1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 787 
second, by extracting the tissue with water and precipitating 
the protein-enzyme complex with several volumes of 95 per 
cent alcohol. Wherever possible the first method was used, 
since it was thought that in this way the maximum enzymic 
activity would be obtained. However, the fresh pulp and the 
powdered material contained a substance, or substances 
(probably tannoidal bodies), that reduced copper from Fehl- 
ing’s solution, and so in all experiments where sugar deter- 
minations were involved, it was found necessary to use the 
extraction and precipitation method; by this means all the 
unknown reducing substances were avoided. The method was 
as follows: 
To a known amount of the crushed, fresh algal material, 
3-5 volumes by weight of distilled water were added; to the 
powdered tissue, 8-10 volumes. The amounts varied owing 
to the differences in viscosity produced by the different algae. 
In some forms a relatively large amount of water was neces- 
sary in order to overcome difficulties in handling due to this 
high viscosity. Two per cent toluene was generally added as 
an antiseptic, or in some cases, 1 per cent chloroform-thymol 
mixture was used (5 per cent thymol dissolved in chloroform), 
and the extraction allowed to go for 12 hours at room tempera- 
ture, or for 4 hours at 35° C. The water extract, if at all 
viscous, was then filtered off through two thicknesses of 
cheese cloth and the algal tissue pressed out as completely 
as possible by making a tourniquet of the cloth. Filtering 
through cotton was tried at first, both with pressure and 
without, but the method had the disadvantage of slowness and 
also that of adsorption by the cotton. Neither did filter paper 
lend itself efficiently to the filtration of such viscous liquids, 
a drier residue being obtainable in a shorter time by the 
cheese cloth-tourniquet method. A press would have been 
desirable but none was at hand. If the medium were not 
viscous, it was filtered with pressure through a thin layer of 
cotton or a coarse filter paper in the bottom of a Buchner 
funnel. 
The protein-enzyme complex was precipitated with 3 
volumes of 95 per cent alcohol. After a few moments the 
