[Vol. 2 



488 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



of the 20-day period in full nutrient solution in which 12 cul- 

 tures were used) were grown under each of the specified con- 

 ditions, and the curves represent the averages for the 4 (or 

 12) cultures under each condition. To determine how much 







TABLE X 



(Series 8) 







GROWTH 



OF PLANTS ANE 



I CONDUCTIVITY 



' OF DISTILLED WATER MEDIUM FOR 







50 DAYS 







Cultures 



Length of period 



in dist. water 



days 



Av. green wt. 

 of tops 

 grams 



Specific 



conductivity* at end 

 of period 



nos. 



Minimum 



Average 



Maximum 



1- 5 



5 



2.04 



1.46 



1.54 



1.66 



6-10 



10 



3.07 



1.01 



1.34 



1.81 



11-15 



15 



2.89 



3.04 



5.43 



7.41 



16-20 



20 



2.34 



4.34 



5.92 



8.63 



21-25 



25 



1.89 



5.66 



8.15 



19.77 



26-30 



30 



1.55 



2.60 



8.26 



15.82 



31-35 



35 



1.15 



4.43 



7.80 



17.95 



36-40 



40 



.72 



17.62 



19.51 



26.04 



41-45 



45 



.68 



6.87 



13.32 



17.95 



46-50 



50 



.60 



10.51 



16.48 



29.00 



* The numbers in the three columns are to be multiplied by 10 s in order to 

 arrive at the specific conductivity values. 



increase in conductivity was contributed by the glass tumblers 

 in which the cultures were grown, 4 such containers filled only 

 with redistilled water, and containing no plants, were used and 

 the conductivity of the water determined at intervals for 20 

 days. It is seen that from the seedlings which had not been 

 in full nutrient solution at all (Nos. 5-8) the highest conduc- 

 tivity resulted, while from those which were in the full 

 nutrient solution longest before being placed in the distilled 

 water (Nos. 37-40 and 33-36), the lowest conductivity was 

 found at the end of 20 days. The other cultures at the end 

 of 20 days were midway between the two extremes. It is also 



seen that, whereas the conductivity curve for Nos. 5-8 shows 

 very little tendency to decline in the early stages, the curves 

 for the cultures which had first been in full nutrient solution 

 show that tendency to a considerable extent. And that ten- 

 dency, as we have previously remarked, is a characteristic fea- 

 ture of normal plants transferred from full nutrient solution 

 to distilled water. 



Attention should be called to the difference in the character 

 of the conductivity curves in fig. 2 and that of 5-8 in fig. 3. It 



