1915] 



DAVIS ENZYME ACTION IN MARINE ALGAE 801 



compared with Ulva the difference is quite marked. As in 

 the other algae, Ceramium 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 cc. 

 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 cc. 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. 



