GRAPHIC REGISTRATION OF MUSCULAR CONTRACTION 



55 



Helmholtz (1850-1852), devised a recording apparatus which he desig- 

 nated as a myograph. This instrument has subsequently been modi- 

 fied by Pfltiger, Fick and Du Bois-Reymond. It would lead us 

 altogether too far to give even a tolerably accurate description of these 

 and other graphic appliances, and hence, it may suffice to say that the 

 registration of the contraction of muscle necessitates first of all a 

 means of holding the muscle, secondly, an outfit for recording its 

 movements, and thirdly, a surface upon which this record may be 

 made. One end of the freshly excised muscle is fastened in a station- 

 ary clamp, while the other is connected by means of a string with a 

 writing lever placed horizontally underneath it. This lever should be 



FIG. 26. A METHOD USED TO REGISTER MUSCULAR CONTRACTION. 

 St, stand for holding of clamp C and writing lever. WL, the muscle M is attached to 

 the lever by means of a small hook and string. The lever is counterpoised by weight W '. 

 The stimulation is effected through the electrodes, S. The speed of the kymograph K 

 may be varied by fan F. 



properly counterpoised by weights or tension springs so as not to 

 extend while it rests. Moreover, the muscle should be surrounded by 

 a small bell jar so as to be able to keep it under proper conditions of 

 moisture and temperature. The recording surface generally employed 

 to-day, consists of a sheet of glazed paper which is attached to the 

 cylindrical drum of a kymograph and is then evenly covered with soot 

 by rotating it in a broad gas flame. The drum carrying the blackened 

 paper, is moved by clockwork at different speeds, the velocity of its 

 movement being indicated in seconds by a chronograph which is ad- 

 justed underneath the muscle lever. If the rotation is rapid, an ordi- 

 nary tuning fork may be permitted to register its vibrations below the 

 myogram. 



