1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 825 
shows less nuclease activity than does Ceramium, while Asco- 
phyllum, true to its reputation for inactivity, gives a value so 
small as to be negligible. 
An interesting point is brought out by the use of nuclein— 
one that proves a check on some of the previous proteinase 
experiments. Nuclein is composed of nucleic acid bound up 
with some protein (according to Abderhalden, ’11, this is 
albumin) which must be split off by a proteinase before the 
nuclein residue is exposed to the attack of the nuclease. That 
unmistakable nuclease activity was evident, only serves to 
show again the presence of proteolytic enzymes. 
OXIDASES AND CATALASES 
Oxidases.—Direct and indirect tests for oxidase action, that 
is, for the oxidases and the so-called peroxidases, were carried 
out in all cases with fresh tissue. The general method de- 
seribed by Clark (’10) was employed, using guaiacum, alpha 
naphthol, and phenylphthalin as reagents. Five grams of the 
fresh tissue, crushed with an equal weight of fine quartz sand, 
were extracted for half an hour with 25 cc. of distilled water. 
The extracting fluid was then filtered off, the tissue residue 
pressed out, and the filtrate made up to 50 cc. Five cc.- 
portions were placed in test-tubes, and for the direct test, ten 
drops of the reagent were added; for the indirect test, this 
amount plus 1 ce. of fresh 3 per cent hydrogen peroxide. In 
only two cases was direct oxidization observable—with 
Agardhiella and Ulva. With the former, direct action was 
strong with all three reagents, and when peroxide was added 
an immediate deepening of the color occurred, showing the 
presence of peroxidases as well. With Ulva, however, both 
direct and indirect tests were only weakly positive. Atkins 
(714), it will be remembered, obtained direct tests with but 
one of twenty-nine diverse algae investigated and indirect 
tests with but seven. He thought that reducing substances 
prevent the demonstration of oxidases in other forms. As 
brought out in the review of literature, Reed (’15*) has since 
demonstrated indirect oxidation of the alpha naphthol-para- 
phenylenediamine group of compounds by many of these 
