OF VITAL PHENOMENA gi 



are induced, B a coil around a beaker, c a condenser, and 

 d a detector with which to observe any change in the oscillating 

 current. If the beaker is filled with a conducting solution the 

 oscillations are damped, as shown by the detector. If erythro- 

 cytes are placed in the beaker the oscillations are damped as 

 much as by 0.4 per cent NaCl solution. This remains the same if 

 the plasma membranes are destroyed by saponin. Since the con- 

 ductivity, as measured by the Kohlrausch method, is increased 

 ten times by the destruction of the plasma membranes, they seem 

 to be the chief cause of the low conductivity of the normal 

 erythrocytes. 



A third method for measuring the internal conductivity of 

 cells is the use of high frequency electric oscillations instead of 

 induction coil currents, in the Kohlrausch method (Hober, 

 1913 b). When an alternating current is passed through a solu- 

 tion, the cations move in one direction until the current changes, 

 then move in the opposite direction, arriving at their original 

 positions. The anions behave similarly. The distance traveled 

 by an ion is proportional to the duration of one phase of the 

 current, or inversely proportional to the frequency of the alterna- 

 tions. The higher the frequency the less the distance traveled 

 by an ion. When the frequency is ten million per second the 

 distance traveled by an ion is insignificant. The plasma mem- 

 branes stop very few ions directly, but stop or retard all of them 

 by the electric polarization produced by the stoppage of a few 

 ions. The less the distance that would be traveled by an ion, 

 the less the polarization, hence the very slight polarization when 

 high frequency oscillations are used. The conductivity measured 

 by means of high frequency oscillations is therefore practically 

 the same, whether the plasma membranes are present or absent. 

 It should be noted, while this line of reasoning is in mind, that the 

 conductivity of erythrocytes, measured by the Kohlrausch 

 method, using an induction coil with rapid interrupter, is too 

 high, and it is theoretically only with a direct current and non- 

 polarizable electrodes that the true conductivity may be meas- 

 ured. In actual practice the errors with the direct current are 

 usually so great that the Kohlrausch method is to be preferred. 



By means of the damping method, Hober found the internal 

 conductivity of frog's muscle that had been washed six hours in 



