398 INDEPENDENT MUSCULAR IRRITABILITY. 



Immerse the whole of the muscle in a small vessel filled with 

 normal saline solution, and around the small vessel place a 

 large one, through which send a stream of hot water. 



By means of a thermometer, ascertain the temperature of 

 the saline solution close to the muscle. When the tempera- 

 ture rises to 38-40 C., the muscle is thrown into tetanus. 

 In this case the temperature of the whole muscle has been 

 raised at as nearly as possible the same time. 



Immediately that tetanus has set in, withdraw the muscle 

 from the saline solution. The tetanus will speedily pass away, 

 and the muscle will remain alive and irritable. 



Repeat the observation, but allow the muscle to continue at 

 the temperature of 40 for about two minutes. On removing 

 the solution, the muscle will still remain in a state of tetanic 

 contraction, as indicated by the position of the lever, and 

 from that contraction no relaxation will take place. No 

 stimulus, however strong, will be able to call forth any further 

 contraction. The reaction of the muscle will be found to be 

 acid, and its extensibility diminished. In fact, the muscle will 

 be found to have passed from a state of tetanus into a state 

 riynr morti*. 



VI. Thermal Stimulation of Nerves. 06s. X. 

 range the nerve-muscle preparation with the nerve dcpende 

 as in 06s. VII. 



Bring a hot surface to bear on the end of the nerve, or dip 

 the end of the nerve into a hot normal saline solution, or place 

 the end of the nerve in a small quantity of the normal saline 

 solution, the temperature of which gradually raise. 



In all cases contractions in the muscle will follow. 



rilAPTKR XXXI. 



URARI POISONING AND INDEPENDENT MUSCULAR 

 IRRITABILITY. 



uhn. I. Introduce beneath the skin of the back of a strong 

 frog u drop or two of a solution of urari. (The exact strength 

 of the solution and the dose required will depend on the source 

 from wh'ch the urari has been obtained.) In a short time the 

 frog will be found perfectly motionless, with its respiration 

 :n rested, but its heart still beating. 



Lay bare the sciatic nerve in the thigh, slip under it a pair 

 of electrodes connected with an induction coil, and stimulate 

 the nerve with an interrupted current, taking care that there is 



