310 BOTANICAL GAZETTE [OCTOBER 
reached in the peroxide solution, whatever the previous condition 
of the platinum. The following experiment shows this to be the 
case, 
One of the platinized electrodes which had previously been 
treated with active oxygen, was connected to the system: Hg— 
Hg.Cl—KCI—H.0O,— Pt, and the oxidation potential determined.” 
The hydrogen peroxide solution was of the same concentration as 
used in the previous decomposition experiments (o.1M), and con- 
tained a similar solution of phosphates to preserve neutrality. 
The rate of drop in potential is shown by the curve AB, fig. 3. The 
platinum electrode was then treated with active hydrogen and 
placed in a similar solution of hydrogen peroxide. In this case 
the initial potential was low but rapidly increased, as shown by 
CB, fig. 3, to the same equilibrium as reached in the previous case. 
By comparing these curves it will be apparent that the previous 
treatment has no effect on the potential assumed by the platinum 
after it has been a short time in the peroxide. 
Although the potential changes on the platinum indicate why 
previous oxidation or reduction should not alter the peroxidase 
activity, it makes more complicated the problem of the changes in 
catalase activity. It is apparent, however, that factors which have 
no effect on the peroxidase activity do alter the catalase action. 
In other words, the peroxidase action is quite independent of the 
rate of hydrogen peroxide decomposition, and the two reactions 
may be regarded as quite separate. Further experiments by the 
writer indicate that a similar separation of the oxidase from the 
catalase reaction may occur in the living cell. These experiments 
will be discussed in a subsequent paper. 
LABORATORY OF PLANT PHYSIOLOGY 
HARVARD UNIVERSITY 
6 Reep, G. B., Bot. GAZ. 61:523-527. figs. 2. 1916. 
