330 PRESENT STATE OF ORGANIC ELECTRICITY. 



not due to an increased resistance to conduction in the muscle 

 from its contracted condition is proved by placing the two 

 corresponding muscles of the same animal, one before the 

 other, in the same galvanometer circuit, but reversed so that 

 their currents are opposed to one another, and then tetanising 

 one of them, for when this is done the current of the other 

 acquires the ascendant. 



The negative deflection in the first form of the experiment 

 is due, therefore, neither to invasion of the galvanometer 

 circuit by the exciting current, nor to a change in the direction 

 of the ordinary current, nor to increased resistance to conduc- 

 tion. It is the result of the counter-current produced at the 

 platinum electrodes of the galvanometer during the passage of 

 the ordinary muscular current ; and this counter-current de- 

 flects the needle negatively as soon as the ordinary muscular 

 current begins to lose its influence on it through the annihil- 

 ating effect of the tetanus. The negative deflection is also in 

 proportion to the intensity of the ordinary current, and is, 

 moreover, increased by the negative effect of the parelectro- 

 nomic layer, which, according to Du Bois Eeymond, is not 

 affected by the act of contraction. 



The diminution or cessation of the ordinary muscular cur- 

 rent has been employed by Du Bois Eeymond to explain 

 certain curious experiments which he has latterly made. The 

 general muscular current of the frog sets, as has been stated, 

 from the toes to the head of the animal. Now, if one of the 

 legs of a frog be paralysed by cutting the sciatic plexus, the 

 feet being then placed in the two conducting vessels for the 

 electrodes of the galvanometer, and the animal tetanised with 

 strychnine, it is evident that the ordinary general current will 

 be diminished in the tetanised limb. Under these circum- 

 stances, the galvanometer indicates not only an increase of the 

 upward current in the paralysed limb, but a downward curi'ent 

 in the tetanised one. On the human subject a corresponding 



