23 
obtained from the turbid juice shows this property only to a very 
small degree while the suspended matter acts as powerfully as the 
unfiltered juice. Itis easy to prove that neither particles of the living 
protoplasm of the leaf cells nor an admixture of bacteria are the cause 
of this action, since contact with chloroform does not essentially alter 
that power after a day. Certain observations of the writer, not agree- 
ing with the prevalent views, led him to a further examination of this 
phenomenon. Several authors have observed this property with 
various organisms and ascribed it to the known enzyms contained in 
them, following Schoenbein,' who expressed this opinion in the year 
1863. 
This view was not even doubred after it was shown by Jacobson that 
this property of the common enzym preparations may be destroyed 
without injury to the true enzym nature, i. e., to the specific activity.’ 
While ptyalin, pepsin, and myrosin preparations gave Jacobson only 
small quantities of oxygen by decomposition of hydrogen peroxide, 
emulsin, pancreatin, and diastase, in freshly prepared condition, 
yielded considerable quantities. Jacobson proved that by heating to 
a certain temperature, by ‘‘exhaustion of the catalytic power” (of decom- 
posing hydrogen peroxide), by dilute acids, and ‘by various poisons, 
this property could be either destroyed or considerably weakened with- 
out the true enzym character being materially injured. 
Since it seems very doubtful that the molecule of an enzym can be 
changed to a great extent without destroying the specific property, 
the writer finds it much more natural to explain the observations of 
Jacobson by the presence of another enzym, to which this decompos- 
ing action on hydrogen peroxide is due. In the preparations of the 
common enzyms the presence of other enzyms as impurities can not be 
surprising. The further observations of. the writer have confirmed 
this view. A full account will be given later in a separate bulletin. 
Here it may suffice to sum up the main results: 
1. The property of developing oxygen by decomposition of hydrogen 
aa is due to a separate enzym. 
2. This enzym, to which the name catalase may be given, occurs in 
two modifications, one insoluble and one soluble in water. They may 
be distinguished as a and / catalase. The insoluble or a catalase is 
probably a combination of the enzym with a nucleoproteid. 
3. This enzym is killed at 72-—75° C. (161-167° I’.). It is an oxidiz- 
ing enzym, since it easily produces quinone from hydroquinone. It does 
not produce guaiac blue from a tincture of guaiac, not even in the 
presence of some hydrogen peroxide; hence it differs essentially from 
the ordinary oxidase and peroxidase. 
4, The insoluble modification is soluble in dilute alkaline liquids. 
5. In the curing process of the tobacco leaf there is a small increase 
1 Journ. Pract. Chem. vol. 89, p. 326. 
2 Jacobson, Zeitsch. Physiol. Chem. vol. 16, p. 340, 1892. 
