52 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



part, the anchors have only to be rocked to one side or the other to complete the commu- 

 nication between the battery and one or the other of these pairs of electrodes. 



In experiments with the double myograph, in which the making of the 

 current is used to irritate, records are obtained such as are shown in Figure 18. 



FIG. 18. The making contraction starts at the kathode (after Biedermann). 



In these records the beginning of the tuning-fork waves shows the moment 

 that the current was made and the irritation given. In the experiment from 

 which record a was taken the anode was at the knee-end of a curarized sartorius 

 muscle and the kathode at the pelvic end i. e. the current was ascending 

 through the muscle. The lower of the two curves was that got from the 

 kathode half, the arrangement being that shown in Figure 15, and the lower 

 curve began before that got from the anode half; i. e. the contraction originated 

 at the kathode and spread thence over the muscle. In b the current was 

 reversed, and the upper curve was obtained from the kathode half and the 

 lower from the anode half; in this also the kathode end contracted first. 

 In the above experiments the making of the current was used to irritate, 

 and the muscular contraction began at the kathode ; in experiments in which 

 the breaking of the current was employed the opposite was observed, the 

 anode end being seen to contract first, regardless of the direction of the cur- 

 rent. 



If strong currents be used, the fleeting contractions which result from 

 opening and closing the current are followed by continued contractions, the 

 closing, Wundt's, and the opening, Hitter's tetanus, as they are called. These 

 continued contractions, which last for a considerable time, remain strictly 

 located at the region where they originate, and Engelmaun proved by his 



