34 BOTANICAL GAZETTE [JULY 
with oxygen from the aerial parts than the other. Several experiments | 
to show the effect of diminished oxygen pressure upon the production 
of root hairs gave similar results and only one need be reported. : 
A pot of corn, the roots passing through the bottom, was sealed — 
into the top of a jar half full of a solution of pyrogallic acid. The | 
surface of the soil was also covered and sealed with paraffin, leaving 
a very small hole for watering. Any oxygen entering this hole had to _ 
pass through the moist soil before it entered the jar, where it would _ 
be absorbed by the acid. In some cultures this hole was plugged 
up with paraffin without altering the results of the experiment. Them 
oxygen pressure started at normal at the sealing and was gradually 
lowered to a possible zero. By twenty-four hours the roots were 
growing smooth, while those in the control jar showed good hairs. 
The growth was slow, consequently the lack of hair was not due to 
the rapidity of growth. Suppression of hair was the result when the 
CO, was also absorbed (by KOH), showing that the relative increase 
of that gas was not the cause of the cessation of hair production. — 
Wheat roots proved to be very sensitive to the lack of oxygen. Several 
experiments set up as above, but substituting wheat for corn, did no r 
give any result because the roots quickly turned brown and died. 
In one jar, however, several of the roots lived for a day, elongating 
in that time fromoto4™™, These living roots showed no hair for 
some distance above the tips. P| 
The experiment with corn was varied in the following manner, 
to see if the vapor of the pyrogallic acid had the effect upon the hairs. 
The pot was sealed in as before, the jar, however, being half full of 
water, boiled and cooled, covered to prevent as much as possible 
absorption of oxygen. Air was forced through two jars of pyroga 
acid, finally passing through the water to wash it of any vapor. 
apparatus was arranged as shown in fig. 15. The jar was measure 
previously and equal contents marked. The water at first was at 
and then the air was passed over slowly, displacing the water to | 
If the air coming over were entirely free from oxygen, the per cent. 
in the jar would be half the normal amount. As the rate of passage — 
would determine in great measure the completeness of the extractio 
of oxygen, an analysis of the oxygen content was not attempted, 
aim being more to do away with the acid in the jar, and to get a less 
