1915] 



DAVIS — ENZYME ACTION IN MARINE ALGAE 825 



shows less nuclease activity than does Ceramium, while As 

 phyllum, true to its reputation for inactivity, gives a value 

 small as to be negligible. 



b"& 



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- 

 scribed 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 cc. of fresh 3 per cent hydrogen peroxide. In 

 only two cases was direct oxidization observable — with 

 Agardhiella and Viva. 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 Viva, however, both 

 direct and indirect tests were only weakly positive. Atkins 

 ('14), 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 a ) has since 

 demonstrated indirect oxidation of the alpha naphthol-para- 

 phenylenediamine group of compounds by many of these 



