1915] 



MERRILL ELECTROLYTIC DETERMINATION OF EXOSMOSIS 



543 



TABLE IV 



CRITICAL CONCENTRATIONS (THOSE JUST SUFFICIENT TO CAUSE EXOSMOSIS) 



OF SOME ORGANIC COMPOUNDS AS DETERMINED BY 



CZAPEK FOR CERTAIN PLANTS 



Agent 



Methyl alcohol 

 Ethyl alcohol 



Ethyl ether 



Chloroform 

 Chloral hydrate 

 Ethyl acetate 



Plant 



Echeveria .... 

 Echeveria and 



Saxifraga . 

 Echeveria and 



Viola 

 Echeveria. . . 



Concentration of agent 



* 



• • 



18% aqueous solution (by volume) 

 10-13% aqueous solution (by 

 volume 



Ethyl acetate 



Saxifraga hairs 

 and variegated 

 leaves of Op- 

 lismenus itnbe- 



cillus 

 Red beets 



\-\ saturated aqueous solution 

 acting for 24 hrs 



Saturated aqueous solution |. . . . 

 3 .09% aqueous solution 



3% aqueous solution acting for 



12 hrs 



Surface 

 tension * 



.71 



.65-. 70 



• • 





61- 



98 



93 



.71 



1 



2% aqueous solution acting for 

 12 hrs 



69-. 73 



* In terms of water as unity, f After 24 hours the cells had lost all tannin. 



nation for the phenomena observed, it will be seen by compar- 

 ing the results in the following experiments with the data just 

 given that the limiting values found for the exosmosis of elec- 

 trolytes do not at all correspond to the values found by Czapek 

 for the exosmosis of the tannoid substance. 



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(series 15) 

 No. 



in distilled 



15 



Conductivity curves of cultures 

 water subsequent to treatment, as follows: No. 1, ether vapor, 

 minutes, roots exposed; No. 2, 1 per cent ether in water, 15 minutes; 

 No. 15, control — roots exposed under bell jar 15 minutes. The plants 

 were 31 days old when treated. In culture 1, lice, of the initial 15cc. 

 of ether remained after the 15-minute exposure. In Nos. 1 and 2, the 

 first reading was taken exactly 30 minutes, and in No. 15, 48 minutes, 

 after the roots were placed in the distilled water. 



