258 
RODNEY H. TRUE 
conclusions here given are regarded as a preliminary contribution to 
the solution of the problem. 
Materials and Methods. — The distilled waters were prepared in 
Dr. Briggs's laboratory, under his supervision. As test objects, the 
radicles of Lupinus alhus, the white lupine, were chosen. This genus 
had been shown by Frank (32) to be very sensitive to distilled water 
injury, a fact rendering it an especially favorable subject for study in 
this connection. The radicles were suspended in beakers containing 
the culture solutions, glass hooks being used so to hold the seedlings 
as to suspend them with their roots in the solutions. These hooks 
were supported by a cork sheet covering the whole beaker through 
which they were thrust. The beakers used were made of glass of the 
so-called "nonsol" formula and had a capacity of 300 c.c. About 150 
c.c. of the solutions were used in each culture of four roots. These 
beakers had never been used, and were prepared by being thoroughly 
washed and steamed out. In order to get numerical data for com- 
parison, the growth rate of the roots was adopted as a criterion, and 
the standard period of time between measurements was twenty-four 
hours. A fine line of India ink was fixed at a distance of 15 mm. from 
the tip, and the change in length of this region included the entire 
growth in length of the radicle. The seeds were germinated in moist, 
chopped sphagnum carefully washed out, and the seedlings before 
setting into the culture medium were carefully 'rinsed in a duplicate 
portion of the same. 
As a check medium, tap water was chosen. This is drawn from 
the Potomac River, some miles above the city, filtered on a large scale, 
and delivered to the city through the usual appliances for distribution. 
Analyses of filtered Potomac water covering the entire period of our 
experiments are not available, but an average of the analyses made 
by Outwater (33) covering twelve months, between May, 1904, and 
August, 1905, is as follows: 
Parts per million 
Si02 5.15 
F203, A1203 4.63 
^ Ca 30.94 
Mg 4.62 
Na 3.20 
K 0.62 
CI 5.02 
SO4 8.68 
CO3 2.03 
HCO3 97.77 
