DEGENERATIVE REACTIONS OF MUSCLE AND NERVE. 673 



noted that the muscles supplied by dying nerves and also the muscles of a curarized 

 animal respond less readily to a rapidly interrupted faradic current than fresh 

 non-curarized muscles. According to Neumann, it is the longer duration of the 

 constant current, as contrasted with the momentary closing and opening of the 

 induced current, that permits the possibility of contraction. If the constant 

 current be interrupted with the same rapidity as the faradic, it also will be 

 ineffective. On the other hand, the induced current can be made effective 

 if it be permitted to continue in action for a longer time. This can be accom- 

 plished in the sliding apparatus by keeping the primary circuit closed, and 

 raising and depressing the induction-coil upon the slide. By this means slowly 

 increasing and diminishing induced currents are generated that act energetically 

 in causing contraction of curarized muscles. Therefore, in the stimulation of 

 muscle and nerve, not alone the strength, but also the duration, of the current 

 must be taken into consideration, just as the deflection of the magnetic needle 

 is dependent upon both factors. According to E. Remak, however, the muscle 

 reacts, nevertheless, to individual induced shocks, when the reaction of degenera- 

 tion is present, and with a contraction of slower evolution, but this reaction is 

 no longer demonstrable after the lapse of a short time. The muscle is, therefore, 

 not inirritable to the faradic current, but only exhausted with extreme readiness. 

 It must constantly recuperate after its exhaustion. 



The typical reaction of degeneration is characterized essentially by the following 

 points. For the muscle there is, on direct irritation, diminution to the point of 

 abolition of faradic irritability, with increase of galvanic irritability (from the 

 third to the fifty-eighth day), the latter diminishing, although with considerable 

 variations, from the seventy-second to the eightieth day. There is also a prepon- 

 derance of anodal closing contraction as compared with kathodal closing con- 

 traction. The contraction in the affected muscle takes place slowly; it is pseri- 

 taltic and limited locally, in contradistinction to the lightning-like contraction 

 of normal muscles. In the stage of diminished galvanic irritability the latent 

 period is prolonged fourfold, the duration of contraction twofold. For the nerve 

 there is diminution to the point of abolition of faradic and galvanic irritability. 

 If the reaction of the nerve is normal, while the muscle on direct stimulation with 

 the constant current exhibits the reaction of degeneration, the condition is de- 

 scribed as partial reaction of degeneration, which is constant in cases of progressive 

 muscular atrophy. In the presence of deranged sensibility in cases of tabes, the 

 sensory nerves have been observed to react in a manner analogous to the motor 

 nerves in connection with the reaction of degeneration. 



In rare cases the contraction of the muscle from the nerve on application of 

 the induced current exhibits also a sluggish vermicular course faradic reaction of 

 degeneration. In the case of paralyzed and degenerated muscles the motor points 

 may be found displaced further toward the periphery. The lessened thickness of 

 the muscle and the resulting increase in density of the current may be the cause 

 for this. 



Nerve-degeneration and nerve-regeneration are considered on p. 663. 



In the different forms of spasm, contracture or electrical spasm, the constant 

 current especially has been found useful. Under such circumstances patho- 

 logically increased irritability of the nerves or muscles is diminished through the 

 effects of anelectrotonus. Therefore, the anode should be applied to the nerve 

 or the muscle, or in case of reflex spasm upon those points that are discovered to 

 be the actual source of the pathological irritation. Uniform, feeble currents are 

 especially effective under such circumstances. Also the relaxing (inhibiting polar) 

 action is to be considered. The constant current may, however, exert a beneficial 

 influence also through its catalytic action, by means of which it removes irritants 

 at the seat of disease. Finally, it has often been observed, since the time of Remak, 

 that with the application of the constant current, voluntary control of the affected 

 motor apparatus is increased. In cases of spasm of central origin the constant 

 current may be applied even to the central organ. 



Faradization may be employed in cases of spasm to strengthen possibly 

 enfeebled antagonists. Under such circumstances faradized muscles in a state 

 of contracture are said to acquire increased extensibility, as the muscle is more 

 extensible in a state of active physiological contraction. 



In the treatment of cutaneous anesthesia, stimulation should be applied first 

 to the skin itself, the induced current being often applied by means of wire-brush 

 electrodes. In the employment of the constant current the kathode should be 

 applied to the insensitive area. It is even possible with strong currents to cause 

 vesication of the skin. When the lesion has possibly a central situation only the 

 43 



