Press a small piece of freshwater fish flesh between two slides, examine for encysted metacercaria of C. sinensis under lower-lens microscope 3. Isolation of encysted metacercaria Take the 2nd intermediate host-freshwater fish and smash, digest with 250 ml digestive solution per 10 g flesh for 4 h"12 h(Digestive solution: pepsin 9.8g, I N HCI 164 mL NaCl 17 g add water to 2 000 ml). Discard rough matter by sieve filtration. After several times sedimentation of the filtrated solution, take the sediment and examine under microscop 4. Examination adult from infected animal Dissect the guinea pig(or white rat) which were infected with the aid of stomach tube approximately 30 C. sinensis cysts 40 days ago. Expose the common bile duct, gal bladder and search for the adult worms in the billiary tree.5 Press a small piece of freshwater fish flesh between two slides, examine for encysted metacercaria of C. sinensis under lower-lens microscope. 3. Isolation of encysted metacercaria Take the 2nd intermediate host-freshwater fish and smash, digest with 250 ml digestive solution per 10 g flesh for 4 h～12 h (Digestive solution: pepsin 9.8 g, 1 N HCl 164 ml, NaCl 17 g, add water to 2 000 ml). Discard rough matter by sieve filtration. After several times sedimentation of the filtrated solution, take the sediment and examine under microscope. 4. Examination adult from infected animal Dissect the guinea pig (or white rat) which were infected with the aid of stomach tube approximately 30 C. sinensis cysts 40 days ago. Expose the common bile duct, gall bladder and search for the adult worms in the billiary tree