THE HARMFUL ACTION OF DISTILLED WATER 
269 
the different effects these salts have on the leaching of the cells. 
There seems to be good reason for thinking that abundant leaching of 
certain classes of compounds present in the cell would take place in 
the presence of but a single salt in the exterior medium. 
The experiment above described was repeated with a number of 
variations. 
Table X 
Action of Isotonic Simple Solutions 
Description of medium 
Growth rate 
ist 2d 
24 hrs., mm. 24 hrs., mm. 
Electrical con- 
ductivity at the end 
of 48 hrs. 
Distilled water + cane sugar 
13.0 
5-0 
i.o X 10-^ 
Distilled water + NaCl 
17.0 
9.0 
18.9 X io~4 
Distilled water + CaCl2 
24.0 
12.0 
18.9 X 10-4 
Distilled water + Ca(N03)2 
22.0 
15.0 
18.9 X 10-^ 
Distilled water + equiv. NaCl K equiv. 
Ca(N03)2 
23.0 
16.0 
18.9 X 10-^ 
15.0 
8.0 
1.25 X io"4 
Potomac water 
24.0 
22.5 
15.4 X 10-4 
Again the inefficiency of cane sugar as a means of improving 
physiological conditions is marked. The half-way benefit of NaCl 
again appears and the great help due to the presence of Ca salts is 
apparent. That it is due to the action of the Ca ion is clear from the 
fact that the benefit is derived from both Ca salts in spite of the fact 
that -different anions accompany Ca. The falling off of the growth 
rate in the Ca-containing solutions during the second day may indicate 
among other possibilities that the Ca solutions fail to supply necessary 
needs for more than a short time or that they ma}^ fail to check the 
undetected leaching of small quantities of necessary substances. 
When one half of the osmotic equivalent of Potomac water is supplied 
by NaCl and one half by CaCNOs)^, the record made by the roots is 
essentially like that produced by the Ca salt alone in full equivalent. 
This may mean that the Ca action is so marked even at this very con- 
siderable dilution (nearly equivalent electrolytically to lf/2,000 KCl 
solution) as to cover up the less favorable action of the NaCl present 
and give it in effect a Ca effect. 
The check cultures in distilled water and in Potomac water serve 
to illustrate the great difference for Lupinus alhus between the distilled 
water and Potomac water as culture media. They show clearly that 
