Abstract

The author reported in the previous pager on his observation of sudden death of Clonorchis sinensis cercaria before penetration into the body of fry such as Cyprinus carpio and Carassius auratus. And in these studies, the reason behind the fact was investigated and it was found that the mucous substances on the surface of a certain fishes have a strong wormicidal effect to the larva of C. sinensis. When cercariae of C. sinensis were immersed into the mucous substance of gold fish for three minutes 36 seconds to 4 minutes 20 seconds, into that of Aplocheilus latipes for 4 minutes 30 seconds to 5 minutes 20 seconds, into that of Cyprinus carpio for 5 minutes 15 seconds to 6 minutes l6 seconds, and into that of Carassius auratus for 5 minutes 20 seconds to 7 minutes 30 seconds, it was observed that they were all killed. No wormicidal effect against C. sinensis could be observed with the mucous substance obtained from Pseudorasbora parva, Misgurnus anguillicaudatus and Ophicephalus argus. No wormicidal effect against Metagonimus sp. cercaria is observed with the mucous substance obtained from Cyprinus carpio, Carassius auratus. The wormicidal effect of the mucous substances obtained from gold fish was destroyed when heated over 60 C. The movements of metacercaria of C. sinensis stopped after 10 minutes application of the mucous substance obtained from Cyprinus carpio and they were killed within 30 minutes. When the adult worms collected from the bile duct of experimentally infected rabbits for 20 to 60 days, were immersed into mucous substance from Cyprinus carpio, they were killed between 25 minutes and 35 minutes. No wormicidal effect could be observed with the mucous substance obtained from dead Cyprinus carpio, Carassius auratus, gold fish, when applied to the adult worms and larvae of C. sinensis.