1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 829 
Ulwa in sewage-contaminated waters. In order to break down 
the proteins present in the surrounding waters and even those 
in close contact with the plant itself, it would be necessary for 
the Ulva to secrete an extracellular enzyme, since the large 
protein molecule is not diffusible into the cell. If so secreted, 
the enzyme would be quickly dissipated in the large volume 
of surrounding water. Desamidizing bacteria, on the other 
hand, have been demonstrated in harbor and shore waters 
where such algae abound. They can come into much more 
intimate contact with the protein than can the plant, and un- 
doubtedly play an important réle in rendering available at all 
times an abundant supply of organic nitrogen. 
The demonstration of nucleases acting upon the previously 
split nuclein molecule, substantiates the findings of Teodoresco 
for this enzyme. Both Ulva and Ceramium showed the 
presence of the ferment, while Ascophyllum, the only repre- 
sentative of the ‘‘browns’’ investigated, gave negative re- 
sults. Where such enzymes were formed, they compared more 
favorably with enzymes of fungi and higher plants than do 
any of the other algal ferments. 
None of the ‘‘browns’’ studied showed the presence of 
oxidative enzymes, while in the ‘‘reds’’ and the ‘‘greens’’ but 
one form gave the characteristic reactions. It is interesting 
to note that these algae, Agardhiella and Ulva, were the most 
enzymatically active forms studied. The oxidase reactions 
with guaiacum, alpha naphthol, and phenylphthalin were very 
positive, both directly, and indirectly with hydrogen peroxide. 
In all cases where enzymes were demonstrated, the action 
was very slow, being with the exception of nuclease, much less 
rapid than in the higher plants. The reason for this is not 
clear, but it cannot in all instances be due to inhibiting sub- 
stances set free upon the death of the cell. Arber (’01), as 
has been mentioned before, found that Ulva, Cladophora, and 
Enteromorpha, placed in the dark but under otherwise pre- 
sumably normal conditions, required from two weeks with 
Ulva, to two months and more in the case of Enteromorpha 
for destarching. This indicates the presence of a very slowly 
acting diastase in the cells of these algae. The metabolism 
