350 ELECTRO-PHYSIOLOGY CHAP. 



schema, in order " to arrive at what was common to all, or to the 

 last reduction that still preserves the type of the ending." 



In Scdamandra, where the motor nerve-endings consist entirely 

 of non-medullated, non-nucleated terminal fibres, embedded directly, 

 with no intermediate element, between the sarcolemma and the 

 contractile tissue, the simplest form = j , where the stronger 

 stem represents the last epilemmal, medullated nerve, the lines at 

 right angles being the intramuscular end-fibres, approximately 

 parallel with the fibres of the muscle. Asymmetrical forms = 

 |-> f ^~~> frequently appear, never the simple | form. As 

 against these, the " plates " of the higher vertebrates are chiefly 

 characterised by the bulging walls of the branches, studded with 

 small lobes, or humps. Here too, however, a closer inspection de- 

 tects the asymmetrical branching of the end-ratal (characteristic of 

 arborisation), "with sharp angles like a bayonet " ("never in the form 

 of a tuning-fork "). " This discloses another feature, to be interpreted 

 in the same sense, i.e. the arched and recurrent curvature of the 

 branches, their lateral or terminal prominences lying so close 

 together that they only embrace very small bridges of muscle." 

 " This arrangement presents every transition, from the simplest, 

 consisting of a single loop, curved on the surface and humped, to 

 the more circumscribed and labyrinthine plates, which form ex- 

 pansions with circular, elliptical, and oblong bases. The simplest 



schema therefore = (5 T, the more complex ^j ." To this 

 character of the terminal fibres Kuhne refers a peculiarity 

 in the excitatory waves impinging on them, " which is of some 

 importance to muscular excitation," since " in the never-failing 

 homodromous fibres no waves can advance in a parallel course 

 without exhibiting phasic differences." " In view of Bernstein's 

 remarkably steep, almost vertical decline of the wave of electrical 

 variation in nerve, the distances between the terminal fibres 

 running parallel with each other and the nearest root must be 

 sufficient to initiate a considerable P.D. between each pair of 

 points connected by a perpendicular." " Between these points, 

 which have diametrically opposite signs, if the wave of variation 

 is, in Bernstein's sense, heterodromous to the nerve current, there 

 is, however, muscle-substance, which must complete the circuit of 

 the potential." Kuhne thus imagines that a current completes 

 itself between opposite points of the terminal branches of ingoing 



