1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 793 
baskets having wooden bottoms and tops were used, the tops 
containing holes large enough for the free insertion of the cen- 
trifuge tubes, and the bottoms, slight depressions into which 
the tubes might rest. It is always necessary to run blanks 
with Fehling’s solution since some reduction always takes 
place. The cuprous oxide solvent must be free from ferrous 
iron, and this can be assured by the addition of a trace of per- 
manganate. 
Method of setting up expervments.—Fifty ec. of the sub- 
strate to be used were placed in 125 cc. Erlenmeyer flasks with 
2 per cent toluene as an antiseptic. If the series were main- 
tained longer than six weeks, another 2 per cent toluene was 
added. As previously noted, in these carbohydrate experi- 
ments the material used for enzyme action was an alcohol 
precipitate from a water extract of algal powder or pulp. 
This was diffused in water so that 10 cc. of the diffusion 
represented 2 grams of the original tissue. Usually this 
amount was added to the substrate to be tested. Duplicates 
and checks were set up in accordance with the following model 
series for starch: 
1. 50 ce. starch, 10 cc. enzyme diffusion. 
2. 90 ee. starch, 10 cc. enzyme diffusion. 
3. 50 ce. starch, 10 cc. boiled enzyme diffusion. 
4. 50 ce. starch, 10 cc. boiled enzyme diffusion. 
5. 90 ee. starch, 10 ce. distilled water. 
6. 950 ce. starch, 10 ce. distilled water. 
°To make this table more generally available, it is printed here in full. 
Shaffer’s table of copper-glucose equivalents 
mgms. mgms. mgms. mgms. mgms. mgms. 
copper glucose copper glucose copper glucose 
OFT 47 6.0 2.74 20.0 9.71 
1.0 .62 7.0 Bie7Al 25-0 119) 245) 
Nats) .88 8.0 3.68 30.0 14.80 
2.0 i odlit 9.0 4.15 35.0 17.40 
Zao iL By? 10.0 4.65 40.0 20.00 
3.0 1.50 12.0 5.61 50.0 25.00 
Ba 1.67 14.0 6.61 60.0 30.10 
4.0 1.82 16.0 7.61 80.0 40.40 
5.0 Dei 18.0 8.65 100.0 50.70 
