1870.] Dr. C. B. Radcliffe on Animal Electricity. 



27 



tonus only, but in cathelectrotonus also. It would seem, indeed, that the 

 only difference between anelectrotonus and cathelectrotonus in this respect 

 is, that this suspension is a little less complete in cathelectrotonus than in 

 anelectrotonus, a lesser " stimulus " serving to cause action in the former 

 state than in the latter. It would even seem that any proper exaltation of 

 activity is to be met with in anelectrotonus rather than in cathelectrotonus. 

 Such are the conclusions respecting the modifications of the activity of the 

 nerve in electrotonus which are believed to be warranted by all the facts, 

 old and new alike. 



Nor is the increase of contraction detected by the myograph in cath- 

 electrotonus a sufficient reason for concluding that the irritability of the 

 nerve and muscle is exalted in this state ; on the contrary, this increase 

 may be nothing more than the natural consequence of the altered electrical 

 condition in cathelectrotonus. In ordinary muscular action, the state of 

 elongation or relaxation is believed to be caused by the mutual attraction 

 of the charges of opposite electricities disposed upon the two surfaces of 

 the sheaths of the muscular fibres, this attraction compressing the sheaths 

 at right angles to their surfaces ; in ordinary muscular action the state of 

 contraction is believed to be brought about by the discharge of the charges 

 which caused the opposite state of elongation, this discharge leaving the 

 fibres free to obey, as simple elastic bodies, the attractive force inherent in 

 the physical constitution of their molecules. In cathelectrotonic muscular 

 action, on the other hand, it is believed that the state of elongation may 

 be greater than that which is natural to the fibres (after removal from the 

 body, at least), because the charge communicated from the negative pole to 

 the fibres is greater than the natural charge of the fibres, the artificial 

 charge to the outside of the sheaths inducing an equivalent charge of the 

 opposite electricity on the insides, and so causing increased elongation by 

 increasing the compression to which the sheaths are subjected between 

 these two charges ; and that the contraction may be increased, because 

 contraction, according to this view, is only the return of the fibres, by 

 virtue of their elasticity, from the previous state of increased elongation. 

 The case supposed is precisely that which may be imitated in every 

 particular upon a narrow band of thin india-rubber sheeting, coated with 

 gold-leaf on its two surfaces within a short distance of their edge, or else 

 wetted to the same extent simply with water, and by charging and dis- 

 charging in turn ; for as the charge is communicated the band goes on 

 elongating until the charge has reached its maximum, and when discharge 

 is brought about there is sudden shortening, the degree of shortening being 

 always commensurate with the previous degree of elongation. What happens 

 is that which is supposed to happen in ordinary muscular action and in cath- 

 electrotonic muscular action also, if only the effects of the smaller charge and 

 discharge be made to stand for the first, and those of the fuller charge and 

 discharge for the last form of muscular action. It is of no moment, also, 

 whether the electricity used in charging be negative or positive. Whether 



