624 EMERSON: BLACKENING OF BAPTISIA TINCTORIA 
experiments, the colors given above being considered the normal 
reaction and any variations, as the rapidity in the change, or shades 
of blue, were taken to mark disturbance in the action of the enzyme. 
It was found that the guaiac solution did not keep its power more 
than three or four days. The best reactions were produced the 
day it was made up. Green * considers that it is not safe to rely 
upon the guaiac test as a method of recognition for an oxidase, as 
several ordinary chemicals and mineral compounds also yield a 
blue color with it, and says the surer way is to isolate the enzyme 
and prove its presence by its action. On the other hand Loew f 
considers that ‘such objections are groundless when fresh organized 
tissues are underinvestigation. Other oxidizing influences are easily 
recognized by control tests, which the careful worker will not omit 
to make. . . . Such blue reactions are not restricted to certain 
limits of temperature as the reactions of oxidizing enzymes are.” 
Temperature experiments. — These were made by putting five 
or ten cubic centimeters of the enzyme solution into tubes and 
exposing them for five, ten, fifteen and thirty minutes as nearly as 
possible to the same temperature, by means of water baths. Ex- 
posures begun at 55° C. and up to 75° C. showed no difference 
from the normal. At 75° C. for shorter exposures the guaiac or 
oxidase reaction was slower in appearing and not such a good 
blue, and the hydrogen peroxide or peroxidase coloring became 
greener and clear, instead of deep blue. For longer exposures the 
reactions were still slower. 
At 79° C. to 81° C. for thirty minutes the guaiac reaction was 
very slight; the peroxide light blue, and the color faded. 
At 85° C. for five or ten minutes there was almost no reaction 
to gum guaiac, and the peroxide reaction was green and clear and 
slow ; while at 86° to 87° C. for twenty and thirty minutes there 
was no reaction to either. Therefore the thermal destruction 
point is 86° C. for long exposures and 87° C. for shorter times, 
that of the oxidase being probably a few degrees lower than that 
. for the peroxidase ; the third extractions were a trifle more sensi- 
tive than the original one. 
* Green, J. R. The soluble ferments and fermentation. 1899. 
t Loew, O. Physiological studies of Connecticut leaf tobacco, 31. (U. *- 
Dept. Agriculture Rep. No. 65.) 1goo. 
