[Vol. 2 



554 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



No. 7 were brownish only in spots, but were of about the same 

 flaccidity as those of No. 6. 



Having found that a treatment of 17 hours under the con- 

 ditions indicated above was not sufficient to yield the most 



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10 

 Days 



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16 



18 



20 



Fig. 



1G. Conductivity curves of cultures (series 10) in distilled 

 water subsequent to treatment, as follows: No. 0, N/20 MgCl2, 17 

 hours; No. 7, N/20 CaClo, 17 hours; No. 8, N/20 MgCl 2 plus N/20 

 CaCl 2 , 17 hours; No. 9, "control — distilled water, renewed after 17 

 hours; No. 10, control — distilled water, not renewed. The cultures 

 were 17 days old at the time of treatment. The first readings Mere 

 taken in all cases after the roots had been in the distilled water 

 exactly 30 minutes. No. 10 remained in the full nutrient solution until 

 the treated cultures were transferred (after the 17-hour period) from 

 the respective solutions to distilled water. 



positive results, it was decided to try stronger concent 

 and longer periods. Figure 17 shows the conductivity 



after a period of treatment 

 interesting results were obtained 



extending 



/5 



hours. S 



N/10 MgCl 2 gave the high 

 est readings, closely followed by N/10 MgCl 2 plus N/10 CaCl 2 

 the N/20 MgCl 2 plus N/20 CaCl 2 curve is very similar to tha 



