1916 Karrer; on Nereocystis 231 



Miiller^^ found glucose and xylose in Cladophora, and Rohmann^*' found 

 in Ulva a methyl pentosan which gave rhamnose. Konig and Brettels^^ 

 found the same products in Enteromorpha that Rohmann found in Ulva. 



The Rodophyceae have more or less cellulose in their walls. In some 

 there is another substance present that becomes gelatinous in boiling 

 water.^^ The gelatinous substance obtained from Chondrus crispus and 

 Gigartina mamillosa has been called carrageen. This "carrageenschleim" 

 is insoluble in copperoxyammonium and according to Tunmann gives a 

 light red color with iodine. Hydrolyzing with nitric acid gives about 

 20-28% galactose. A reddish color is also given with agar-agar, indicating 

 that they may be similar substances. 



The Phaeophyceae seem to be the most thoroughly investigated. It 

 has been shown that the cell wall of Fucus is composed of cellulose and a 

 second substance which gave a blue color with iodine in potassium iodide 

 and sulphuric acid. In 1850, Stenhouse^* treated Fucus with sulphuric 

 acid and obtained a slight precipitate which he called fucosol. Later 

 Maquenne^^ established the composition as furfurol and methyl furfurol, 

 the last being formed from methyl pentose. Tollens and Gunther^o showed 

 that the methyl pentose is an isomer of rhamnose and reduces Fehling's 

 solution. This substance, which is called fucose, gives methyl furfurol 

 when treated with hydrochloric acid. It also forms an osazone. Fucosan 

 then is that substance which upon hydrolysis yields fucose. 



Stanford-^ isolated a substance from Laminaria which he called algin. 

 Algin is separated by digesting the plant material in the cold for 24 hours 

 with a dilute solution of sodium carbonate or other alkali. The thick 

 sirupy mixture which results is filtered by suction. The filtrate is acidified 

 with hydrochloric acid and a heavy yellow precipitate is formed. Ex- 

 posure to the air turns the precipitate a dark brown, and when dried it 

 becomes a dark colored hard substance. Hoagland" found that the moist 

 precipitate gave a good reduction with Fehling's solution after being boiled 

 with 2% sulphuric acid. He concluded that algin has weakly acid prop- 

 erties and is a very complex resistant compound of the pentosan type be- 

 cause furfurol is produced upon hydrolysis. 



The cell well of Nereocystis seems to be somewhat similar to that of 

 Fucus in that it is made up of a cellulose substance, and a second sub- 

 stance which is algin in Nereocystis and fucosol in Fucus. Fucosol may 

 be similar to algin since they are both precipitated with acids and yield 



loMueller, K. Ztschr. Physiol. Chem. 45:265. 1905. 



iGRoehmann. Pestschr. f. salkowski. 1904. (Rev. in citation 11, p. 641.) 

 iTKoenig- and Brettels. Ztschr. Untersuch. Nahr. Genussmittel 10:457. 1905. 

 isstenhouse, J. Lieb. Ann. 74:278. 1850. 

 loMaquenne. Compt. rend. 109:571, 603. 1889. 



20Tonens and Guenther. Ber. Chem. Ges. 23:2585. Lieb. Ann. 271:86. 

 2iStanford, E. C. C. Chem. News 47:254-257; 47:267-269. 1883. Journ. Chem. 

 Indust. 3:297-303. 1884. v, . on ro -,o-,r 



22Hoagland, D. R. Journ. Agr. Research 4:39-58. 1915. 



