1915] 



MERRILL — ELECTROLYTIC DETERMINATION OF EXOSMOSIS 



539 



25-28 inclusive are plotted in the same figure with Nos. 18 

 and 23. With plants enveloped in a steam bath the injury, as 

 expected, is very speedy and effective. Even one-half minute 

 - -\ >^n the roots are exposed — causes immediate and marked 



85 



"3 



o 





W 



2 





80 



75 



?Q 



C 65 



60 



£ 55 

 « 45 



40 



35 



25 



20 



1 



2 



3 



4 



5 



6 



7 



Days 



Fig. 0. 



Conductivity curves of cultures (series 14) in distilled 

 ^ water subsequent to treatment, as follows: No. 18, temperature of 

 * — 2.5 °C, 30 minutes, roots in tumbler; No. 23, temperature of 

 — 2.0°C, 15 minutes, roots in tumbler; No. 25, steam, one-half minute, 

 roots exposed; No. 26, steam, 2 minutes, roots in tumbler; No. 27, 

 steam, 1 minute, roots in tumbler; No. 28, steam, 10 minutes, roots 

 in tumbler. The plants were 29 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 following respective periods (the cultures whose 

 roots were in tumblers during the treatment were likewise in the dis- 

 tilled water) : No. 18, 4 hours and 49 minutes; No. 23, 4 hours and 

 41 minutes; No. 25, 4 hours and 43 minutes; No. 20, 4 hours and 

 d9 minutes; No. 27, 4 hours and 31 minutes; No. 28, 4 hours and 

 12 minutes. 



