486 ELECTRO-PHYSIOLOGY CHAP. 



pensation of the strong entering current which under these con- 

 ditions is almost invariably present. The frog was usually 

 slightly curarisecl to the point of immobility immediately 

 before the experiment, since it seemed probable that the effects of 

 excitation would be seriously weakened if the poisoning had 

 occurred longer before, even if the circulation was normal, and 

 the heart vigorously beating. In agreement with Hermann and 

 Luchsinger, we found that the glossopharyngeal nerve acted 

 like the hypoglossal, and there was at most a difference of 

 degree in favour of the former. Since this is much more 

 quickly and conveniently prepared, the following experiments are 

 almost wholly based upon it. In normal, powerfully developed, 

 entering rest currents, we invariably found as the effect of 

 excitation of the nerve a monophasic, negative variation, the 

 magnitude of which is dependent, as we have seen, on the force of 

 the compensating current ; this makes itself evident a short 

 time (13 sees.) after the beginning of the excitation, and often 

 reaches very considerable proportions. We never, however, 

 observed reversal of a strong normal current in consequence of 

 excitation. As a rule, after long protracted excitation of the 

 nerve, the return swing of the magnet begins while it is still in 

 progress, and oscillations are again to be observed frequently, the 

 back swing being interrupted by renewed impacts in the direction 

 of the negative variation. If the exciting circuit is opened at 

 the moment when the magnet is on the point of turning, or a 

 little earlier, the development of the original current follows 

 more quickly than when the excitation is continuous ; it is also 

 evident that the backward phase of the negative variation 

 follows regularly with increasing rapidity ; and it is equally the 

 rule that the original current of rest is strengthened by excita- 

 tion, as was stated by Hermann. In our experiments, however, 

 this positive " after -variation " was never stronger than, or 

 even approximately as strong as, the preceding negative variation. 

 Under normal conditions we have only seen this last introductory 

 positive phase on a few occasions, and can therefore as little 

 attribute to it, as to the positive after- variation, the significance 

 attached to it by Hermann ; according to our experiences the 

 negative variation of the incoming current of rest has far more 

 the appearance in every case of the undoubtedly characteristic 

 effect of excitation, while the positive effect on the other hand 



