1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 789 
Three general antiseptics were used—toluene, alcohol to 20 
per cent, and 5 per cent thymol in chloroform. Toluene was, 
in general, the most satisfactory. Usually it was used to 2 
per cent concentration, but where large surfaces were exposed, 
as high as 4 per cent was found necessary. The chloroform- 
thymol was also very efficacious, but in the carbohydrate ex- 
periments chloroform could not be used because of its power 
of reducing copper. In the lipase work the substrate was made 
up to 20 per cent alcohol since the action seemed to proceed 
best in the presence of this antiseptic. In all cases where the 
experiments were maintained over a considerable period of 
time, it was necessary to add additional antiseptic from time 
to time. 
Checks were set up in all experiments—on the substrate, on 
the material used to demonstrate enzyme action, and on the 
substrate plus such enzyme material boiled to destroy any 
ferments that might be present. 
CARBOHYDRASES OF THE ALGAE 
In these experiments the alcohol precipitate from an 
aqueous extract of crushed, fresh or dried, algal tissue was 
employed as an enzyme source, this precipitate being diffused 
in such a volume of distilled water that one gram of the 
original material was represented by 5 cc. of the diffusion. 
Thus one can more closely compare the amounts of enzyme 
present in definite amounts of different algal tissue. The 
number of cubic centimeters of diffusion will be noted in con- 
nection with each set of experiments. 
Substrates.—Starch, dextrin, inulin, sucrose, maltose, lac- 
tose, glycogen, and in one or two cases, laminarin isolated 
from Laminaria Agardhu, were used as substrates. These 
were made up in 1 per cent concentrations with the ex- 
ceptions of maltose and glycogen, where .25 per cent, and 
laminarin, where .5 per cent concentrations were employed. 
Of the many suggested methods for making up starch paste, 
the following one used by Clark (’11) was found to give the 
best satisfaction. Ten grams of potato starch were weighed 
out and placed in a beaker with 250-300 ce. of distilled water. 
