264 ELECTRO-PHYSIOLOGY CHAP. 



must be fresh, and as excitable as possible ; second, the current 

 must not be too weak, nor closed for too brief a period. As a 

 rule, 2 to 3 sees, closure was sufficient with the full strength of a 

 Daniell cell. After the first anodic wave of relaxation has run out, 

 the ventricle contracts in systole, next a peristaltic diastole sets in, 

 and so forth. If the current is broken shortly after the second 

 or third systole has begun, a diastolic wave, beginning at the 

 kathode, may frequently be seen to sweep over the entire 

 ventricle, i.e. diametrically opposite to the former direction. 

 Sometimes this may still be detected in the second and even 

 third diastole after the current has been opened, followed at the 

 point of peristaltic relaxation, if the pulsations continue, by a 

 diastole which seems to commence simultaneously all over the 

 ventricle. From this we may infer that the kathodic break, like 

 the anodic make, relaxation, propagates itself from cell to cell 

 (by conductivity) from its starting-point. This conclusion, 

 together with the fact that the first-named effect only occurs 

 plainly under the most favourable conditions, seems to exclude 

 the hypothesis that it is a manifestation of fatigue, produced by 

 persistent kathodic excitation. It is much more probable that we 

 are here in face of a characteristic and active reaction (equivalent 

 to the anodic closure effect) of tonically contracted cardiac 

 muscle. 



These facts relating to the effect of the electrical current 

 upon the cardiac muscle of invertebrate and vertebrate animals 

 may no less appropriately arrest our attention than the excitation 

 effects previously described in smooth muscle, since they form a 

 distinct contribution to our knowledge of the effects of the 

 electrical current. We see, in the first place, that the kathodic 

 make and anodic break contraction are by no means the only 

 visible effects of electrical excitation, but that an antagonistic 

 inhibitory effect also occurs occasionally during an existing state 

 of excitation, and expresses itself as the relaxation of a pre- 

 viously contracted part. Since, in the great majority of cases 

 relating to the electrical excitation of contractile structures, 

 the latter are in a state of comparative quiescence at the moment 

 of excitation, it is intelligible that nearly all observations 

 should refer to those manifestations of activity which it has 

 alone been usual to regard as excitation phenomena. But the 

 investigation of appropriate objects further shows that the 



