THE HARMFUL ACTION OF DISTILLED WATER 
267 
glass container. The Potomac water check showed more irregularity 
in its behavior due to causes not determined, the result being a gradual 
rise in conductivity following a rather abrupt fall early in the experi- 
ment. This first abrupt fall is possibly due to the breaking down of 
CaN2(C03)2 with the formation of insoluble CaCOa. 
In order to make the general features of the experiment clearer, the 
accompanying curves have been platted. On the axis of ordinates 
one unit equals a conductivity of i X lO"* corresponding to a solution 
containing M/45,500 KCl. On the axis of abscissas five space units 
equal an interval of three days. (Fig. i .) 
It has now been shown that water of a rather high degree of purity 
is harmful to the roots of lupine seedlings suspended in it; that the 
growth rate of these roots rapidly falls off and at the end of a period of 
three days is almost zero ; that at the same time the roots continually 
give up electrolytes to the water, and the causal connection between 
the loss of electrolytes by the roots and their falling growth rate is 
regarded as almost certain. The check cultures carried on in Potomac 
water containing small amounts of the common salts present in the 
soil show a probably normal growth rate accompanied by an absorption 
of electrolytes from the river water. 
The question was next raised whether with the addition of soluble 
substances in quantities sufficient to make the water cultures osmot- 
ically equivalent to Potomac water, the growth rate of the plants would 
be favorably affected. Accordingly, cultures of cane sugar, calcium 
chloride and sodium chloride were set up having an osmotic value 
equal to that of Potomac water. 
Table IX 
Action of Isotonic Simple Solutions 
Description of medium 
Distilled water + cane sugar 
Distilled water -j- sodium chloride . 
Distilled water + calcium chloride. 
Distilled water 
Growth rate 
First 24 Second 24 
hrs., mm, hrs., mm. 
13.0 
19.0 
27.0 
12.5 
4- 5 
5- 5 
22.0 
5.0 
Electrical conduc- 
tivity at end of 
48 hrs. 
1.39 X 10-4 
20.8 X 10-4 
21.7 X 10-4 
1.22 X 10-4 
This experiment seems to show that the harmful action of distilled 
water as reflected in the growth rate is not due to the aggregate dif- 
ference in osmotic pressure between the cells of the roots and the ex- 
