380 Dr. C. B. Radcliffe's Researches in Animal Electricity. [Apr. 8, 



IV. On the Motor Phenomena ascribed to the action of the "Inverse 

 and Direct"" Voltaic Currents. 



When a voltaic current is so made to pass through the two hind limbs 

 of a prepared frog that the current is "inverse" in one limb and " direct" 

 in the other, it is found that the closing and opening of the circuit may or 

 may not be attended by contraction, and that the presence or absence of 

 contraction may or may not obey a similar rule in the two limbs. The 

 facts admit of being arranged in three stages, thus : — 







The limb in which the cur- 

 rent is " Direct." 



The limb in which the cur- 

 rent is "Inverse." 







On closing 

 circuit. 



On opening 

 circuit. 



On closing 

 circuit. 



On opening 

 circuit. 



Stage I. When 

 the electricity acts 



(a) With a 

 weak battery. 



Contraction. 



0. 



Contraction. 



0. 



similarly 'upon the 

 two limbs. 



(b) With a 

 strong battery. 



Contraction. 



Contraction. 



Contraction. 



Contraction. 



Stagell. When 



1st period. 



Contraction. 



0. 



Contraction. 



Contraction. 



the electricity acts 

 differently upon 



2nd period. 



Contraction. 



0. 



0. 



Contraction. 



the two limbs. 



3rd period. 



0. 



0. 



0. 



Contraction. 



Stage III. When 

 the electricity is 

 again made to act 

 similarly upon the 

 two limbs by re- 

 versing the posi- 

 tion of the poles. 



{a) With a 

 weak battery. 



Contraction. 



0. 



Contraction. 



0. 



(b) With a 

 strong battery. 



Contraction. 



Contraction. 



Contraction. 



Contraction. 



In seeking to account for these facts, the "direct" and "inverse" cur- 

 rents are not the only agencies which have to be taken into consideration. 

 If the limbs were perfectly sufficient conductors, the sole agencies at work 

 might be these currents ; but instead of being very good conductors, the 

 limbs are, in fact, non-conductors rather than conductors, opposing a re- 

 sistance to the current of about 40,000 B.A. units (a resistance nearly 

 seven times that of the whole Atlantic Cable) ; and the result of closing the 

 circuit with them is this- — that each limb is found to be charged with the 

 free electricity which is present at the poles when the circuit is open, and 

 which would be entirely discharged if the place of the limbs were supplied 

 by a perfectly sufficient conductor. The case is one in which, in accord- 

 ance with the investigations of Mr. Latimer Clarke on the tension of the 

 voltaic circuit, each limb is found to participate in the charge of the pole 

 nearest to it, the charge being positive in the limb in which the current is 

 inverse, and negative in the limb in which the current is direct, the tension 

 of the charge in each limb diminishing regularly from the pole where it is 

 highest, to some point midway between the poles, where it is at zero ; the 



