738 
Journal of Agricultural Research 
Vol. V, No. 16 
stances which are absorbed from laboratory air by the water (Beijerinck 
and Van Delden, 1903). Be the source of this food supply what it may, 
I was interested to find if all distilled water, even the purest, had enough 
food supply or absorbed enough to support both growth and reproduction. 
Conductivity water 1 * of a value 3.03 times io“ 6 was used as in the 
preceding experiment, with, however, the following improvements in 
the method. Jena glass test tubes were used throughout. The test 
tubes were plugged with long-fiber absorbent cotton, and the prelimi¬ 
nary dry sterilization, which has a tendency to make the fibers brittle, 
was omitted. Inoculation was made with one drop of a filtered spore 
suspension which had about 25 to 50 spores to the drop. The pycnidium 
which furnished these spores was growing in aerial mycelium, so none of 
the old substratum was brought over. At all events, material brought 
with the spores was diluted nearly 200 times. After two months slight 
growth was evident as faint submerged wisps or skeins. The growth 
was less than a tenth as strong as that produced in ordinary distilled 
water. No pycnidia were formed. 
This experiment indicates that in the soluble glass and in the char¬ 
acter of the distilled water we have the important sources of the food 
supply. The motes of cotton were practically eliminated in the last 
experiment. It might be thought that the nutrition in this case was 
as good as 8ie preceding—assuming the food supply to come from 
volatile chemicals—and that the poor growth of mycelium and the 
failure to reproduce was due to the toxicity of the conductivity water. 
But the toxicity of ordinary distilled water is generally admitted to be 
greater than the toxicity of conductivity water. Moreover, this organ¬ 
ism has never shown any effects which might be attributed to toxic 
substances in the water. In the recent experiments on the toxicity of 
distilled water with other plants the nutrition phase has been neglected, 
since the conclusions have been drawn from tests with the well-nourished 
roots of seedlings. In the experiments here reported, the food supply 
carried in the plants is that which is within a few spores barely visible 
with the high power of the microscope. It is difficult therefore to 
attribute the effects to anything but the scantiness of nutrition. 
The conclusion, therefore, is drawn that while growth and reproduc¬ 
tion can take place with the meager food supply of ordinary distilled water 
in “resistance” glass, the limit of reproduction is reached with conduc¬ 
tivity water and Jena glass, but the limit of growth is still lower. 
This same relation to nutrition was shown with the following experi¬ 
ment with filter paper. It had been determined in many previous 
experiments that this organism could grow and reproduce upon filter 
paper and distilled water. Tests with tap water, distilled water, and 
conductivity water indicated that the material used for growth and 
1 1 am indebted to Dr. R. P. Hibbard, of the Michigan Agricultural College, for the conductivity water. 
The measurements of resistance were also made by him. 
