PHYSIOLOGY OF MOVEMENT. 



711 



When a single induction shock is allowed to pass through the motor 

 nerve of a muscle, the muscle at once gives a single short contraction. 

 The phenomena of such a muscular contraction may be best studied on 



5>F 



Fig. 275.— The Nerve-Muscle Preparation. (Stirling.) 

 F, lower third of femur ; S, sciatic nerve ; I, tendon of gastrocnemius muscle. 



the gastrocnemius muscle of the frog. Various contrivances have been 

 devised for graphically representing the results of the muscular 

 contraction. The simplest method is to support the knee-joint of 

 a frog's leg in a clamp, connecting the tendon of the gastrocnemius by 



Fig. 276.— Arrangement of Apparatus in Conducting Experiments on 

 Nerve and Muscle. (Stirling.) 



B, galvanic battery ; K. electric key in primary circuit : P, primary coil of induction machine ; 

 S, secondary coil of induction machine from which the current is conducted, when the key, K', is open, to 

 the electrode, E, on which rests the nerve, u : the muscle, M, is supported by a clamp, under a glass shade, 

 its tendon being connected bv a thread with a lever, L. writing on the smoked surface of a revolving 

 drum. The time-marker, TM, is included in the primary circuit, so that when the current passes through 

 P, by closing the key, K, it also traverses the electro-magnet of the time-marker and causes a record of 

 the instant of stimulation to be made on the surface of the drum. S, stand supporting moist chamber ; 

 W, weight by which muscle is extended, and which is lifted in the contraction. 



means of a thread to a lever, which records its movements on a rapidly 

 moving surface. If a single induction shock is then passed through the 

 sciatic nerve or directly applied to the muscle the so-called muscle 

 curve will be obtained (Pigs. 275 and 276). 



