THE EXCHANGE OF IONS 
271 
/O // /S /f /s 
showed a marked loss of electrolytes, this loss decreasing somewhat in 
magnitude as the concentration of the solution increased. After this 
preliminary period of steady loss, the roots seemed to gain the ability 
to resist the action of the solutions \ 
and during the remaining ten days 
maintained themselves without af- 
fecting in a decided way the electro- 
lytic concentration of the media. 
The loss of ions which took place 
during the first four or five days 
remained as the net result of the 
ionic exchange between the solu- 
tions and the roots. 
In the solutions of higher con- 
centration, a similar period of pre- 
liminary loss was seen, diminished, 
however, in comparison with that 
seen in the more dilute members of 
the series. The following recovery 
was, however, more complete and 
the roots were often able to absorb 
sufficiently to bring the solution 
back to approximately the original 
concentration. In some cases the 
absorption phase developed suffi- 
ciently to show a net absorption by 
the roots prior to the setting in of 
the final leakage. Such a result 
was seen in the cultures growing in 
solutions of the original concen- 
trations 224, 228, 320, and 3527lf 
X io~^ Such a net gain, how- 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
7 
/ 
ever, never quantitatively equalled 
that seen in Ca(N03)2. The roots 
of Lupinus with difficulty main- 
tained a net absorption in KNO3 
solutions. 
This result was reflected, to a great degree, in the growth of the 
roots placed in these solutions. Poor growth was the rule in the 
/O // /3 ^ /S 
Fig. 7. Curves showing the changes 
in concentration of the KNO3 solutions 
used in experiment 7. 
