106 GENERAL PROPERTIES OF LIVING TISSUES 



Fasten a curarized sartorius muscle by the middle 

 in the Gaskell clamp; the pressure should be 

 enough to prevent the contraction wave of one 

 part reaching the other part, but not great enough 

 to prevent the passage of the excitation. Place 

 the muscle vertical to the writing levers. Tie a 

 thread around the pelvic and tibial fragments 

 and fasten each thread to a muscle lever, so that 

 each half of the muscle may record its contrac- 

 tion independently of the other. Moisten two 

 strands of lamp wick with normal saline clay. 

 Tie one strand around each end of the muscle 

 and lay the free portion of the strands on the 

 toes of boot electrodes properly mounted. Note 

 which lever is connected with the cathodal end. 

 Make the current. If the muscle does not con- 

 tract, move the slider along the wire a short dis- 

 tance towards the positive post (so as to bring 

 a stronger current through the electrodes) and 

 make the current again. When both make and 

 break contractions are secured, see that the writ- 

 ing points record properly, and " spin " the drum, 

 but not too fast. As soon as the drum moves 

 steadily, make and then break the current. 



The moment of making and breaking the cur- 

 rent will be recorded by the electro-magnetic 

 signal. An instant later the muscle levers will 

 begin their record of the contractions. 



