1915] 



MERRILL — ELECTROLYTIC DETERMINATION OF EXOSMOSIS 



535 



stone bridge and also for various concentrations of NaCl. 

 Thus 0.15 gram residue was obtained from 1500 cc. of the 

 media from illuminating gas-treated cultures. This is equiv- 

 alent to 0.10 gram in 1 liter, which in terms of NaCl would be 



65 



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Fig. 7. Conductivity curves of cultures (series 14) in distilled water 

 subsequent to treatment, as follows: No. 1, temperature of — 6 to 

 — 2°C., 1 hour, roots in tumbler; No. 2, temperature of — 6 to — 2°C, 

 2 hours, roots in tumbler; No. 3, temperature of — 6 to — 2°C, 3 hours, 

 roots in tumbler; No. 4, control — room temperature, roots in tumbler; 

 No. 8, control — room temperature, roots in tumbler. The plants were 

 23 days old at the time of treatment. The first reading was taken in 

 each case after the roots had been in the distilled water for the follow- 

 ing respective periods (cultures 1—3 were being treated during part of 

 that time) : No. 1, 1 hour and 47 minutes; No. 2, 2 hours and 29 

 minutes; No. 3, 3 hours and 45 minutes; No. 4, 3 hours and 6 minutes; 

 No. 8, 2 hours and 2 minutes. 



approximately N/500. The specific conductivity of N/500 

 NaCl is about 25 X 10~ 5 , the x value of which on the Wheat- 

 stone bridge is 85. The average final reading of the 6 cul- 

 tures treated with illuminating gas is 79.5. Hence the residue 

 in terms of NaCl would be in the neighborhood of N/500. 



