 the history of the electrical organ of the torpedo and its congeners. 



