LIBERATION OF ORGANIC MatTrEerR BY Roots oF GRowinG PLANTS’ 17 
before maturity. By painting the blades with a ferric chloride solution, 
it was found that this chlorosis was due to a deficiency of available iron. 
Therefore about 0.5 gram of ferric phosphate was added to nga container 
before sterilization. 
SETTING OF THE PLANTS 
Before the plantlets were set into the mouth of the flasks they were 
thoroly examined for contamination. Only the very best plantlets were 
used, and if properly handled they suffered no setback. In case the 
plantlets were large enough when placed in the flasks, they were wrapped 
in sterile cotton and the beaker was removed. In other cases several 
days were required for the plants to become large enough, and in this 
event the beaker was left on. 
HARVESTING THE PLANTS 
The plants were harvested in all stages of growth, as is shown by 
figures 5 to 9. The harvesting process consisted in bringing flask and 
plant to the laboratory, and, in most cases, first making a photograph 
and subsequently opening the flask by removing the plant and the cotton 
packing. When this was done the solution was examined for infection, 
which was determined by plating about 10, 5, 1/10, and 1/100 cubic centi- 
meters. The medium used in the plates contained, in addition to peptone 
and beef extract, some form of sugar, usually glucose. The plates were 
incubated at from 20° to 25° C. for a week, or longer in case no infection 
was noted. The results reported in the subsequent data herein were 
obtained from the platings in which no infection was found, and these 
flasks were considered to be sterile. 
ANALYSIS OF NUTRIENT SOLUTIONS AND RESIDUES IN BOTTOM OF FLASKS 
The presence of nitrite nitrogen was determined by Ilosvay’s modifica- 
tion of Griess’ test, described by Treadwell (1915). 
A qualitative test for the presence of nitrate nitrogen was made by the 
diphenylamine method (Withers and Ray, 1911). When it was present, 
ie total quantity was determined by the phenoldisulfonic-acid method, 
‘slightly modified by the addition of 5 drops of a 0.5-per-cent solution of 
‘Na:CO; before evaporating to avoid any loss of nitrogen which might be 
