1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 801 
compared with Ulva the difference is quite marked. As in 
the other algae, Ceramiwm showed no ability to hydrolyse the 
disaccharides used. 
A COMPARISON OF THE DIASTATIC ACTIVITY OF ULVA LACTUCA 
WITH THAT OF LEAF TISSUE FROM SOLANUM TUBEROSUM 
One of the very evident facts brought out by the data in 
the preceding tables was the relative slowness with which 
hydrolysis was carried on. This point made it seem worth 
while to compare, in a general way, the activity of such a form 
as Ulva with the starch-forming leaf tissue of a higher plant, 
one from which diastase could be isolated rather easily. The 
potato (Solanum tuberosum) was chosen. 
The Ulva tissue was from an air-dried lot that had been 
tried out earlier and had been found quite active. Fresh 
potato tops were brought into the laboratory, and both these 
and the Ulva given the ‘‘dauerhefe’’ treatment. After de- 
hydrating and drying at room temperature, both lots were 
ground in a mill, then reduced to a fine powder in a mortar. 
Exactly 18.5 grams of each were extracted with 250 cc. of 
water for 12 hours at room temperature with toluene added as 
an antiseptic, and then the protein-enzyme complex precipi- 
tated with 2.5 volumes of 95 per cent alcohol. The Ulva pre- 
cipitate was the characteristic heavy white mass to which 
attention has been called before, while that of the potato was 
finely divided and dark. 
The entire amount of each precipitate was diffused in 60 ce. 
of water. The Ulva precipitate gave a rather viscous diffu- 
sion, due to the adsorption of water by the protein particles; 
that from the potato did not all go into solution, making it 
necessary to shake the flask so that a true sample might be 
obtained. Five cc. of the ‘‘diffusion-extract’’ represented 1.84 
grams of the original dehydrated tissue, and this volume was 
used with 50 ce. of a starch and dextrin substrate. Toluene 
was added as an antiseptic, and the flasks kept at a tempera- 
ture of 31°C. for 42 days. Portions of the substrate were 
removed from time to time and sugar determinations made, 
the results of which are shown in table x. 
