iv ELECTROMOTIVE ACTION IN MUSCLE 425 



produce mutual disturbance or neutralisation, so that the effect 

 on the superposed secondary nerve would be abolished, which is 

 not the case when with rhythmical, artificial excitation of the 

 nerve the collective elements respond in the same phase with a 

 uniform reaction. More recently Hering (55) and Briicke have_ 

 formulated a similar theory, and the latter expresses the relation 

 figuratively by contrasting the artificial excitation from the nerve 

 as a " volley," with the irregular discharge or " platoon fire " from 

 the central organ. The inefficacy of the primary tetanus pro- 

 duced by chemical excitation of the nerve, with regard to second- 

 ary action, may be explained in the same manner. " If we 

 imagine the secondary action of the muscle to proceed, not from 

 a single muscle-fibre, but always from "groups of fibres, and that 

 in every such group the waves of variation run parallel with 

 each other in no definite order, we have the conditions which 

 result in negation of the external effect, since the neutralisation 

 of the differences in electrical potential, which are the sole cause 

 of all secondary excitation, proceeds in the muscle from one fibre 

 to the other, from each negative point of the one to the less 

 negative, or positive, of the adjacent fibre" (Klihne, 50). Hence 

 it only remains to find the rationale for the early expiration of 

 secondary tetanus, or appearance of the secondary initial twitch, 

 with the rhythmical " volley " of electrical, or mechanical, excita- 

 tion. This presents no difficulty, provided the conditions of the 

 appearance of the primary initial twitch, and more particularly 

 its dependence on the intensity and frequency of the tetanising 

 stimuli, are kept in mind. According to the capillary electro- 

 meter and telephone, the intensity of the electrical variations of 

 the muscle declines very rapidly, and in each case much earlier 

 than the contraction. If in addition to this the stimulation- 

 frequency is considerable, we have sufficient ground for the brief 

 duration of the secondary tetanus. 



There is yet another factor to which Klthne (I.e. p. 68) first 

 drew attention. A striated muscle notably presents no physio- 

 logical entity, since at least two functionally distinct kinds of 

 fibres enter into its composition. It only requires a different 

 tempo in the rate of alterations of velocity in the dark (red), 

 slowly reacting fibres to that of the quick, light fibres, to produce 

 such interference between the waves of variation, that no differ- 

 ence of electrical potential at the surface remains to excite the 



