EMERSON: BLACKENING OF BaPTiISIA TINCTORIA 627 
enzyme solutions which was noticeable even in the weaker ones, 
making the color reactions greenish instead of blue. There was 
no precipitate in any and the color faded in most of them. In 
these results it is seen that it is the oxidase which is more resis- 
tant, while in the thermal tests it was the peroxidase. Loew * 
states that in the majority of cases the oxidase will prove the 
more energetic of the two but it succumbs much more quickly to 
noxious influences, as alcohol or heat. 
A few experiments were tried with both citric acid and sodium 
hydroxide, using for each .5 cc. of $ normal solution (where a 
slight though decided reaction to both guaiac and hydrogen per- 
oxide was observed), and then heating the tubes. It was found 
that the thermal destruction point was thus reduced from 86° to 
79° C, 
MISCELLANEOUS EXPERIMENTS 
1. The experiments given above seemed to prove that there 
were two oxidases and it was thought probable that catalase was 
also present, but although two attempts were made to prove this 
neither was successful. Hydrogen peroxide was poured on 
freshly chopped leaves and though bubbles came off, when col- 
lected they proved to be only air, not oxygen. However, when 
hydrogen peroxide was dropped on freshly made hand-sections of 
the stem many air-bubbles came off, especially from the wood and 
xylem, which action may have been due in part to catalase, as 
this property of developing oxygen by decomposition of hydrogen 
peroxide is one which Loew } proved to belong to catalase. 
2. Tubes with enzyme solution were exposed to sunlight and 
strong light for several hours, together with controls wrapped in 
black paper, so that all were at the same temperature, but all gave 
perfectly normal reactions. 
3. A solution of hydroquinone was made up (one gram in 
100 cubic centimeters of distilled water), and equal amounts of 
this and the enzyme solutions, and one tube of distilled water and 
hydroquinone were put aside in the dark, for twenty four hours. 
As no result was apparent for this period they were left for a 
spt oew, O. | Curing and fermentation of cigar leaf tobacco, 30. 1899. 
t Loew, O. Physiological studies of Connecticut leaf tobacco, 23. 1900 — 
Loew, O. Catalase. gol. 
