396 
R. P. HIBBARD 
by distilled water has been questioned by Schulze^® who states that in 
all probability the effect produced is the result of impurities in the 
water. From our experience with lupines we would prefer to agree 
with Schulze. 
It may also be observed from a study of the experimental data 
above that the change from the last dilution to distilled water affects 
the growth rate more than changes in the other dilutions. Were the 
cause of injury due to osmotic effects, this would show up in the first 
or greater change but here we always have a better growth rate than 
in any of the other dilutions. That osmotic effects can be ruled out 
has been shown by Loeb, True and others. Can the same be said of 
low salt content? Is the low salt content of the medium the cause of 
injury? J. F. Daniels^^ showed that the destructiveness of distilled 
water cannot be due to its low content of inorganic salts. Two drops 
were diluted with equal amounts of distilled water. Into one having 
the high original salt content of the culture solution many paramecia 
were placed, into the other with a very low original salt content few 
organisms were placed. The paramecia in the first drop died quickly, 
while in the second drop they lived for days. Obviously the salt 
content was not the important factor. Here no mention is made of 
the possible deleterious effects of toxic excreta from so many organisms. 
If lupine seedlings are grown in distilled water with frequent daily 
changes the salt content will be kept quite low and in addition the 
toxic excretions will be more or less eliminated. Under these condi- 
tions lupine seedlings grow well until they show signs of injury from 
lack of nutrient salts. The experiments mentioned above, besides 
others not reported here, lead us to the belief that the problem of 
adjustment is so important that it must be taken into account in 
culture experiments. 
The Problem of Toxic Excretions 
For a little more than ten years the Bureau of Soils of the United 
States Department of Agriculture has sought to explain soil infertility, 
by the presence of deleterious substances of organic nature in the 
soils. These substances may be given off by the roots, or arise from 
1^ Frank, B. Untersuchungen iiber die Ernahrung der Pflanzen mit Stickstoff 
und iiber den Kreislauf desselben in der Landwirthschaft. Landwirthsch. Jahrb. 
17: 421-553. 1888. _^ 
1^ Schulze, E. Uber das Verhalten der Lupinenkeimlinge gegen destillirtes 
Wasser. Landwirthsch. Jahrb. 20: 236. 1891. 
