328 PRESENT STATE OF ORGANIC ELECTRICITY. 



with which it can be removed by any fluid which corrodes or 

 acts upon the muscular fibre, or by the knife.* 



The general Muscular Current. Nobili discovered, by 

 means of the galvanometer, that a current passed from the 

 toes towards the head of the frog. If the animal be deprived 

 of its skin, and bent backwards so that its feet dip into one 

 vessel and its snout into another, the vessels being filled with 

 a saturated solution of common salt, and connected by the 

 electrodes, the needle will indicate a current in the galvano- 

 meter wire from the head to the feet. According to Du Bois 

 Eeymond, the general current may, by certain precautions, be 

 detected even in the undissected frog, although the circuit is 

 partially closed by the skin. This current is the resultant of 

 the currents of all the individual muscles of the frog ; for Du 

 Bois Eeymond found, firstly, that in some muscles the cur- 

 rents set from head to feet, in others in the opposite direction ; 

 secondly, that the electromotor power of a muscle is directly 

 as its length and thickness ; and, thirdly, that if two muscles 

 are opposed to one another in a circuit, the thicker or the 

 longer overcomes the other. 



This general muscular current must therefore exist in every 

 animal possessing muscular arrangements, at least in the four 

 vertebrate classes. It does not, however, necessarily assume 

 the same general direction in all.f 



Electric condition of a Muscle during Contraction. This 

 condition has not yet been accurately determined. Matteucci 

 observed, that when two prepared frog's limbs are so arranged 

 that the nerve of the one lies across the muscles of the other, 

 muscular contraction of the latter induces contraction of the 



* The muscular current is investigated at great length, historically and 

 experimentally, in the second and third chapters of section iii. of Du Bois 

 Raymond's Untersuchungen. 



f The fourth chapter of section iii., in the first part of vol. ii. of the Un- 

 tersitchungen, treats " Of the influence of Contraction on the Muscular Cur- 

 rent." 



