X. Variation in the method of applying mechanical, 

 thermal and chemical stimuli. 



/. Appliances. Operating case; kymograph; myograph; 

 3 frogs. 



2. Preparation. Much interest will be added to these 

 experiments if a permanent record be made of the move- 

 ments of the lever when the muscle responds to a stim- 

 ulus. The most practical method of recording these 

 movements is to cause the lever point to trace them upon 

 a moving surface. It is customary to use a rotating cyl- 

 inder, upon which is fixed a glazed paper which may be 

 smoked in a gas flame. The kymograph wave writer 

 an instrument much used for this purpose, consists of a 

 metallic cylinder and a clock work for its propulsion, 

 (See Fig. 14.) 



Describe the structure of the kymograph giving fig- 

 ures. 



To prepare the kymograph for work. (See Appendix 

 A-6.) 



To curarize a frog. (See Appendix A-5.) 



j. Operation. To make a sartor ius preparation. After the 

 frog has come under the influence of the curare, pass a 

 blade of the fine scissors under the tendon of insertion 

 of the sartorius; cut it as close to the tibia as possible; 

 grasp the tendon with forceps and carefully lift it up, 

 cutting, with the scissors, the connective tissue which 

 holds the muscle in place; follow it as far as possible and 

 get as much of the tendon of origin as possible. Mount 

 this preparation by tying a thread to each terminal tendon, 

 and fixing one thread to the myograph clamp and the 



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