188 PHYSIOLOGY OF MUSCLES AMi M-RVKS. 



a spring against the wire, and replaces the slide. P>y 

 turning tlir disc the length 01 the inserted port ion of 

 rheorhoi-o! i.- altered. 



The whole arrangement is shown more clearly in 

 . 18, \\hieh may at t In-same time serve as a diagram 

 of tin- rxpiTinit-nts with muscles and nerves, to which 

 we arc now about to turn our attention. N r' r S is the 

 circular rheochord wire, through which the current of 

 the measuring apparatus passes in the direction of the 

 arrow ; /j, is a muscle, two of the points on the outer 

 surface of which, being connected with the multiplier, 

 afford a current, which is exactly compensated by that 

 portion of the current which branches off from the 

 rheochord at the points r and o. The particular length 

 o r of the rheochord wire at which this exact compen- 

 ?ation is accomplished, indicates according to the fixed 

 standard (the degree of compensation) the difference in 

 tension at the particular points on the muscle which are 

 t e.-t ed. This length may be found by turning the round 

 disc, together with the platinum wire, until the mul- 

 tiplier no longer indicates any deflection. By means 

 of a magnifying glass, the length of the inserted wire, 

 from its commencement at o to the reel at r, can be 

 read off on a graduated scale. 



