4 J. K. WiILson 
the exudate water from Caladiwm antiquorum gave a positive test with 
diphenylamine but no test with nitron. 
Klein examined the first drop to appear on the leaves of Boehmeria 
utilis and Fuchsia sp., and found nitrates but no nitrites. The nitrites 
appeared in the exuded water after from six to eight hours, giving a strong 
test with Griess & Lunge reagents. After two days the nitrates had 
disappeared. Klein concludes that nitrites are found in the exuded 
water only after a partial reduction from the nitrates by bacteria or 
molds. 
Lyon and Wilson (1921) grew plants whose roots were immersed in 
a sterile nutrient solution. They found in the solution surrounding the 
plant roots 5385 milligrams of organic material, consisting in part of 
peroxidase and a reducing substance which were identified by color tests. 
This organic material had been liberated by the growing plant roots. 
METHODS AND MATERIAL 
It seemed desirable in the present study, because of the scarcity of 
material and the question of feasibility, to confine the investigation 
for the most part to a qualitative determination of various organic sub- 
stances that may be present and readily detected in the exudate water. 
A number of tests were performed to determine some of the specific 
substances. Some of the tests were for the identification of specific 
organic compounds, while others were for inorganic substances. Klein 
considered that the nitrites which he found in the guttation water were 
produced from the nitrates by molds or bacteria. In order to avoid 
this complication, the various tests in this study were first performed 
on material collected from plants growing under non-sterile conditions, 
and then the technique was applied to exudate water collected from sterile 
plants. : 
The material for examination was collected from two sources. One 
was from maize grown in the greenhouse in soil. These plants were for 
the most part not more than three weeks old nor more than four inches 
high. They had from two to four blades when the water was collected. 
They were watered from an ordinary hose by spraying, but it is doubtful 
whether a great deal of this water was collected as exudate water. Exudate 
water was collected also from maize grown in water culture, and from the 
lawn grass, which was mainly blue grass, around the buildings on the 
campus. 
The second source of material was from plants grown under sterile 
conditions. Among these plants were maize, timothy, and oats, grown 
from sterile seeds sown on a sterilized substratum. 
From 20 to 30 cubic centimeters of the exudate water was collected 
in the course of an hour from maize which was growing under non-sterile 
conditions. ‘This was taken from either the ends or the sides of the blades. 
It was used immediately in testing for certain substances which it might 
contain. In all probability it was somewhat more concentrated than when 
first exuded. All determinations were made, however, on the material 
as collected. Smaller amounts were collected from maize, oats, and 
timothy grown under sterile conditions. 
