accharide--O--CH2 CH(OH)CH2 NH--A--COOH, Polysaccharide--O--CH2 CH(OH)CH2 --B--CH2 CH(OH)CH2 NH--A--COOH and ##STR11## wherein A is alkylene having one to 16 carbon atoms which is optionally interrupted by a group selected from the class consisting of --O-- and --NH--, B is a group of the formula: --(CH2)n -- or --O(CH2)n O--, and n is an integer of 1 to 6, in an aqueous solvent to give a water-in