23 
oxalic acids indicates merely the loss of lability by atomic migration 
without giving a decided answer as to the nature of the labil atomic 
groups themselves. 
The next question to be considered is: By what other groups in the 
molecule is the lability of those amido groups induced? The following 
tests do not give a satisfactory answer to this question, but seem to 
indicate that neither ordinary aldehyde nor ketone groups are the 
cause. The supposition as to the presence of polymerized aldehyde 
groups, however, still remains to be considered, especially the detri- 
mental action of free hydroxylamine, which might be explained by a 
dismemberment of a polymeric aldehyde group and subsequent reac- 
tion with the hydroxylamine. 
ACTION OF PRUSSIC ACID. 
One gram of tobacco containing a@- and /-catalase was mixed with 
20 ce. of dilute (2 per cent) prussic acid and the liquid was filtered 
after two hours. Ten cc. hydrogen peroxid were added to the fil- 
trate, but no trace of oxygen was obtained. In the control case, how- 
ever, 20.2 cc. of oxygen were developed in fifteen minutes. The 
residue in the filter was also tested after washing, but here the full 
original power—60 ce. of oxygen in fifteen minutes—was—observed. | 
In a second experiment the same dilute prussic acid was aliowed to act 
on the tobacco for twenty hours, and the filtrate was then tested for the 
catalytic power after the prussic acid had evaporated at the ordinary 
temperature, but no trace of oxygen was now developed after addition 
of hydrogen peroxid. The a-catalase in the residue had in this case 
also preserved the full catalytic power. It would seem, therefore, 
that while 6-catalase is easily killed by prussic acid a-catalase shows 
considerable resistance, at least as long as it is present in the undis- 
solved state. In weak alkaline solution the result differs, inasmuch as 
considerable injury is caused to @-catalase by prussie acid. 
A regeneration of the activity after evaporation of the prussic acid 
is only observed with @-catalase when the amount of prussic acid per- 
mitted to act upon it has been very small. 
BEHAVIOR OF Q-CATALASE TOWARD HYDROGEN SULPHID. 
Two grams of finely pulverized sweated tobacco were suspended in 
500 ce. of water and hydrogen sulphid passed through until com- 
plete saturation was obtained. The liquid was allowed to stand for 
twenty-four hours. The tobacco was then collected on a filter and 
after being washed well was suspended in 30 cc. of water, and 10 ce. 
of hydrogen peroxid added. In thirty minutes the volume of oxygen 
developed was 170 ec., while in the control case, after extracting the 
tobacco (2 grams) well with cold water, it was 609 cc. This shows 
