5) 
110° C. to determine the dry matter, which was found to be 1.851 
grams; another portion, suspended in 25 cc. of water, after the addi- 
tion of 10 ec. of hydrogen peroxid developed 82 cc. of oxygen in 
thirty minutes; the third part was left with 100 cc. of a 10 per cent 
glucose solution for twenty-four hours and, after filtering the ferment- 
ing liquid, the filtrate and residue were tested separately. The filtrate 
gave no reaction with hydrogen peroxid; the residue treated as above 
gave 108 ec. of oxygen in thirty minutes. This sample of yeast con- 
tained no oxidase and but a trace of peroxidase. 
Another test was made with fresh beer yeast, the yeast being free 
from any trace of oxidase and containing only a faint trace of peroxi- 
dase. A portion of the yeast was suspended in 100 cc. of water and 
with frequent shakings the mixture was divided into two equal parts, 
one part serving for the determination of the dry matter, which was 
found to be 0.540 gram. The other part was left with 3 cc. of chlo- 
roform for twenty-four hours in order that the cells might be killed 
and consequently give up their enzyms to the water more easily, thus 
making it possible to determine whether there was any soluble catalase 
present. This was found to be the case. The clear filtrate gave, upon 
the gradual addition of 15 ce. of hydrogen peroxid, 117 cc. of oxy- 
gen in thirty minutes. The killed yeast itself, however, after washing 
gave 452 cc. of oxygen in fifteen minutes. This hardly leaves any 
doubt but that the amount of a@-catalase here is larger than the amount 
of f-catalase. It is noticeable also that the fresh beer yeast is richer | 
in total catalase than bakers’ yeast. 
Various bacteria also produce considerable catalase, | Bacillus pyocya- 
neus, for example; but the amount depends to some extent upon the 
conditions of nutrition. In a nutrient fluid containing 0.5 per cent 
peptone and 1 per cent glycerol or cane sugar as organic materials 
there was much less catalase produced than in a solution containing 1 
per cent glycerol, 0.2 per cent tyrosine, and 0.2 per cent sodium 
acetate, but no peptone. 
In the animal kingdom catalase is also of general occurrence. The 
aqueous extracts of spleen, pancreas, liver, kidney, brain, muscles, 
and also the blood serum show the power of catalyzing hydrogen 
peroxid, but certain secretions, as, for example, the urine, lack it. 
Infusoria, insects, worms, and mollusks were examined also with 
positive results. | 
The luminous parts of a lightning beetle do not contain a markedly 
larger proportion of catalase than other parts of this insect. Dif- 
ferent parts of about equal size were crushed with about 10 ce. 
‘Other oxidizing enzyms—oxidase and peroxidase—do not appear to be produced 
by many bacteria. Cultures of B. subtilis and B. pyocyaneus did not show them, but 
according to Roux (Comptes Rend., vol. 128, p. 212, 1899), B. coli can produce one 
of these. 
