378 ELECTRO-PHYSIOLOGY CHAP. 



velocity of the excitatory wave, then on exciting a muscle at 

 any given point the excitatory wave would already, after the 

 period of latent excitation, have traversed a tract of 45-92 

 mm. in the fibres, before contraction began at the seat of excita- 

 tion. Moreover, the vast difference that exists, according to 

 Bernstein, in the length of the two waves, would also come into 

 consideration. While the excitatory wave is about 10 mm. 

 long, the wave of contraction ranges between 198 and 380 

 mm. This last statement, however, needs consideration when 

 it is recognised that each contracted fibre point must be 

 regarded as " excited," and on the other hand admitted that 

 negativity is the galvanic expression of excitation. The first 

 assumption is essentially restricted by the fact that in all recent 

 experiments the latent period is found to be much shorter than 

 was formerly supposed. Moreover, F. S. Lee (I.e.) has recently, 

 by means of the capillary electrometer, found considerably higher 

 values for the duration of the wave of excitation than any 

 previous observer, so that no doubt remains that, at least in 

 fresh muscle, "electrical differences of potential, which are 

 associated with contraction, are demonstrable for a much longer 

 period than had previously been concluded." This also agrees 

 with the idea that the electrical wave falls in the latent period 

 of the contraction, and (as a whole) outlasts it (F. S. Lee). The 

 values found by Lee for the duration of the wave of excitation 

 are in fact of the same order as the duration of the contraction 

 (0-05-0-26 sees.) 



It thus appears as though clu Bois-Reymond's interpreta- 

 tion of the secondary contraction was after all the only 

 adequate and possible conclusion since it was shown that 

 with each single excitation the demarcation current of a muscle 

 underwent a very rapid negative variation, which could be 

 excited by a nerve bridging over the longitudinal and transverse 

 section, provided the preparation were sufficiently excitable. 

 This explanation necessarily underwent considerable modifica- 

 tion when the justice of Matteucci's original contention was 

 established, viz. that the appearance of the secondary contraction 

 is independent of the position of the nerve on the primary 

 muscle, since " parelectronomic " gastrocnemii, when excited from 

 the nerve, were also able to excite a secondary preparation, the 

 nerve of which bridged the longitudinal and natural transverse 



