As is well known, however, manganous oxide is spontaneously oxi- 
dizable, and in the course of this oxidation molecular oxygen is split 
into two atoms, one of which combines with the manganous oxide 
to form the peroxide, the other going to oxidize the liydroquinon or 
other oxidizable substance, which ordinary molecular oxygen is 
powerless to oxidize. Thus 
MnO + 0 3 = Mn0 2 + O, 
and 
C 6 H 4 (0H) 2 + 0=C 6 H 4 0 3 + H 2 0. 
In the presence of an acid, R" H 2 , and a substance like liydroquinon 
the latter is oxidized. Thus a further amount of liydroquinon is 
oxidized and the manganese salt regenerated, thus: 
and 
R" H 2 + Mn0 2 = R" Mn + H 2 0 + O, 
C 6 H 4 (0H) 2 + 0 =C 6 H 4 0 2 + H 2 0. 
In harmony with this view Bertrand proved that while manganese 
peroxide is stable in dilute acids it is reduced on adding liydroquinon, 
with the production of quinon and a manganous salt. He was there- 
fore led to consider the oxidases whose oxidizing powers are so greatly 
intensified by a manganese salt as special combinations of man- 
ganese and an acid radicle, the latter probably of a proteid nature 
and partaking of the nature of a ferment and having just the affinity 
necessaiy to maintain the metal in solution. According to this con- 
ception the manganese would be the really active element of the oxi- 
dase, so far as the activation and transfer of oxygen is concerned, 
whereas the acid albuminoid radicle would impart to the ferment its 
other properties, such as its conduct toward heat, solubility, etc. 
According to Rey-Pailhade ( 343 ) the reducing ferment which he has 
described under the name of “philothion” possesses the properties of 
the acid albuminoid radicle of the oxidases. 
Other observers have found manganese in oxidases. Thus Lepi- 
nois ( 264 ) found both manganese and iron in the oxidase of the roots 
and leaves of aconite and belladonna. Carles ( 110 ) found manganese 
in quantity in the oxidase of valerian root. According to Vitali ( 440 ) 
the oxidase of pus contains a trace of manganese, and to this it owes 
its oxidizing properties. Aso ( 15 ) likewise found both manganese 
and iron in the ash of the oxidase of tea leaves. Portier ( 332 ) has 
also shown that the activity of the oxidase of the branchies of 
Artemis exoleta is generally increased by the addition of small amounts 
of sulfate of manganese. 
According to Bacli and Chodat ( 31 ) manganese is also the active 
agent of the peroxidases. Kelley ( 249 ) has recently shown that pine- 
apple plants containing a high percentage of manganese contain a more 
