6 J. K. Witson 
centimeter of phenoldisulphonie acid. The residue and acid was rubbed 
with a glass rod. After standing for ten minutes, 0.5 cubic centimeter of 
water was added, and then an excess of ammonia water 1:1. The develop- 
ment of a yellow color gave evidence of the presence of nitrates. This 
test was positive also with exudate water collected from maize eleven days 
old, oats nine days old, and timothy fourteen days old, growing under 
sterile conditions. 
PRESENCE OF CERTAIN ORGANIC MATERIALS IN WATER FROM HYDATHODES 
Reduction of methylene blue 
The object of the first test for the presence of organic materials was 
to determine whether or not these materials would reduce methylene 
blue. The test was made in a white porcelain crucible. To 0.5 cubic 
centimeter of a normal solution of sodium hydroxide, enough methylene 
blue solution was added so that the bottom of the crucible was just 
visible. This mixture was then heated to the boiling point and some of 
the exudate water was added. With this procedure the color of the methyl- 
ene blue entirely disappeared. On cooling, a color developed which had 
considerable red in it.. This was considered a positive test for reducing 
substances. This reaction occurs when reducing sugars, and probably 
other substances, are present in the solution, and gives a positive test 
when 0.1 cubic centimeter of the solution being tested contains 0.0000039 
milligram of glucose. This test was applied to exudate water collected 
under sterile conditions from maize, oats, and timothy, with Deere 
results. 
Sugar 
The test for sugar was made according to the recommendations of 
Heriot (1920). It was positive with amounts as small as 0.004 per cent 
of sugar. To about 5 cubic centimeters of the water from maize, four 
drops of an alcoholic alpha-naphthol solution was added, and the two 
were thoroughly mixed. Concentrated sulfuric acid was added to form 
two layers. On standing, a bright red to deep violet color appeared at 
the surface of contact of the two liquids. The color became intense ~ 
if the whole mixture was stirred and gently heated. Exudate water from 
sterile maize plants collected eleven days after planting, gave a positive 
test in less than two minutes. For exudate water collected from sterile 
oats nine days old, thirty minutes was required to produce the character- 
istic reaction. The test for sugar was positive with exudate water collected 
from sterile timothy plants varying in age from nine to eighteen days. 
Enzymes 
Catalase-— To about 9 cubic centimeters of the exudate water from 
maize, 0.5 cubic centimeter of hydrogen peroxide was added, and the 
solution was gently rotated to insure a thorough mixing. After a few 
minutes, bubbles began rising from the interior of the mixture. This 
action was accelerated when the mixture was warmed. No bubbles 
appeared in a similar mixture when distilled water and hydrogen peroxide 
were used. A similar determination with boiled exudate water gave 
