/ 
) 
139 
like manner Battelli and Stern ( 37 ) claim to have shown that cata- 
lase inhibits to some extent the oxidations produced by ferrous sul- 
fate in the presence of animal tissues. Hence they, too, are of the 
opinion that the function of catalase may be to prevent the excessive 
oxidation of organic substances in the living cell. According to 
Jolles and Oppenheim ( 227 > 229 ) the catalases of the blood eliminate 
oxygen from oxyhemoglobin, and this oxygen is then transferred to 
the tissues by the oxidases. 
On the other hand the fact that catalase can not decompose either 
the substituted organic peroxides, such as ethyl hydroperoxide, or 
the oxygenases (Bach and Chodat, 29 ), both of which are probably 
more powerful oxidizing agents than hydrogen peroxide, is difficult 
to reconcile with the view that the function of catalase is to protect 
the organism against excessive oxidation. As pointed out by 
Chodat ( 116 ), the only property of the catalases of which we have any 
certain knowledge at present is their power to decompose hydrogen 
peroxide into water and molecular oxygen. In this respect they 
differ from all other known catalj'sts. Thus all other catalysts of 
this kind can not only decompose hydrogen peroxide but they also 
have the power of rendering active the oxygen thereof. Thus finely 
divided platinum actively decomposes hydrogen peroxide. It also 
gives the guaiacum reaction both with hydrogen peroxide and with „ 
molecular oxygen. As shown by Kastle and Clarke ( 242 ) potassium 
iodide actively decomposes hydrogen peroxide at 100° C.; it was also 
found to greatly accelerate the oxidation of formic acid by hydrogen 
peroxide at 60° C., whereas potassium chloride neither actively de- 
composes hydrogen peroxide nor does it increase its oxidizing powers. 
If, therefore, the catalases are really exceptional in this regard, they 
certainly afford a very remarkable class of exceptions, and of such a 
nature, indeed, as to be altogether inexplicable at the present time. 
On the other hand the thought naturally suggests itself that they are 
not exceptional at all, but that they simply represent special cases 
under the general rule governing the conduct of such substances 
toward hydrogen peroxide. Thus it is readily conceivable that the 
catalases, like the peroxidases, combine with hydrogen peroxide to 
form an unstable holoxide derivative, thus: 
/i + H 2 0 2 = H 2 Z0 2 . 
This might prove to be so unstable, however, that it would decompose 
in the sense of the equation — 
H 2 A0 2 = a+h 2 o + o, 
before it would have' a chance to effect the oxidation of any oxidiz- 
able substance at hand; or in the event that oxidations occurred, it 
