26 
After standing twelve days another portion of the same extract had 
lost considerably more of its catalytic power, only 14.5 cc. of oxygen 
being developed in the same time. 
In another trial sweated tobacco was first exhausted with water to 
remove all 6-catalase and then left in chloroform water at the ordinary 
temperature for four weeks. It still showed a moderate reaction upon 
hydrogen peroxid, showing that some a@-catalase was still present. 
No f-catalase had here been formed from the insoluble catalase. 
The action of catalase upon hydrogen peroxid is not influenced m a 
marked degree by the presence of a little chloroform or ether.! 
BEHAVIOR TOWARD PHENOL. 
To an extract of sweated tobacco rich in /-catalase was added 0.2 
per cent phenol, but after twenty-four hours’ contact not the least ~ 
decrease of catalytic power was observed. In another case the extract 
was completely saturated with phenol, and thus contained 6.6 per cent 
of it, but here every trace of catalytic power was annihilated after 
twenty hours. 
The presence of 1 per cent phenol retards the action of the enzym. 
One-tenth gram of crude catalase was dissolved in 30 cc. water, and 
10 ce. of this solution yielded, on addition of 5 ec. hydrogen peroxid, 
25 ce. oxygen in fourteen and one-half minutes when 1 per cent phenol 
was present, while in the absence of the latter it took only eleven and 
one-half minutes to develop the same volume. 
BEHAVIOR TOWARD VARIOUS OTHER REAGENTS. 
The inquiry as to the nature of the activity of enzyms led the writer 
years ago to the assumption that in their molecules there are certain 
unstable atomic groupings (labil atomic groups). Such groups are 
on the one hand able to transform heat energy into chemical energy, 
and on the other hand are readily changed by atomic migration under 
the influence of an increased temperature or powerful compounds, 
such as acids, ete. The writer has expressed the view that the insta- 
bility as well as the activity of enzyms might be due to the simulta- 
neous presence of amido and aldehyde groups. In regard to the labil 
amido groups, their presence was rendered probable by the destruc- 
tive action which formaldehyde exerts apon the power of the enzyms. 
As to the presence of aldehyde, or also of ketone groups, no convinc- 
ing reactions could be obtained, but it remains still to be seen whether 
there are not aidehyde groups present in a less reactive polymerized 
form. The following tests with catalase were made, to characterize 
the labil groups: 
1 According to Jacoby, chloroform acts as a stimulant on’ the activity of certain 
oxidizing enzyms (Virchow’s Archiv. vol. 157), and according to Vogel (1897) 
very small doses of various ethers stimulate the cellular respiration. 
