CAUSES AND PHENOMENA OF MOTION. 



23 



ratus (Fig. 275), which consists of a somewhat flattened glass cylinder a, 

 drawn abruptly to a point and fitted to a socket capable of movement and 

 attached to a stand A, so that it can be raised or lowered as required. The 

 lower portion of the cylinder is filled with china clay moistened with 

 saline solution, part of which projects through its drawn-out point, the 

 rest of the cylinder is fitted with a saturated solution of zinc sulphate 

 into which dips a well amalgamated piece of zinc which is connected by 

 means of a wire with the galvanometer. In this way the zinc sulphate 

 forms an homogeneous and non-polarizable conductor between the zinc 

 and the china clay. A second electrode of the same kind is, of course, 

 necessary. 



In such a regular muscle prism the currents are found to be as 

 follows: 



J 



FIG. 276. Diagram of the currents in a muscle prism. (Du Bois Reymond.) 



If from a point on the surface a line the equator be drawn across 

 the muscle prism equally dividing it, currents pass from this point to 

 points away from it, which are weak if the points are near, and increase 

 in strength as the points are further and further away from the equator; 

 the strongest passing from the equator to a point representing the middle 

 of the cut ends (Fig. 276, 2); currents also pass from points nearer the 

 equator to those more remote (Fig. 276, 1, 3, 4), but not from points 

 equally distant, or iso-electric points (Fig. 276, 6. 7, 8). The cut ends 

 are always negative to the equator. These currents are constant for some 

 time after removal of the muscle from the body, and in fact remain as 

 long as the muscle retains its life. They are in all probability due to 

 chemical change going on in the muscles. 



The currents are diminished by fatigue and are increased by an in- 

 crease of temperature within natural limits. If the uninjured tendon be 

 used as the end of the muscle, and the muscle be examined without re- 

 moval from the body, the currents are very feeble, but they are at once 

 much increased by injuring the muscle, as by cutting off its tendon. The 

 last observation appears to show that they are right who believe that the 

 currents do not exist in muscles uninjured in situ, but that injury, either 



