THE CHANGE IN FORM 337 



cork one inch long and just narrow enough to be 

 held in the Gaskell clamp (Fig. 26). Smoke a 

 drum. Raise the drum off the friction hearing 



o 



by turning to the right the milled screw at the 

 top of the shaft. Fasten the end of a curarized 

 sartorius muscle to the cork plate by means of 

 two needles to the ends of which conducting 

 wires are soldered. Place the preparation in the 

 Gaskell clamp in such a way that the clamp 

 shall compress the equator* of the muscle suffi- 

 ciently to prevent the passage of a contraction 

 wave from one part of the muscle to the other, 

 but not sufficiently to prevent the passage of the 

 excitation. Let a second pair- of needle elec- 

 trodes rest on the muscle near the upper side of 

 the clamp. Fasten the clamp to the iron stand. 

 Connect the two pairs of electrodes to the end 

 cups of a pole-changer (without cross-wires), the 

 side cups of which are connected with the secon- 

 dary coil of an inductorium arranged for single 

 maximal induction currents. In the primary 

 circuit of the inductorium place the electro- 

 magnetic signal. Fasten the tibial end of the 

 muscle to a muscle lever. Bring the writing 

 point against the smoked surface exactly under- 

 neath the point of the electro-magnetic signal. 

 " Spin " the drum slowly. Place the writing 

 point of a vibrating tuning fork against the 



