I2 6 APPENDIX 



500,000 ohms, so that a cell of 2 volts would send only '000,000,4 of 

 an ampere through it. A cell of Char a of about the same length and 

 of less diameter than this allows considerably more current to flow through 

 it, as indicated by the increased deflection of the galvanometer. From this it 

 follows that either living protoplasm is a better conductor than egg-albumin, 

 or more probably that the cell-sap and moist cell- wall have a higher con- 

 ductivity than either protoplasm or egg-albumin. 



In any case the resistance offered by protoplasm to the passage of 

 an electric current is partly due to the electrolytic reaction, and is 

 dependent upon the quantity and quality of the electrolytic salts in 

 solution, decreasing to a certain extent with increasing concentration. 

 The fact that previous electrical excitation may render a weaker current 

 capable of stopping streaming may be merely the result of an increased 

 conductivity of the protoplasm, produced by the liberation of electrolytic 

 salts, allowing more current to pass, and hence increasing the shock-effect. 

 Since, however, the same effect may be produced when single currents 

 of extremely short duration are used, it seems more probable that it is 

 actually partly due to an increased excitability of the protoplasm produced 

 by the previous sub-maximal stimulation. 



