MUSCLE AND NERVE 



53 



ing lever placed in the same ordinate below the first. Pull upon the 

 strings to ascertain whether these levers interfere with one another. 

 Attach a weight of 10 grams to each. Make a small opening in the skin 

 over the upper part of each gastrocnemius muscle. Fasten the wires 

 from the secondary coil of the inductorium near the knee-joint one 

 on each side. Then complete the circuit by uniting the gastrocnemii 

 muscles by means of a short piece of flexible wire. 



Allow the drum of the kymograph to revolve very slowly. Record 

 the contractions of these muscles in the same ordinate until completely 

 fatigued. Note that the bloodless muscle is much more easily fatigued. 

 Explain. 



5. Smooth Muscle. Connect the secondary coil of the induc- 

 torium with the two outside posts of a moist chamber and attach two 

 shorter wires of medium thickness to the corresponding inside posts. 



FIG. 32. MOIST CHAMBER. 



S, Stand; M, muscle; E, electrodes; L, writing lever; TM, signal; K, simple key; PS, 

 inductorium; K', short-circuiting key. (Stirling.) 



Place a piece of filter-paper moistened with saline solution against the 

 inner surface of the glass cover. If the temperature of the room is 

 low, place a lighted alcohol lamp at some distance below the floor of the 

 moist chamber. Arrange the electric apparatus for stimulation with 

 single induction shocks. 



Obtain a preparation of smooth muscle tissue and fasten it in the 

 clamp at the end of the horizontal rod in the moist chamber. To its 

 other end tie a silk thread, which is then brought through the orifice in 

 the floor of the chamber and fastened to the writing lever directly 

 underneath the latter. The writing lever should be adjusted in a 

 horizontal position by moving it up or down. Do not tighten the after- 

 loading screw, because the lever should at first be able to move upward 

 as well as downward. Fasten the ends of the short wires in the top of 

 the preparation. Adjust a chronograph underneath the point of the 



