1915] 



DAVIS — ENZYME ACTION IN MARINE ALGAE 781 



Chemical composition. — Greenish ('81) found agar from 

 Fucus amylaceus to consist of 37.21 per cent gelose (probably 

 galactan since it passed to galactose on hydrolysis) and that 

 from Sphaerococcus crispus of 60 per cent of the same carbo- 

 hydrate. Konig and Bettels ('05) give the carbohydrate com- 

 position of agar-agar from Gelidium as 33 per cent galactans 

 and 3.1 per cent pentosans; by hydrolysis, d-galactose and 

 levulinic acid were split off. Giinther and Tollens ('90) 

 found fucosan in Fucus from which the methyl-pentose, fucose, 

 was split off. Galactose was also demonstrated. Sebor ( '00) 

 obtained galactose, glucose, and fructose from the slime of 

 Chondrus crispus by acid hydrolysis. He held that the slime 

 is a very complex carbohydrate of high molecular weight, 

 made up chiefly of galactosan, glucosan, and fructosan. 



The cleavage products of Porphyra laciniata, as investi- 

 gated by Oshima and Tollens ('01), were found to consist 

 chiefly of 1-galactose and mannose, but glucose, fucose, and 

 other pentoses were also obtained. Miither and Tollens ( '04) 

 found methyl-pentosans in several of the Fucaceae. Konig 

 and Bettels ('05), working on the carbohydrate hydrolytic 

 products of various species of Porphyra, Gelidium, Laminaria, 

 Cystophyllum, and Enteromorpha, found them to consist of 

 such hexoses as galactose, dextrose, and fructose, as well as 

 several pentoses, chiefly methyl-pentoses. Enteromorpha 

 yielded a pentose — rhamnose. The results of Swartz ('11) 

 agree with those above, namely, that for all forms studied, 

 representatives of the "greens," "browns," and "reds," 

 pentosans were always present, and galactans frequently so. 

 Kylin ( '13 ) , by direct extraction with warm water of crushed 

 Ceramium, Furcellaria, and Dumotia, obtained substances 

 that gave the mucic acid test for galactose, as well as 

 the phloroglucin test for pentosans. Substances giving pen- 

 tosan reactions alone were isolated from the slime of Asco- 

 phyllum nodosum, Fucus vesiculosus, and Laminaria sp. He 

 was apparently unable to substantiate the finding of galactan 

 in Fucus by Giinther and Tollens, and this negative result also 

 conflicts with the statement of Swartz, who says that the 

 gelatinization in the algae is due to the galactan groups. 



