UTAH ACADEMY OF SCIENCES 79 
and later continue growth when placed in full nutrient 
solution, but their growth would not then be entirely 
normal. . 
An interesting effect in this connection is the delayed 
maturity and prolonged growing season of plants first 
grown in distilled water and later grown in full nutrient 
solution as compared with those in the nutrient medium 
the entire time. 
If distilled water is in itself toxic then it should be 
interesting to get quantitative data on its effects as mea- 
sured by the power of plants so treated to recover. 
This power should furnish a good index regarding the 
extent of any injury suffered. By comparing the ultimate 
time limits for various media of slight toxicity after which 
recovery in full nutrient solution is possible, we are able 
to get a basis on which to determine the relative toxicity 
of each medium. Table II shows the results of experi- 
ments along this line, and gives the longest period in the 
toxic solution after which recovery is possible: 
TABLE II. 
Redistilled water 80—40 days. 
N/100 MgCl, 4— 8 days. 
N/1000 MgCl, about 20 days. 
N/1000 CaCl, & N/20 MgCl, about 16 days. 
N/12800 H,SO, about 20 days. 
N/400 KOH about 20 days. 
The solutions used have been considered as approx- 
imately the critical concentrations that would have prac- 
tically no deleterious effects on plants. That being the 
case, the results show that pure distilled water can not 
be regarded as toxic. What is here illustrated for dis- 
tilled water then is not toxicity but merely the length of 
time those plants can survive in a medium without nutri- 
ent materials. 
Suspecting that bacteria and fungi play an important 
role in the deterioration of plants kept for some time in 
distilled water, an experiment was performed to deter- 
mine the effect on the growth of the plants of sterilizing 
the medium by boiling it in a return condenser every four 
days. The results are shown in Table III. 
