274 MEASUREMENT OF THE CATALYTIC POWER OF CATALASE 
on albuminoids (Graham). The protein character of catalase is probable 
(Waentig and Steche, I.e.). The assumption of an a and a j8 catalase, 
proposed originally by O. Loew^^ would in that case be superfluous (compare 
E. Pozzi-Escot^^) and Appleman (I.e.). The activity of the catalase declines 
very slowly on filtering, especially if the solution has been previously neutral- 
ized. In the latter case the activity decreased only 8 percent. 
Unneutralized juices lose their catalytic power very soon. We found, 
for instance, in one case: 
Standing 
Reaction Time 
Strength 
2 cc. extract neutralized 
5' 
46 units 
100 
5' 
85 units 
54 
2 cc. extract unneutralized 
lo' 
151 units 
31 
I20' 
0 
There is evidence that this reaction follows also a logarithmic line. . 
Attempts to prepare the enzym in pure condition have failed. Unlike 
peroxidase, catalase adheres with a great tenacity to the alcohol precipitate. 
We have refrained in the foregoing from discussing the physiological 
questions suggested by or even suggesting our work, for such a research 
can start only after the methods are worked out satisfactorily. 
Summary 
1. A review is given of the literature concerning the question. Diffi- 
culties and inaccuracies in several methods are pointed out. 
2. According to the definition of an enzym, the reaction time is the only 
valid index of its strength. This strength can best be measured by an 
autographical method. 
3. An autographical method is given. The method shows the evidence 
of two successive reactions. 
4. The enzym is more or less injured or destroyed during the reaction. 
In most reactions the time is too short to influence markedly the logarithmic 
curve. 
5. The method given is adapted to determine the strength of a peroxide 
solution. 
6. There is evidence that the two different catalases are different 
degrees of peptisation of the same substance. 
We wish to express our grateful appreciation of the encouragement 
which Professor G. J. Peirce, by his criticism and suggestions, has given us. 
We also are indebted to Professors L. L. Burlingame and S. W. Young for 
valuable advice. 
Department of Botany, 
Leland Stanford Junior University 
24 U. S. Dept. Agric. Report 68. 1901. 
25 Amer. Chem. Journ. 29. 1903. 
