1915] 



MERRILL ELECTROLYTIC DETERMINATION OF EXOSMOSIS 



555 



obtained from N/10 MgCl 2 plus N/20 CaCl 2 , while the 

 N/10 MgCl 2 plus N/100 CaCl 2 causes a rise higher than that 

 in the two curves just mentioned after the fifth day. It was 

 unexpected that N/20 CaCl 2 should exceed N/20 MgCl 2 in its 



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$ 40 



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 8 



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30 



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20 



15 



10 



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1 



3 



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7 

 Days 



9 



11 



13 



Fig. 



17. Conductivity curves of cultures (series 16) in distilled 

 water subsequent to treatment, as follows: No. 11, N/10 MgCl 2 , 75 

 hours; No. 12, N/20 MgCl 2 , 75 hours; No. 13, N/10 CaCl 2 , 75 hours; 

 No. 14, N/20 CaCl 2 , 75 hours; No. 15, N/10 MgCl 2 plus N/10 CaCl 2 , 

 75 hours; No. 16, N/20 MgCl 2 plus N/20 CaCl 2 , 75 hours; No. 17, 

 N/10 MgCl 2 plus N/20 CaCl 2 , 75 hours; No. 18, N/10 MgCl 2 plus 

 N/100 CaCl 2 , 75 hours; No. 19, control — distilled water, renewed after 

 75 hours; No. 20, control — distilled water, not renewed. The plants 

 were 21 days old when treated. The first reading was taken after the 

 roots had been in the distilled water exactly 30 minutes (in No. 20, 

 75 hours). Nos. 19 and 20 were placed in distilled water at the same 

 time that the cultures to be treated were placed in their respective 

 solutions. 



