1905] SNOW—DEVELOPMENT OF ROOT HAIRS 31 
much as water did. Vicia sativa seemed more sensitive than corn, 
for in one set of experiments, performed at the same time as the 
above, 0.016 N solution killed the root tips and 0.008 N gave the 
best hairs. Sunflower roots. allowed to grow through the bottoms 
of pots into water and various KNO, solutions made with tap water 
grew best (in average length of roots) in 0.05 N and 0.1 N, 0.4N 
entirely stopping the growth of roots. Hairs appeared on all parts 
of the roots in 0.2 N solution, and more or less on the roots in all the 
solutions in which the roots grew (fig. 14). 
H,0 0.01 0.03 0.05 0.1 0.2 03 0.4 
Fic. 14.—Seedlings of sunflower growing in a series of KNO; solutions. 
The ill effects of .distilled water on living protoplasm has been 
shown by Lyon (46) and Lors (45, p. 67). In my experiments 
with distilled water the behavior of roots was irregular; sometimes 
they would grow well, as in one case of Vicia and another of corn; 
in other cases the primary roots would not grow into it, for example 
wheat. As a rule, however, distilled water and water redistilled 
from glass gave less hair than tap water. In one or two experiments 
with wheat the tips of the roots stopped growing when they entered 
the water, and laterals were sent out (the longest nearest the tip) 
and produced some hairs. This peculiar branching was also observed 
in several cases of corn in distilled water and sunflower roots growing 
into KNO, solution, and even more markedly in the case of wheat 
