viu. j QUINKE CURRENTS 133 



alive as to require a series of shocks to bring about summation 

 of effects, must be tested by tetanisation that cannot be passed 

 through the galvanometer, which, therefore, must be short cir- 

 cuited during the process. 



There is one more shape in which the fallacy of the elec- 

 trodes may appear, which, under certain conditions, may be 

 very deceptive indeed. The state of the electrodes, especially 

 if they have been long put up, may be such that anomalous 

 polarisation of one electrode may be present, with ordinary 

 polarisation of the other electrode. The seat of such polarisa- 

 tion may be between zinc and zinc sulphate, or between zinc 

 sulphate and saline clay. The deflection may be in one and 

 the same direction for both pairs of directions of tetanisation, 

 thus simulating the formula given above as characterising the 

 living state. Electrodes of this nature must not be used. 

 Electrodes prepared with ordinary care do not exhibit the fallacy. 



78. A future preliminary. A methodical examination by 

 the ABC method, of the polarisation effects produced by con- 

 stant and by induced currents passed through various electrodes 

 and electrolytes, would form a very useful preliminary exercise 

 introductory to the study of physiological polarisation. You 

 would find that some combinations are polarisable at both 

 poles, that others give only anodic or only kathodic polarisa- 

 tion, and prominent among these purely physical effects you 

 would find that by reason of anomalous polarisation the chief 

 physiological after-current the positive post-anodic action 

 current is exactly imitated, which things should not lead you 

 to imagine that the physiological effects are " merely physical," 

 but invite you rather to the further physical analysis of physio- 

 logical phenomena. 



79- Quinke currents. Currents of liquid through a porous 

 partition, e.g., a membrane through which osmose is taking 

 place, arouse electrical currents in the direction of the water 

 movement. Conversely, an electrical current passed through a 

 porous partition between two electrolytes causes a flow of water 

 in its own direction. This water transport, from anode towards 



