374 



ELECTRO-PHYSIOLOGY 



CHAP. 



off by two cross-sections in close juxtaposition. If the fibres 

 in (p) are excited by momentary closure, the negative variation, 

 after a given period, reaches the element (d, M^ at the very 

 moment at which the first signs of the negative variation 

 appear in the galvanometer circuit. At the same moment, 

 however, the negative variation reaches its maximum in the 

 element (d, Jf 2 ) nearer to the point of excitation, while it has 

 already subsided at (d, 3f 3 ), a third element. 



" If the magnitudes of the negative variation are drawn as 

 ordinates over these and the intermediate elements of the muscle- 

 fibre, we obtain the curve (m, n, o), which represents the state of 

 electromotive change in the subjacent elements of the muscle 

 fibre." Bernstein designates the curve (m, n, o) the " wave of 

 excitation." It spreads like an undulation from the spot 



FIG. 118. Schema of the "excitatory wave." (Bernstein.) 



excited over the muscle fibre, in either direction, producing 

 successively in each element of the fibre the complete process of 

 the negative variation, so that the wave advances at its own 

 length as long as the negative variation continues. Bernstein 

 calculates the length of the wave at an average of 1 mm., from 

 his observations. 



If we sum up the results of all these experiments and 

 discussions on the negative variation in a parallel-fibred muscle, 

 provided with an artificial cross-section, it may be concluded 

 that, if one end of the muscle is excited by single induction- 

 shocks, while leading off from the other, a change is initiated 

 in the first segment concerned at a given interval after each 

 single stimulus, which interval corresponds with the distance 

 between the leading-off longitudinal contact and the point of 

 excitation. The change set up gradually increases, reaches its 



