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. Filterin 

 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 



© 



