Evagination of the cysticercoid inPolycercus lumbrici

Abstract

A number of experiments was carried out onPolycercus lumbricito induce evagination of the cysticercoidin vitro. The results indicate that in nature the containing cyst is ruptured by pressure and abrasion in the gizzard of the bird host and that evagination is induced mainly by the action of gastric juice followed by pancreatic juice, heat assisting the process by exciting vigorous movements in the larvae. By a process of elimination it has been shown that the effective agents are the pepsin in the gastric juice and pancreatin in the pancreatic juice. The latter probably causes contraction of the muscles of the wall of the caudal vesicle which forces out the scolex.