. "For example, gelatin derivatives,graft polymers of gelatin with other polymers, albumin, proteins such as casein, cellulose derivatives such as hydroxyethyl celluloses, carboxymethylcelluloses, and cellulose sulfates, sodium alginate, saccharide derivatives such as starch derivatives,and various synthetic hydrophilic polymers including homopolymers and copolymers such as polyvinyl alcohols, polyvi" . . .