18 
oxidizing influence upon the enzym. This accounts for the rapia 
decrease of the amount of oxygen developed and for the fact that a 
point is reached comparatively soon where the enzym becomes entirely 
inactive. Sweated tobacco, 0.1 gram of which developed 32 cc. of 
oxygen in fifteen minutes when suspended in a mixture of 10 ce. 
water with 5 cc. hydrogen peroxid, did not develop any more after 
the same quantity had been left for fifteen hours in contact with 25 ce. 
of the same mixture. It may safely be assumed that the detrimental 
effect of hydrogen peroxid is diminished very much by high dilution. 
The activity of /-catalase increases up to a temperature of about 
40° C. With further elevation of the temperature the oxidizing action 
of hydrogen peroxid upon the enzym becomes more powerful than 
the catalytic action of the enzym upon the hydrogen peroxid, and the 
enzym very soon loses its activity. A solution was prepared of 0.2 
per cent crude /-catalase obtained from sweated tobacco in the manner 
above described. Thirty cc. of this solution were heated to deter- 
mined temperatures, and after addition of 5 cc. of hydrogen peroxid 
of 20° C. the time required for the development of a certain volume 
of oxygen was noted. At 50° and 60° C. the action was energetic for 
one minute only, after which it slowed down rapidly and stopped. 
Effect of heat on action of B-catalase. 
Tempera- Vices oa ome vay Seta 
ture. | of test. _| oxygen, nee 
| 
IC Minutes. ce. 
2) pee 52. 40 | 
AO ee as? Br | 40 | 
HOM Eas be 4 29 | Action stopped after 4 minutes. 
GO ses... 2 
| 23 | Action stopped after 2 minutes. 
GENERAL BEHAVIOR OF a- AND /-CATALASE. 
Both the soluble and the insoluble catalase resist the effects of time 
longer than the ordinary oxidases, as has already been mentioned. 
The writer examined leaves of various species of Solanum, collected 
in 1841, 1848, 1853, and 1868 (preserved as herbarium specimens), and 
observed in all of these the production of oxygen upon the addition of 
hydrogen peroxid. The leaves were first soaked in a little water before 
the hydrogen peroxid was added. ‘The leaves collected in Bes how- 
ever, showed only a weak action. a 
In an aqueous solution, free from bacteria, p- catalase loses its power 
either by self-oxidation or by changes hin the molecule by atomic 
migration, but this change is also sometimes relatively slow. Once, 
however, the writer observed this enzym in a six-months-old culture 
of Bacillus pyocyaneus, in which growth of the germ had apparently 
stopped for several months. é } 
In aqueous solution the 4-catalase is chemically changed to an inac- 
