136 



THE SIGNS OF LIFE 



[LECT. 



And yet, while we find reason to reject an appeal to water 

 currents (or " concentration currents "), as being the original 

 source of electrical effects that arise or are provoked in living 

 matter, we should be careful to remember that water currents 

 must actually play an important, if secondary part, in the com- 

 plicated molecular play of physiological action. Local action 

 implies local disintegration, raised osmotic pressure, attraction 

 of water, and electrical current. The water current is towards 

 the active spot ; the electrical current is from that spot ; we 

 must imagine it as a kationic current. 



80. Evaporation current. This first experiment should 

 serve as reminder to you that gradual shiftings of the galvano- 



FlG. 5-4- To illustrate evaporation currents. 



meter spot may, among other causes, be due to evaporation of 

 water, and to capillary currents thereby produced. The circuit 

 contains nothing but the galvanometer, and a pair of unpolaris- 



