1915] 



MERRILL DISTILLED WATER 



485 



in order to get the specific conductivity values. In the case 



of the weights the numbers in the margin represent ten times 



the actual weight in grams, e.g., 40 in the margin = 4.0 grams. 



From the results it is seen that both the increase in green 



TABLE IX (Series 7) 



GROWTH 



OF PLANTS AND CONDUCTIVITY OF FULL 



NUTRIENT MEDIUM FOR 







50 DAYS 







Cultures 

 nos. 



Length of period 

 in full nutrient 



Av. green wt. 

 of tops in 



each culture 



Specific conductivity ' 



of period 



* at end 



A * %• WJ# 



days 



grams 



Minimum 



Average 



Maximum 



1- 5 



5 



3.81 



93.22 



96.25 



98.19 



6-10 



10 



8.12 



57.47 



61.03 



66.93 



11-15 



15 



9.47 



32.38 



34.83 



37.59 



16-20 



20 



8.66 



24.38 



32.68 



46.05 



21-25 



25 



8.69 



15.73 



18.19 



21.69 



26-30 



30 



8.00 



13.74 



20.63 



30.28 



31-35 



35 



7.10 



10.02 



15.98 



21.23 



36-40 



40 



6.77 



11.16 



14.23 



16.19 



41-45 



46 



6.09 



6.88 



11.44 



22.51 



46-50 



50 



5.01 



13.00 



16.97 



28.11 



* The numbers in the three columns are to be multiplied by 10~ 6 in order to 

 arrive at the specific conductivity values. 



weight of tops and decrease in conductivity of the medium are 

 most rapid and pronounced during the first 15 days. After 

 that period both the green weight and the conductivity gradu- 

 ally decline, but the latter more slowly than the former. 



curves of the minimum, average, and maximum 



While the curves 

 conductivity remain very close together during the first 15 

 days, they become more divergent after that time. The green- 

 weight curve shows a gradual decline as the age of the plant 

 increases, after a certain period, due to the drying of the 

 tops and consequent loss of water. Different curves would, 

 of course, have been obtained had the nutrient solution been 

 renewed. 



In table x and fig. 2 are seen the results of series 8, a 

 similar experiment with distilled water, the same units being 

 used as in the previous case. The green weight of tops in- 

 creased during the first 10 days and then gradually declined 

 to the end of the experiment. The conductivity of the water 

 was practically the same on the 10th as it had been on the 

 5th day. Evidence from other experiments, however, indicates 



