56 LABORATORY MANUAL OF GENERAL PHYSIOLOGY 



perishable. Try several until satisfactory results are obtained (cf. 

 Bayliss, p. 404, or Barnes, Sell and SpofFord, Zeit. verg. Physiol., 18: 282, 

 1932). Text p. 300. 



Fig. 4. — Nerve fibres to adductor and abductor in crustacean claw (cf. Barnes, Am. J. Physiol., 



107:447,1934). 



27. Effect of Temperature on Muscular Contraction. — Make a gastroc- 

 nemius preparation of the frog without the nerve. Bind the femur to 

 the L-shaped rod of the "muscle warmer" (supplied by instructor) with 

 iminsulated fine wire. Attach the tendon of Achilles to the muscle lever 

 by fine w^ire, the free end of which is attached to the binding post of the 

 lever to which one post of the inductorium is wired. Wire other post of 

 inductorium to L-shaped rod of warmer. Place 1 cc. of Ringer in the 

 glass cylinder and fix it in place. Arrange to stimulate muscle with a 

 maximum induction shock. Weight with 10 grams. Insert thermometer 

 in muscle warmer. With every change of temperature wait 5 mins. for 

 thermal adjustment. Immerse muscle warmer in a glass jar of water, 

 the temperature of which is adjusted with hot water or ice. Record 

 contractions on rapidly moving drum with electrical time record. Start 

 at room temperature and proceed to 0° at 2° intervals, then raise the tem- 

 perature taking records at 2° intervals until heat rigor sets in. Note 

 height and duration of contraction at each temperature (cf. Howell, 

 12th Ed., p. 31). If necessary, time may be saved by taking the records 

 on a slow drum without tuning fork. 



28. Effect of Curare. — Pith the brain but NOT the cord of a frog. 

 Slit the skin on the dorsal side of the left thigh. Expose the sciatic nerve. 

 Avoid injury to blood vessels. Insert a moist thread ligature xmder the 

 nerve and tie tightly around the thigh to stop circulation. Cover exposed 

 nerve with filter paper soaked in Ringer solution. Inject 3 or 4 drops of 

 curare solution into the dorsal lymph sac. The body will become limp 

 in about 10 mins. Suspend by a hook in the jaw. When tactile stimula- 

 tion of the right leg fails expose both sciatic nerves up to the vertebral 



