ill a moist cliamhcr. Kxamine the moi-t chamber; note the muscle 

 rlanip in which the I'ennir may In.- placed, ami the binding posts. 



Make diagram- of all the pieces <>f apparatus 



Adjust the muscle lever and moist chamher on the support and 

 arrange \oiir whle a]t])aratus in a convenient po-Hion for taking a 

 record of contraction. (See demonstration.) Diagram. 



MM. ('iirrcs f siin/le contraction, summation of twitches, and 

 t claims. Kach student is t preserve one set of record-, so two 

 recrd- should he made by a pair of students working t gether. 

 When the paper mi the drum is covered it should lie removed, 

 clearly labelled, shellacked, and hung up to dry; then the records 

 -hould be cut out and pasted in the laboratory book, with the descrip- 

 tion of the experiment. Always draw a base line under the muscle 

 curve before shellacking. The student's name and data of the experi- 

 ment -hould also be written on the record. 



a. Simjlc contraction. Connect the inductorium with two cells only 

 and push the coils near enough together to give a good single shock. 

 Set the drum on high speed and allow it to revolve after pre-sing 

 the writing lever and signal magnet lever lightly against the drum. 

 Take a record of a single twitch on the make of the current, and 

 another : n the break. Which is greater? Why? 



b. Summation of stimuli. Send in two shocks in rapid -uc- 

 ce--i<>n by making and quickly breaking, so as to obtain a curve 

 Allowing what happens when a muscle is stimulated at the height of 

 contraction. If you fail in obtaining the correct time interval be- 

 tween shock- the first time, try again. 



c. Incomplete tetanus. Repeat, making and breaking by hand in 

 rapid -ucccssion. Summation of -everal -hock- -hould be obtained, 

 giving an incomplete tetanus. 



I letter record- of incomplete tetanus can be obtained by mean- of 

 the spring interrupter. Study the instrument and make a diagram 

 "f it. Connect with an inductorium whose coils are so far separated 

 that only break shocks stimulate, and obtain record- -bowing dif- 

 ferent degree- of incomplete tetanus. 



d. ('omplete tetanus. I )e-cribe a curve of contraction with 

 letani/ing current, i.e., with interrupted laradic or induced current. 

 !><> not -timulate f r longer than ,} -econds. 



e. l-'atii/ne cnn-e. With very slow -peed of drum, fatigue the 

 inu-cle by prolonged tetanu-. Note the gradual relaxation in -pile 

 of 0'iitimied -limulation. When completely fatigued, allow to rest. 

 Wa-h with -alt -olntion. Then take curve- of single twitehe- with 



