[Vol. 2 



484 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



tion of electrolyt 

 of the medium — i 



s8 — as seen by the decrease in conductivity 

 a those cultures in which the distilled water 

 was not renewed. The reabsorption of electrolytes has been 

 observed to be a phenomenon characteristic of normal, healthy 



TABLE VIII (Series 6) 



COMPARATIVE EXOSMOSIS IN RENEWED AND UNRENEWED DISTILLED WATER 



Culture 



no. 



1 

 2 

 3 

 4 

 5 



6 



Water 

 renewal 



Conductivity Readings 



Fre- 

 quency 



Every 



day 

 None 



Every 



2 days 

 None 



Every 



4 days 

 None 



Every 



day 

 Every 



day 

 Every 



2 days 

 Every 



2 days 

 Every 



4 days 

 Every 



4 days 



1st 



2nd 



3rd 



4th 



5th 



32.9 10.4 

 36.3 22.8 



10.8 



9.3 



25.0 14.3 

 12.9 15.0 

 10.7 12.4 



10.0 



21.4 



9.6 



13.6 

 16.1 



8.9 

 17.8 

 10.7 

 11.0 

 16.1 



15.9 19.5 



9.7 

 15.2 



6th 



7th 



9.4 

 12.5 



Dura- 

 tion 

 of 



treat- 

 ment 

 days 





Total 

 increase 



in 

 conduc- 

 tivity 



10.2 

 11.4 



7 

 7 

 8 

 8 

 16 

 16 



49.5 

 5.4 



16.4 

 5.0 



36.1 



13.5 



peas, when transferred from a full nutrient solution to dis- 

 tilled water, after being in the latter medium one or two 

 days. 



i 



In order to obtain some additional information regarding 

 the relations between the conductivity of the medium and the 

 plants grown therein, series 7 containing 50 cultures was set 

 up in full nutrient solution, ten Canada field pea plants to 

 each culture. The nutrient solution was not renewed. At the 

 end of each five-day period 5 of the cultures were taken down, 

 the green weight of tops of the plants in each determined, 

 and the conductivity of the solution measured ; and from these 



results the average 



weight of tops and the average 



conductivity of each set of 5 cultures were obtained 

 was done throughout the entire period of 50 days. 



This 



The 



obtained are given in table ix and plotted 



fig. 1. In the latter the abscissa 



day 



and the 



ordinate both specific conductivity and green weight of top 

 The values given for conductivity should be multiplied by 10" 



5 



