242 RESEARCHES ON SECONDARY ELECTROMOTIVE 



This muscle, stretched by the clamping of the pelvis and tibia, 

 lies horizontally with its borders directed upwards and downwards. 

 As the muscle tapers away by termination of fibres towards its 

 lower attachment, I place the lower electrode at the junction of 

 its middle and lower thirds, the upper one cm. below the upper 

 end on the wide surface of the muscle. Exactly opposite both these 

 electrodes, on the other wide surface of the muscle, I place the 

 galvanometer electrodes one opposite each. Midway between 

 these two, on the same surface, a third galvanometer electrode is 

 applied. In rapid succession, the lower and upper electrodes, or 

 the lower and middle, or the middle and upper can be thrown 

 into the galvanometer circuit, so that alternately the whole of the 

 intrapolar tracts, or only the lower or only the upper half of the 

 muscle is in circuit. All the electrodes are tube electrodes. I use 

 the whole current of 7 or 8 Daniells for stimulation. The period 

 of stimulation is 5 sees., the ' transmission time ' -026 to -034 sec. 

 A current of this strength, with this period of stimulation with 

 a fresh, well-excitable muscle and electrodes arranged as above, 

 gives strong positive anodic and weak negative kathodic po- 

 larisation. 



If immediately after opening the stimulating current I throw in 

 the lower half of the intrapolar tract next the stimulating anode, 

 I get a strong positive polarisation current ; if I throw in the upper 

 half next the stimulating kathode, I get a weak negative polarisation 

 current. If, finally, after opening the stimulating current I throw the 

 whole of the intrapolar region into the galvanometer circuit, this 

 gives a polarisation current corresponding to the difference between 

 the positive anodic and the negative kathodic polarisation, making 

 allowance for the change of resistance caused by the introduction of 

 a longer tract of muscle. Naturally it would be best if after one and 

 the same stimulation the polarisation of all three tracts could be 

 measured separately, but simultaneously. As this is impossible, it 

 is necessary to make several experiments on the same muscle. Each 

 preceding experiment influences that which follows it. This cir- 

 cumstance only changes to some extent the strength, not the 

 direction of the individual polarisation currents. In these experi- 

 ments we have to deal not with subtle but with relatively substantial 

 phenomena. To eliminate the influence of the order in which 

 the three tracts are investigated, either researches are made with 

 several muscles in different order, or a series of experiments is re- 

 peated in reversed order on the same muscle, as was partly the case in 



