1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 817 
strate were titrated against N/50 NaOH. One per cent chloro- 
form-thymol was used as an antiseptic, and the flasks were 
kept at a temperature of 22—23°C. for 30 days. 
The forms used in table x1v show a general ability to 
hydrolyse proteins. All four proteins employed were acted 
upon by one alga or another, but peptone and casein in 
neutral and alkaline solution were the most readily attacked. 
Enteromorpha split albumin and legumin but poorly; Chon- 
drus acted upon legumin only in alkaline solution, and then 
slightly; Mesogloea failed to hydrolyse casein and legumin, 
and its action on albumin and peptone was very slow. 
The action of Ulva, Laminaria, and Agardhiella powder 
on peptone and casein in alkaline and neutral solution.—tIn- 
dications in the preceding experiment seemed to point to the 
fact that peptone and casein were more easily acted upon 
than the other proteins—and these more especially in neutral 
and alkaline solution. Accordingly, a series was set up with 
these two substrates, similar in all respects to the preceding 
one, except that the acid substrate was omitted and that Ulva, 
Laminaria, and Agardhiella were used for proteolytic action. 
Five grams of air-dried tissue were employed with 100 cc. of 
substrate. One per cent chloroform-thymol served as an anti- 
septic, and the flasks were kept at 35°C. for 30 days. Formal- 
dehyde titrations were made after 15 and 30 days and trypto- 
phane tests and amino-nitrogen determinations after 30 days. 
In the titrations 10 ce. of substrate were titrated against N/50 
NaOH, and the amino-nitrogen represents that in 2 ce. of the 
filtrate from phosphotungstic precipitated protein. 
The data in table xv tend to substantiate that of table xiv 
concerning the hydrolysis of peptone and casein. The higher 
temperature at which the flasks were maintained undoubtedly 
had something to do with the larger amounts of amino acids 
split off from these two proteins than was the case in the pre- 
ceding series, yet if we can judge by the action on carbohy- 
drates and fats, we are dealing here with the more active 
members, enzymatically, of their respective groups. 
On the whole, peptone and casein seem to be the most favor- 
able substrates of those used for proteolytic activity, and 
