CARBOHYDRATES 73 



iIr' saj)()iiiii.s, arc glycosides, as aic a wide \aiiciy ol oilier pi. ml iiia- 

 lerials, iiuhiding acclals ol \arioiis simple alcohols and phenols. As 

 ail example saiicin honi willow bark, the acetal ol glucose and o-h)- 

 dioxybenzyl alcohol, may be cited. 



Among the more common carbohydrates occurring in these different 

 groups of acetals are glucose, galactose, and fructose. In some glyco- 

 sides the linkage is «; in others, /3. For purposes of classification, the 

 glycosides are sometimes divided according to the sugar involved, with 

 the names glucoside, galactoside, and fructoside indicating the nature 

 of the sugar. 



Mucilages 



The term mucilage is used to cover the colloidal materials of com- 

 plex nature from plants that are capable of forming gels or have 

 adhesive properties. Some of the materials described earlier, amylo- 

 pectin for instance, might be so classified, but in the present case the 

 word complex implies the presence of subunits other than monosac- 

 charides alone. One of the best-known mucilages, agar, is a polymer 

 of a sulfuric acid ester of galactose. Irish moss is a related member of 

 this group. All appear to be sulfuric acid esters based on polysac- 

 charides of galactose, mannose, and rhamnose, the last a methyl 

 pentose. 



REFERENCES 



Adx'ances in Carboliydrnle Chemistry. Edited by W. W. Pigman, M. L. Wolfrom, 

 et al. Academic Press, New York, annual volumes beginning in 1945. 



The Carbohydrates, Chemistry, Biochemistry, Physiology. Edited by W. Pigman. 

 Academic Press, New York, 1957. 



