596 FUNCTIONS OF THE CEREBRO -SPINAL NERVOUS SYSTEM. 



two or more elements included in it, and then with only one element, and electro- 

 tonus is set up by so doing; anelectrotonus in the limb and nerve on the one side, 

 cathelectrotonus in the limb and nerve on the other side. And this is what happens 

 when this is done. If there are two or more voltaic elements in the circuit the estab- 

 lishment of eleetrotonus, by closing the circuit, is attended bv the cessation of tetanus 

 in both limbs in the limb on the side of cathelectrotonus, as well as in the limb on 

 the side of anelectrotonus. If only a single element be employed in setting up elee- 

 trotonus by closing the circuit, the tetanus is suspended in the lirnb on the side of 

 anelectrotonus, but in the limb on the side of cathelectrotonus, instead of being sus- 

 pended, the tetanus is sometimes (not always) exaggerated. These are the' facts. 

 The electrotonic results vary in this manner with the strength of the electrotonizing 

 current. The tetanus is suspended alike in anelectrotonus and cathelectrotonus under 

 the action of the stronger currents, but not to the same degree, for on comparing the 

 results of the action of the stronger currents with those of the weaker, the inevitable 

 inference is that the contraction-antagonizing power of the weaker currents is less 

 marked than that of the stronger. And this is all that is to be learnt from this 

 method of inquiry, except this, that the contractions consequent upon opening and 

 closing the voltaic circuit continue for a longer time on the side of anelectrotonus 

 than on that of cathelectrotonus. 



The second method of inquiry differs from the first in the substitution of a couple of 

 rheoscopic limbs (one for each of the two electrotonic states) for the galvanoscopic 

 frog, and in the measurement of the movements of the gastrocnemius during eleetro- 

 tonus by an apparatus consisting of a platform with an insulating gutta-percha top 

 to it, a series of multiplying wheels, a graduated scale, an index, and a string which 

 has to be attached at one end to the tendo-Achillis, and at the other to a hanging 

 weight just heavy enough to put the gastrocnemius gently on the stretch, and which, 

 by resting at its middle in the grooved rim of the wheel by which the other wheels 

 are driven, obliges the index to move in face of the graduated scale this way or 

 that, as the muscle happens to lengthen or shorten. Where the object is to exhibit 

 the action of anelectrotonus, one of the rheoscopic limbs (the other is reserved for 

 the experiment in cathelectrotonus) is fixed on the platform by passing a pin through 

 the knee-joint into the gutta-percha top, and then, after tying the string of the meas- 

 uring apparatus to the tendo-Achillis, and arranging the sciatic nerve so that it lies 

 across the voltaic poles, with the anode next the muscle, a drop of solution of salt is 

 applied to the nerve between the anode and the knee, or else the action of feeble fara- 

 daic currents is brought to bear upon the same spot. Where the object is to exhibit 

 the action of cathelectrotonus. the same arrangements are made for the other rheo- 

 scopic limb, with the single difference, that the cathode, not the anode, is now next 

 the muscle. And this is all that has to be done in either case, except to wait until the 

 muscles are slightly tetanized, and then to set up the state of eleetrotonus by closing 

 the voltaic circuit, first with two or more elements included in it, and then with one 

 element only. 



And this is what happens: In the case of the limb which is under the action of 

 anelectrotonus, the setting up of the electrotonic state is seen to have the cH'i-ct of sus- 

 pending the tetanus, and of causing, in addition, the index of the measuring appa- 

 ratus to move in a way which plainly shows that the gastrocnemius is slightly elon- 

 gated, and the only difference between the action of the stronger and weaker electro- 

 tonizing currents is in this, that tin- muscular elongation produced by the latter is 

 somewhat less marked in degree. 



In the case of the limb which is under the action of cathelectrotonus, the results 

 are the same as those which were noticed under the action of anelectrotonus, if two 

 or .more voltaic elements were employed in producing the electrotonic state. The 

 tetanus is suspended in both cases alike, and in both cases alike there is also muscular 

 elongation to the same degree even. But the results are not the same when a single 

 voltaic element is made use of in producing the electrotonic state, for in this case, 

 instead of being suspended, the tetanus, as is plainly seen by the movement of the in- 

 de\ of the apparatus, is often exaggerated to a considerable degree by the eleetrotonus. 



These, then, are the facts which are brought to light by carrying out these methods 

 of inquiry, and the question is how to account for them. How is the suspension of 

 tctauu-, and the muscular elongation consequent upon eleetrotonus, to be accounted 

 for? What is the explanation of the exaggeration of tetanus which may happen in 

 cathelectrotonus? How is it. that anelectrotonus has a greater power of suspending 

 contraction than cathelectrotonus? Why do the contractions consequent upon open- 

 ing and closing the voltaic circuit come to an end sooner under the action of cathelec- 

 trotonus than under that of anelectrotonus? And these questions are not looked upon 

 as unanswerable. 



