30 BOTANICAL GAZETTE [JULY 
grow through pots into water and solutions made with tap water, the | 
o.5 N solution produced the best hairs. Corn roots growing through ~ 
pots into water and solutions made with redistilled water showed ” 
hairs for the first three days; then they began to grow smooth, _ 
probably having become accustomed tothe solution (WIELER 87 © : 
p- 376), as the strongest solution was the last one in which they ~ 
became smooth. The pots were then transposed in various ways — 
to test the effect of change. A transfer from a low concentration 
to a high one does not seem to be so favorable to hair production as 
the reverse. The roots seemed to be able to bear higher concentra- _ 
tions of saccharose than of lactose or glucose (cf. LrvINGSTON 44, | 
P- 295). 
In three experiments with glucose in boiled tap water, sunflowers | 
showed very poor growth, 0.5 N being about the growth limit and 
0.1 N the limit for hairs. " 
In two experiments with glycerin in boiled tap water with sunflow- 
ers, one showed hair limit in 0.05 N and the second in 0.2 N solu- 
tion. In the latter case one jar had roots haired nearly to the tip. — 
In two experiments with mannite, sunflowers showed very poor 
growth, with o.1 N limit for growth and hairs. 4 
The only electrolytes used were the salts of Knop’s solution, and 
potassium nitrate alone. The modified ‘Knop’s solution “D,”’ used” 
by Livincston (43, p. 299), was used for two experiments with 
sunflower seeds.- The best hairs appeared in 0.2 N, where they grew : 
to the ends of the roots. The limit for growth appeared to be 0.4 N- 
and the limit for hairs 0.3. N solution. Sunflower roots passing 
through the bottoms of pots gave very good hairs in 0.1 N solution, — 
but were not healthy in 0.3N solution. The unmodified Knop’s” ; 
solution made up with redistilled water was used in various dilutions 
0.1 N being made with distilled and also with tap water, 0.2 N a 
0.3 N with tap water, while cultures in redistilled water were sl 
for control. After ten days all but o.3 N showed some hairs, the 
best appearing in o.2 N. The redistilled water gave the zone of hairs 
which appear in tap water. 
In two sets of experiments with potassium nitrate,o.o16N solution 
gave the best hairs on corn roots. The roots were inclined to be 
knobby and swollen in the stronger solutions, and the 0.008 N acted 
