114 
a blue coloration with potassium iodide and starch, but no reaction 
with titanic acid. Nitrites were also shown to be absent. Hence, 
according to these authors, the separation of the iodine from the 
potassium iodide could only have been brought about by an acyl- 
hydroperoxide. A similar experiment carried out on a specimen 
of the Lathrsea squamaria sap which had lost its power to blue guai- 
acum gave a completely negative result. Hence the peroxide forma- 
tion with the active sap depends on the presence of the oxidase, and 
leads to the belief that the oxidase itself is of a peroxide nature, or 
that it at least contains a peroxide as one of its constituents. 
Schoenbein, in his paper on the catalytic action of organic materials 
(peroxidases and catalases) and their distribution in the plant and 
animal kingdoms ( 383 ), explains the activating and catalyzing power 
of such substances on the supposition that, like lead acetate, they 
convert hydrogen peroxide (an antozonide) into an ozonide (like 
lead peroxide), and that under the influence of the latter the former 
is actively decomposed with the production of water and molecular 
oxygen. Thus he proved that when lead acetate is added to a solution 
of hydrogen peroxide, lead peroxide (an ozonide) is formed, under 
the influence of which the hydrogen peroxide is actively decomposed ; 
and that if lead acetate be added to hydrogen peroxide solution con- 
taining guaiacum, the latter is oxidized at the same time that a part of 
the hydrogen peroxide is decomposed, for the reason that the lead 
peroxide oxidizes the guaiacum at the same time that it decomposes 
the hydrogen peroxide. According to Schoenbein, therefore, what 
we now know as the peroxidases are those substances occurring in the 
secretions and tissues of animals and plants which have the power of 
ozonizing hydrogen peroxide or converting it into an ozonide. The 
catalysis or decomposition of the hydrogen peroxide he looked upon 
as a secondary phenomenon resulting from the action of the ozonide 
thus formed upon the hydrogen peroxide remaining unchanged. 
Lepinois ( 263 ) conceives that the decomposition of hydrogen peroxide 
takes place in such a way that where only a part of the oxygen is set 
free it is fixed by the guaiacum or guaiacol. 
From their stud} r of the hydrogen peroxide-guaiacum reaction, 
Kastle and Loevenhart ( 244 ) arrived at the conclusion that the per- 
oxidases are substances which are capable of reacting with hydro- 
gen peroxide to form peroxides, which are more vigorous oxidizing 
agents than hydrogen peroxide itself. This view regarding the 
nature of these substances has been concurred in by Bach( 20 ). The 
decomposition of hydrogen peroxide and the mechanism of oxida- 
tions by means of this substance has formed the subject of a still 
further investigation by Loevenhart and Kastle ( 275 ). It is now 
known that hydrogen peroxide undergoes spontaneous decomposi- 
tion into water and molecular oxygen ; it is also known that it can 
