146 



ELECTRO-PHYSIOLOGY 



CHAl'. 



contraction wave in two different points of the muscle (frog's 

 gracilis). In the case of a muscle with parallel fibres, locally 

 excited at one end only, the obvious consequences will be a con- 

 traction (expansion) of the part excited, which travels at great 



Fio. 66. Velocity of contraction wave in muscle. The magnitude of interval between the two 

 curves (of expansion) is the measure. (Marey.) 



speed from the seat of excitation along the entire length of the 

 muscle. Two given points in the continuity of the muscle will 

 contract at different times, one after the other, and thus by means 

 of two levers, each of which rises with the expansion of a given 

 section of the muscle, the curve of expansion in both sections can 

 be recorded upon a suitable myograph (Fig. 70). From the 

 magnitude of the interval between the two curves standing upon 

 the same abscissa, it is easy to calculate the rapidity at which the 

 wave of contraction is transmitted (Fig. 66). 



Similar results to those of Aeby 

 were obtained by v. Bezold, 1861 

 (2), but with quite a different method. 

 He fixed a muscle with parallel fibres 

 lightly between two corks at its 

 centre, so that direct transmission of 

 changes in. form was prevented, but 

 not the propagation of the excitatory 

 process ; the lower part only (Fig. 67) 

 recorded its contraction, and thus 

 the time elapsing between an ex- 

 citation at the upper end, and the beginning of the twitch at 

 the lower, was determined ; this would obviously correspond with 

 the rapidity of transmission from the excited point to the first 

 section beyond the clamp. The experiments of Aeby and v. 

 Bezold gave the rapidity of transmission in striated frog's muscle 



Fn;. 'i7. Rate of transmission of excita- 

 tion in muscle, (v. Bezold' s method.) 



