190 ANIMAL PHYSIOLOGY. 
strength, according to the parts of the muscle connected by the 
electrodes. The strongest is that resulting when the superfi- 
Fie. 187.—Representation of electrical currents in a muscle-rhombus (after Rosenthal), 
cial equator and the transverse center are connected; and it is 
found that the nearer these points are approached the stronger 
the current becomes, as is indicated by the greater extent of 
swing of the galvanometer needle. In connection with these sur- 
prising phenomena, one naturally inquires whether such a mus- ° 
cle-current, for such it must be, is natura] or artificial. Does 
such exist in a living muscle in its position in the body, or has 
the injury done to a muscle in its preparation by section, re- 
moval from the usual conditions of nutrition, and such like 
changes, been the cause of the current ? 
After much investigation, by some of the ablest physiolo- 
gists of the day, different answers are returned to these queries. 
Du Bois-Reymond maintains that such currents are natural, 
and may be obtained from muscle contracting in situ ; while 
Hermann and others believe that such a current is owing to 
the injury done by the section, and that the current from the 
equator to the poles of the section is due to the fact that the 
injured part is negative to the uninjured region. 
It is a fact that if the current be led off from an exposed 
muscle prior to section, it is relatively very weak. Further, 
the electrodes placed on the uninjured ventricle of an animal’s 
